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I recently started using Sublime, and I think it's a great editor.
Here are some issues that I think should be addressed, mostly user interface issues:.
Can't find any way to associate certain filetypes to a certain syntax. I have to go to View->Syntax and select the correct syntax every time I open files of certain type that isn't associated to the right syntax by default.!
Zoom level on the preview scrollbar..
There are plenty of theme available, try them and maybe you'll find one that is better suited for you.
The first item in this menu (Open all with...) associate the selected syntax with the current file extension.
Reopen with Encoding and Save with Encoding could be used to convert encoding.I agree that encoding (and line ending) must be displayed in the status bar, I already asked for it long time ago.Meanwhile you can write a small plugin to display it in the status bar:Use ST2 menu to create a new plugin and replace the content with:[code]import sublime_plugin
def DisplayEncoding(view, encoding=""): view.set_status('encoding', "%s" % ((encoding if encoding else view.encoding()),))
class DisplayEncodingListener(sublime_plugin.EventListener): def on_load(self, view): DisplayEncoding(view)
def on_post_save(self, view):
DisplayEncoding(view)[/code]
Save it to your user folder.
Would it be possible to extend your plugin a bit, bizoo?
E.g.: Instead of displaying the current encoding on the left side of the status bar text, could it be placed on the right side, where the tab size and the current associated extension are? Don't know if it's possible at all... but atm it "interferes" a bit with the status line of the vintage plugin (mh, not interfering, it's more like "distracting").
It would be great, when it could display the current line ending as well (Windows / Unix).
Regards,Highend
Thanks
I've fixed the file extension assocation.
Regarding the scrollbar, I use the Dawn theme, I've tried others, but the contrast on the scrollbar doesn't change, always the same.
It is what I want too but I pretty sure it's not possible yet with the available API.The stacked text on the left of the status bar is really difficult to read
It's easy to add:
def DisplayEncoding(view, encoding=""):
view.set_status('encoding', "%s:%s" % ((encoding if encoding else view.encoding()), view.line_endings()))
but I suggest you look at this plugin:
Ty, bizoo
For (5), if you use a theme like Soda or Phoenix and set the following in your user prefs:
"highlight_modified_tabs": true,
The dot will be coloured as well which makes modified tabs much more obvious.
Regarding scrollbars, you can easily modify the theme yourself to get better visibility if you need it. Open the sublime-theme file for your theme and search for "scroll"; it looks like this in Soda:
// Standard vertical scroll bar
{
"class": "scroll_bar_control",
"layer0.texture": "Theme - Soda/Soda Dark/standard-scrollbar-vertical.png",
"layer0.opacity": 1.0,
"layer0.inner_margin": [2, 6],
"blur": false
},
You can play with the other options and can edit the scrollbar png files to increase the contrast, change colour etc.
Re. (4), I presume you refer to the minimap. Configurable zoom level would be nice, but I've never felt the need for it to be any different since the point is to get a birds eye of a large part of your file, so you can see the "patterns", rather than actually have it readable. You might want to post a suggestion on sublimetext.userecho.com/ and search for "minimap" while you're there since there are some other good minimap requests too.
I agree that Sublime's status bar should definitely have more API hooks for devs including some position and layout flexibility. There's a lot of real-estate doing nothing there right now. It could show eg. line endings and encoding, clickable for easy changing; a clock would be nice (I miss that from the Brief days); option to show CWD and full file path, and some of these things clickable to copy to the clipboard or paste straight into the doc. Just some thoughts
S | https://forum.sublimetext.com/t/my-feedback-after-usage/7921/1 | CC-MAIN-2016-07 | refinedweb | 696 | 62.78 |
Developing Backbone.js
Applications
Addy Osmani
Developing Backbone.js Applications
by Addy Osmani
Revision History for the :
2012-04-19 Early release revision 1
See for release details.
ISBN: 978-1-449-32825-2
1335306849
Table of Contents
Prelude .................................................................... vii
1.
Introduction ........................................................... 1
Fundamentals 2
MVC, MVP & Backbone.js 2
MVC 2
Smalltalk-80 MVC 2
MVC As We Know It 3
Models 4
Views 5
Controllers 8
Controllers in Spine.js vs Backbone.js 8
What does MVC give us?10
Delving deeper 10
Summary 11
MVP 11
Models, Views & Presenters 11
MVP or MVC?12
MVC, MVP and Backbone.js 13
Fast facts 15
Backbone.js 15
2.
The Basics ............................................................ 17
What is Backbone?17
Why should you consider using it?17
The Basics 17
Models 18
Views 21
Creating new views 21
What is el?22
Collections 23
iii
Underscore utility functions 25
Routers 25
Backbone.history 27
Namespacing 27
What is namespacing?28
Additional Tips 31
Automated Backbone Scaffolding 31
Is there a limit to the number of routers I should be using?32
Is Backbone too small for my application’s needs?32
3.
RESTful Applications .................................................... 33
Building RESTful applications with Backbone 33
Stack 1: Building A Backbone App With Node.js, Express, Mongoose and
MongoDB 33
Reviewing the stack 33
Practical 34
Practical Setup 40
Building Backbone.js Apps With Ruby, Sinatra, MongoDB and Haml 42
Introduction 42
What Is Sinatra?42
Getting Started With Sinatra 43
Templating And HAML 45
MongoDB Ruby Driver 47
Getting started 47
Practical 48
Installing The Prerequisites 48
Tutorial 50
Conclusions 57
4.
Advanced ............................................................. 59
Modular JavaScript 59
Organizing modules with RequireJS and AMD 59
Writing AMD modules with RequireJS 60
Keeping Your Templates External Using RequireJS And The Text Plugin 63
Optimizing Backbone apps for production with the RequireJS Optimizer 65
Practical: Building a modular Backbone app with AMD & RequireJS 67
Overview 67
Markup 68
Configuration options 69
Modularizing our models, views and collections 70
Decoupling Backbone with the Mediator and Facade patterns 75
Summary 75
Practical 76
iv | Table of Contents
Paginating Backbone.js Requests & Collections 82
Paginator’s pieces 83
Downloads And Source Code 83
Live Examples 84
Paginator.requestPager 86
1. Create a new Paginated collection 86
2: Set the model and base URL for the collection as normal 86
3. Map the attributes supported by your API (URL) 87
4. Configure the default pagination, query and sort details for the pag-
inator 87
5. Finally, configure Collection.parse() and we’re done 88
Convenience methods:89
Paginator.clientPager 89
1. Create a new paginated collection with a model and URL 89
2. Map the attributes supported by your API (URL) 90
3. Configure how to paginate data at a UI-level 90
4. Configure the rest of the request parameter default values 90
5. Finally, configure Collection.parse() and we’re done 91
Convenience methods:91
Views/Templates 91
Backbone & jQuery Mobile 94
Resolving the routing conflicts 94
Practical: A Backbone, RequireJS/AMD app with jQuery Mobile 95
Getting started 95
jQuery Mobile: Going beyond mobile application development 96
5.
Unit Testing ........................................................... 99
Unit Testing Backbone Applications With Jasmine 99
Introduction 99
Jasmine 99
Suites, Specs & Spies 101
beforeEach and afterEach() 104
Shared scope 104
Getting setup 105
TDD With Backbone 105
Models 105
Collections 108
Views 110
Initial setup 111
View rendering 113
Rendering with a templating system 116
Conclusions 118
Exercise 118
Table of Contents | v
Further reading 118
Unit Testing Backbone Applications With QUnit And SinonJS 119
Introduction 119
QUnit 119
Getting Setup 119
Assertions 120
Adding structure to assertions 124
Assertion examples 125
Fixtures 127
Asynchronous code 129
SinonJS 130
What is SinonJS?130
Stubs and mocks 133
Practical 135
Models 135
Collections 137
Views 138
Events 139
App 141
Further Reading & Resources 142
6.
Resources ........................................................... 143
7.
Conclusions .......................................................... 145
vi | Table of Contents
Prelude
Welcome to my (in-progress) book about the Backbone.js framework for structuring
JavaScript applications. It’s released under a Creative Commons Attribution-Non-
Commercial-ShareAlike 3.0 Unported license meaning you can both grab a copy of the
book for free or help to further improve it.
I’m very pleased to announce that this book will be out in physical form in a few months
time via O’Reilly Media. Readers will have the option of purchasing the latest version
in either print or a number of digital formats then or can grab a recent version from this
repository.
Corrections to existing material are always welcome and I hope that together we can
provide the community with an up-to-date resource that is of help. My extended thanks
go out to Jeremy Ashkenas for creating Backbone.js and these members of the com-
munity for their assistance tweaking this project.
I hope you find this book helpful!
vii
CHAPTER 1Introduction.
Maturity in software (framework) development isn’t simply about how long a frame-
work has been around. It’s about how solid the framework is and more importantly
how well it’s evolved to fill its role. Has it become more effective at solving common
problems? Does it continue to improve as developers build larger and more complex
applications with it?
In this book, I will be covering the popular Backbone.js, which I consider the best of
the current family of JavaScript architectural frameworks.
Topics will include MVC theory and how to build applications using Backbone’s mod-
els, views, collections and routers. I’ll also be taking you through advanced topics like
modular development with Backbone.js and AMD (via RequireJS), how to build ap-
plications infor-
mation that can help those developing real-world apps with Backbone. If you come
across a section or topic which you think could be improved or expanded on, please
feel free to submit a pull-request. It won’t take long and you’ll be helping other devel-
opers avoid problems you’ve run into before.
1
Fundamentals
In this section we are going to cover the context into which a framework like Back-
bone. Al-
though im-
proved application organization through a separation of concerns. It enforces the iso-
lation of business data (Models) from user interfaces (Views), with a third component
(Controllers) traditionally present to manage logic, user-input and
has changed quite heavily since the days of its origin. Back in the 70’s, graphical user-
interfaces were far and few between. An approach known as Separated Presentation
began to be used as a means to make a clear division between domain objects which
modeled concepts in the real world (e.g a photo, a person) and the presentation objects
which were rendered to the user’s screen.
2 | Chapter 1: Introduction
The Smalltalk-80 implementation of MVC took this concept further and had an ob-
jective:
• A Domain element was known as a Model and were ignorant of the user-interface
(Views and Controllers)
• Presentation was taken care of by the View and the Controller, but there wasn’t
just a single view and controller. A View-Controller pair was required for each
element being displayed on the screen and so there was no true separation between
them
• The Controller’s role in this pair was handling user input (such as key-presses and
click events), doing something sensible with them.
• The Observer pattern was relied upon for updating the View whenever the Model
changed
Developers are sometimes surprised when they learn that the Observer pattern (nowa-
days pop-
ular Ruby on Rails is an implementation of a web application framework based on
MVC for the Ruby language. JavaScript now has a number of MVC frameworks, in-
cluding:
MVC As We Know It | 3
Models
Models manage the data for an application. They are concerned with neither the user-
interface nor presentation layers, but instead represent structured data that an appli-
cation may require. When a model changes (e.g when it is updated), it will typically
notify its observers (e.g views, a concept we will cover shortly) that a change has oc-
curred so that they may react accordingly.
To understand models better, let us imagine we have a JavaScript photo gallery appli-
cation.() {
}
}); some-
where, for example in a web browser’s localStorage data-store or synchronized with a
database.
A model may at-
tribute.,
4 | Chapter 1: Introduction
should any model it contains change. This avoids the need to manually observe indi-
vidual model instances.
Here’s how we might group Photo models into a simplified Backbone Collection:());
}
});
If you read older texts on MVC, you may come across a description of models as also
managing application “state”.
Views are a visual representation of models that present a filtered view of their current
state. A view typically observes a model and is notified when the model changes, al-
lowing the view to update itself accordingly. Design pattern literature commonly refers
to views as “dumb”, given that their knowledge of models and controllers in an appli-
cation is limited.. Below we can see
a function that creates a single Photo view, consuming both a model instance and a
controller instance.
MVC As We Know It | 5
We define a render() utility within our view which is responsible for rendering the
contents of the photoModel using a JavaScript templating engine (Underscore templat-
ing) and updating the contents of our view, referenced by photoEl.
The photoModel then adds our render() callback as one of its subscribers, so that
through the Observer pattern it can trigger the view to update when the model changes.
You may wonder where user interaction comes into play here. When users click on any
elements within the view, it’s not the view’s responsibility to know what to do next. A
Controller makes this decision. In our sample implementation, this is achieved by
adding an event listener to photoEl which will delegate handling the click behavior back
to the controller, passing the model information along with it in case it’s needed.
The benefit of this architecture is that each component plays its
6 | Chapter 1: Introduction. De-
velopers using this technique often find themselves iterating through their data, wrap-
ping Handlebars.js or Mustache) are often used to
define templates for views as HTML markup containing template variables. These
template blocks can be either stored externally or within script tags with a custom type
(e.g “text/template”). Variables are delimited using a variable syntax (e.g {{name}}).
Javascript template libraries typically accept data in JSON, and the grunt work of pop-
ulating templates with data is taken care of by the framework itself. This has a several
benefits, particularly when opting to store templates externally as this can let applica-
tions load templates dynamically on an as-needed basis.
Let’s compare two examples of HTML templates. One is implemented using the pop-
ular Handlebars.js library, and the other uses Underscore’s “micro> inde-
pendent views required the use of a page refresh. In single-page JavaScript applications,
MVC As We Know It | 7.
Controllers
Controllers are an intermediary between models and views which are classically re-
sponsible.
It’s with controllers that most JavaScript MVC frameworks depart from this interpre-
tation at Spine.js:
8 | Chapter 1: Introduction
In this example, we’re going to have a controller called PhotosController which will be
in charge of individual photos in the application. It will ensure that when the view
updates (e.g a user edited the photo meta-data) the corresponding model does too.
(Note: We won’t be delving heavily into Spine.js beyond this example, but it’s worth
looking at it to learn more about Javascript frameworks in general.)
//,
MVC As We Know It | 9 );
}
}):
What does MVC give us?
To summarize, the separation of concerns in MVC facilitates modularization of an
application’s functionality and enables:
• Easier overall maintenance. When updates need to be made to the application it
is clear whether the changes are data-centric, meaning changes to models and pos-
sibly controllers, or merely visual, meaning changes to views.
• Decoupling models and views means that it’s straight-forward to write unit tests
for business logic
• Duplication of low-level model and controller code is eliminated across the appli-
cation
•.
10 | Chapter 1: Introduction
As we’ve discussed, models represent application data, while views handle what the
user is presented on screen. As such, MVC relies on Pub/Sub for some of its core com-
munication (something that surprisingly isn’t covered in many articles about the MVC
pattern). When a model is changed it “publishes” to the rest of the application that it
has been updated. The “subscriber”–generally a Controller–then updates the view ac-
cordingly. re-
lationship. Controllers facilitate views to respond to different user input and are an
example of the Strategy pattern.
Summary
Having reviewed the classical MVC pattern, your should now understand how it allows
developers to cleanly separate concerns in an application. You should also now appre-
ciate compo-
nents,.
MVP | 11 Con-
trollers appli-
cation Java-
Script, we’re using it more as more a protocol than an explicit interface here. It’s tech-
nically) introduce this idea of a Supervising Controller to Backbone..
12 | Chapter 1: Introduction
Depending on the implementation, MVP may be more easy to automatically unit test
than MVC. The reason often cited for this is that the presenter can be used as a complete
mock of the user-interface and so it can be unit tested independent of other compo-
nents. sepa-
rates Backbone views out into their own distinct components, she needs something to
actually assemble them for her. This could either be a controller route (such as a Back
bone.Router, covered later in the book) or a callback in response to data being fetched.
That said, some developers do however feel that Backbone.js better fits the description
of MVP than it does MVC . Their view is that:
• The presenter in MVP better describes the Backbone.View (the layer between View
templates and the data bound to it) than a controller does
• The model fits Backbone.Model (it isn’t that different from the classical MVC
“Model”)
• ach-
ieve two purposes: both rendering atomic components and assembling those compo-
nents rendered by other views.
We’ve also seen that in Backbone the responsibility of a controller is shared with both
the Backbone.View and Backbone.Router and in the following example we can actually
see that aspects of that are certainly true.
MVC, MVP and Backbone.js | 13
Here, our Backbone PhotoView uses the Observer pattern to “subscribe” to changes to
a View’s model in the line this.model.on(.on('change', this.render);
this.model.on( framework that just works
well. Call it the Backbone way, MV* or whatever helps reference its flavor of appli-
cation architecture.
14 | Chapter 1: Introduction.
Fast facts
Backbone.js
• Core components: Model, View, Collection, Router. Enforces its own flavor of
MV*
• Good documentation, with more improvements on the way
• Used by large companies such as SoundCloud and Foursquare to build non-trivial
applications
• Event-driven communication between views and models. As we’ll see, it’s relatively
straight-forward to add event listeners to any attribute in a model, giving developers
fine-grained control over what changes in the view
• Supports data bindings through manual events or a separate Key-value observing
(KVO) library
• Great support for RESTful interfaces out of the box, so models can be easily tied
to a backend
• Extensive eventing system. It’s trivial to add support for pub/sub in Backbone
• Prototypes are instantiated with the new keyword, which some developers prefer
• Agnostic about templating frameworks, however Underscore’s micro-templating
is available by default. Backbone works well with libraries like Handlebars
• Doesn’t support deeply nested models, though there are Backbone plugins such as
this which can help
• Clear and flexible conventions for structuring applications. Backbone doesn’t force
usage of all of its components and can work with only those needed.
Fast facts | 15
CHAPTER 2The Basics-
ber:
• Organize the structure to your application
• Simplify server-side persistence
• Decouple the DOM from your page’s data
• Model data, views and routers in a succinct manner
• Provide DOM, model and collection synchronization
The Basics
In this section, you’ll learn the essentials of Backbone’s models, views, collections and
routers, as well as about using namespacing to organize your code. This isn’t meant as
17
a replacement for the official documentation, but it will help you understand many of
the core concepts behind Backbone before you start building applications with it.
• Models
• Collections
• Routers
• Views
• Namespacing
Models.on(();
18 | Chapter 2: The Basics = “A' });
The Basics | 19.on(.on("change:title", function(){
var title = this.get("title");
console.log("My title has been changed to.. " + title);
});
},
20 | Chapter 2: The Basics.on("error", function(model, error){
console.log(error);
});
}
});
var myPhoto = new Photo();
myPhoto.set({ title: "On the beach" });
//logs Remember to set a source for your image!
Views, al-
lowing the view to always be up to date without requiring a full page refresh.
Creating new views
Similar to the previous sections, creating a new view is relatively straight-forward. To
create a new View, simply extend Backbone.View. I’ll explain this code in detail below:
Views | 21 your()
22 | Chapter 2: The Basics .dele
gate() to provide instant support for event delegation but goes a little further, extending
it so that this always refers to the current view object. The only thing to really keep in
mind is that any string callback supplied to the events attribute must have a corre-
sponding function with the same name within the scope of your view.
Collections
Collections are sets of Models and are created by extending Backbone.Collection.
Normally, when creating a collection you’ll also want to pass through a property spec-
ifying.
Collections | 23 ex-
ample:
var PhotoCollection = new Backbone.Collection();
PhotoCollection.on(.on());
};
24 | Chapter 2: The Basics
Resetting/Refreshing Collections
Rather than adding or removing models individually, you might occasionally wish to
update an entire collection at once. Collection.reset() allows us to replace an entire
collection with new models as follows:
javascript PhotoCollection.reset([ {title: "My trip to Scotland", src: "scot
land-trip.jpg"}, {title: "The flight from Scotland", src: "long-flight.jpg"},
{title: "Latest snap of lock-ness", src: "lockness.jpg"}]); Note that using Col
lection.reset() doesn’t fire any add or remove events. A reset event is fired instead..
Routers appli-
cation that requires a GalleryRouter.
Note the inline comments in the code example below as they continue the rest of the
lesson on routers.
var GalleryRouter = Backbone.Router.extend({
/* define the route and function maps for this router */
Routers | 25){
var page_number = page || 1;
console.log("Page number: " + page_number + " of the results for " + query);
},
downloadPhoto: function(id, path){
},
defaultRoute: function(other){
26 | Chapter 2: The Basics
console.log("Invalid. You attempted to reach:" + other);
}
});
/* Now that we have a router setup, remember to instantiate it*/
var myGalleryRouter = new GalleryRouter();
As of Backbone 0.5+, it’s possible to opt-in for HTML5 pushState support via win
dow.history.pushState. This permits you to define routes such as-
junkie.com/just/an/example. frag-
ment
When learning how to use Backbone, an important and commonly overlooked area by
tutorials is namespacing. If you already have experience with namespacing in Java-
Script, the following section will provide some advice on how to specifically apply
concepts you know to Backbone, however I will also be covering explanations for be-
ginners to ensure everyone is on the same page.
Namespacing | 27 “citizen” of the global namespace, it’s also imperative that you do
your best to similarly not prevent other developer’s scripts executing due to the same
issues.
JavaScript doesn’t really have built-in support for namespaces like other languages,
however it does have closures which can be used to achieve a similar effect.
In this section we’ll be taking a look shortly at some examples of how you can name-
space your models, views, routers and other components specifically. The patterns we’ll
be examining are:
• Single global variables
• Object Literals
• Nested namespacing {
PhotoView: Backbone.View.extend({ .. }),
GalleryView: Backbone.View.extend({ .. }),
AboutView: Backbone.View.extend({ .. });
//etc.
};
})();
Here we can return a set of views, but the same technique could return an entire col-
lection of models, views and routers depending on how you decide to structure your
application. Although this works for certain situations, the biggest challenge with the
single global variable pattern is ensuring that no one else has used the same global
variable name as you have in the page.
28 | Chapter 2: The Basics
One solution to this problem, as mentioned by Peter Michaux, is to use prefix name-
spacing. It’s a simple concept at heart, but the idea is you select a common prefix name
(in this example, myApplication_) and then define any methods, variables or other ob-
jects after the prefix.
var myApplication_photoView = Backbone.View.extend({}),
myApplication_gallery):
Namespacing | 29
var myGalleryViews = myGalleryViews || {};
myGalleryViews.photoView = Backbone.View.extend({});
myGalleryViews.gallery, Ya-
hoo’s YUI uses the nested object namespacing pattern extensively:
YAHOO.util.Dom.getElementsByClassName('test');
Yahoo’s YUI uses the nested object namespacing pattern regularly and even Docu-
mentCloud (the creators of Backbone) use the nested namespacing pattern in their main
applications. A sample implementation of nested namespacing with Backbone may
look like this:
var galleryApp = galleryApp || {};
// perform similar check for nested children
30 | Chapter 2: The Basics
galleryApp.routers = galleryApp.routers || {};
galleryApp.model = galleryApp.model || {};
galleryApp.model.special = galleryApp.model.special || {};
// routers
galleryApp.routers.Workspace = Backbone.Router.extend({});
galleryApp.routers.PhotoSearch = Backbone.Router.extend({});
// models
galleryApp.model.Photo = Backbone.Model.extend({});
galleryApp.model.Comment = Backbone.Model.extend({});
// special models
galleryApp.model.special.Admin = Backbone.Model.extend({});
This is readable, clearly organized, and is a relatively safe way of namespacing your
Backbone application. The only real caveat however is that it requires your browser’s
JavaScript engine to first locate the galleryApp object, then dig down until it gets to the
function you’re calling. However, developers such as Juriy Zaytsev (kangax) have tested
and found the performance differences between single object namespacing vs the “nes-
ted” approach to be quite negligible.
Recommendation
Reviewing the namespace patterns above, the option that I prefer when writing Back-
bone applications is nested object namespacing with the object literal pattern.
Single global variables may work fine for applications that are relatively trivial. How-
ever, larger codebases requiring both namespaces and deep sub-namespaces require a
succinct solution that’s both readable and scalable. I feel this pattern achieves both of
these objectives and is a good choice for most Backbone development.
Additional Tips
Automated Backbone Scaffolding
Scaffolding can assist in expediting how quickly you can begin a new application by
creating the basic files required for a project automatically. If you enjoy the idea of
automated MVC scaffolding using Backbone, I’m happy to recommend checking out
a tool called Brunch.
It works very well with Backbone, Underscore, jQuery and CoffeeScript and is even
used by companies such as Red Bull and Jim Beam. You may have to update any third
party dependencies (e.g. latest jQuery or Zepto) when using it, but other than that it
should be fairly stable to use right out of the box.
Brunch can be installed via the nodejs package manager and is easy to get started with.
If you happen to use Vim or Textmate as your editor of choice, you’ll be happy to know
that there are Brunch bundles available for both.
Additional Tips | 31
Is there a limit to the number of routers I should be using?
Andrew de Andrade has pointed out that DocumentCloud themselves usually only use
a single router in most of their applications. You’re very likely to not require more than
one or two routers in your own projects as the majority of your application routing can
be kept organized in a single controller without it getting unwieldy.
Is Backbone too small for my application’s needs?
If you find yourself unsure of whether or not your application is too large to use Back-
bone, I recommend reading my post on building large-scale jQuery & JavaScript ap-
plications or reviewing my slides on client-side MVC architecture options. In both, I
cover alternative solutions and my thoughts on the suitability of current MVC solutions
for scaled application development.
Backbone can be used for building both trivial and complex applications as demon-
strated by the many examples Ashkenas has been referencing in the Backbone docu-
mentation. As with any MVC framework however, it’s important to dedicate time to-
wards planning out what models and views your application really needs. Diving
straight into development without doing this can result in either spaghetti code or a
large refactor later on and it’s best to avoid this where possible.
At the end of the day, the key to building large applications is not to build large appli-
cations in the first place. If you however find Backbone doesn’t cut it for your require-
ments I strongly recommend checking out JavaScriptMVC or SproutCore as these both
offer a little more than Backbone out of the box. Dojo and Dojo Mobile may also be of
interest as these have also been used to build significantly complex apps by other de-
velopers.
32 | Chapter 2: The Basics
CHAPTER 3RESTful Applications
Building RESTful applications with Backbone
In this section of the book, we’re going to take a look at developing RESTful applica-
tions using Backbone.js and modern technology stacks. When the data for your back-
end is exposed through a purely RESTful API, tasks such as retrieving (GET), creating
(POST), updating (PUT) and deleting (DELETE) models are made easy through Back-
bone’s Model API. This API is so intuitive in fact that switching from storing records
in a local data-store (e.g localStorage) to a database/noSQL data-store is a lot simpler
than you may think.
Stack 1: Building A Backbone App With Node.js, Express,
Mongoose and MongoDB
The first stack we’ll be looking at is:
• Node.js
• Express
• Mongoose
• and MongoDB
with Jade used optionally as a view/templating engine.
Reviewing the stack
As you may know, node.js is an event-driven platform (built on the V8 runtime), de-
signed for writing fast, scalable network applications. It’s reasonably lightweight, effi-
cient and great for real-time applications that are data-intensive.
33
Express is a small web-development framework written with node.js, based on Sina-
tra. It supports a number of useful features such as intuitive views, robust routing and
a focus on high performance.
Next on the list are MongoDB and Mongoose. MongoDB is an open-source, document-
oriented database store designed with scalability and agility in mind. As a noSQL da-
tabase, rather than storing data in tables and rows (something we’re very used to doing
with relational databases), with MongoDB we instead store JSON-like documents us-
ing dynamic schemas. One of the goals of Mongo is to try bridging the gap between
key-value stores (speed, scalability) and relational databases (rich functionality).
Mongoose is a JavaScript library that simplifies how we interact with Mongo. Like
Express, it’s designed to work within the node.js environment and tries to solve some
of the complexities with asynchronous data storage by offering a more user-friendly
API. It also adds chaining features into the mix, allowing for a slightly more expressive
way of dealing with our data.
Jade is a template engine influenced by Haml (which we’ll be looking at later). It’s
implemented with JavaScript (and also runs under node). In addition to supporting
Express out of the box, it boasts a number of useful features including support for
mixins, includes, caching, template inheritance and much more. Whilst abstractions
like Jade certainly aren’t for everyone, our practical will cover working both with and
without it.
Practical
For this practical, we’re going to once again look at extending the popular Backbone
Todo application. Rather than relying on localStorage for data persistence, we’re going
to switch to storing Todos in a MongoDB document-store instead. The code for this
practical can be found in practicals\stacks\option2
app.js
(See here for the source)
We must first include the node dependencies required by our application. These are
Express, Mongoose and Path (a module containing utilities for dealing with file paths.
var application_root = __dirname,
express = require("express"),
path = require("path"),
mongoose = require('mongoose');
Next, create a new Express server. express.createServer() is a simple way of creating
an instance of express.HTTPServer, which we’ll be using to pass in our routes.
var app = express.createServer();
After this, connect Mongoose up to a database (in our case, localhost should suffice).
Should you require the ability to pass in authentication information, here’s a sample
34 | Chapter 3: RESTful Applications
containing all of the supported URL parameters: mongodb://[username:pass
word@]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/[database][?options]]
mongoose.connect('mongodb://localhost/my_database');
A Mongoose model for any Todo item can now be easily defined by passing a schema
instance to mongoose.model. In our case the schema covers a Todo item’s text content,
its done state and order position in the overall Todo list.
var Todo = mongoose.model('Todo', new mongoose.Schema({
text: String,
done: Boolean,
order: Number
}));
The configure() methods allows us to setup what we need for the current environment
with our Express server. Note that lower down in the configuration are two view/view
related lines. The last one explicitly sets the viewing/templating engine to be used as
Jade app.set('view engine', 'jade'). We can avoid these if we wish to use plain
HTML/JS for our templates instead.
app.configure(function(){
// the bodyParser middleware parses JSON request bodies
app.use(express.bodyParser());
app.use(express.methodOverride());
app.use(app.router);
app.use(express.static(path.join(application_root, "public")));
app.use(express.errorHandler({ dumpExceptions: true, showStack: true }));
app.set('views', path.join(application_root, "views"));
app.set('view engine', 'jade')
});
Should you prefer to switch out Jade for an alternative view engine, this can be done
fairly trivially. See the section under “Templating” here:
node/wiki/modules. For example, to switch to EJS, you would simply write
app.set('view engine', 'ejs')
Express makes use of common HTTP verbs (get, put, post etc.) to provide easy to use,
expressive routing API based on CRUD (Create, Read, Update and Delete). Below for
example, we can define what happens when the browser requests the root “/”. As a
trivial route in this application, it doesn’t do anything particularly exciting, however
getters typically read or retrieve data.
app.get('/', function(req, res){
res.send('Hello World');
});
Onto something a little more useful and in our next route, navigating to “/todo” will
actually render our Jade view “todo.jade”, as seen in the callback. Additional config-
uration values can be passed as the second parameter, such as the custom title specified
below.
Stack 1: Building A Backbone App With Node.js, Express, Mongoose and MongoDB | 35
app.get('/todo', function(req, res){
res.render('todo', {title: "Our sample application"});
});
Next, we can see the first of our “/api/” routes.
app.get('/api/todos', function(req, res){
return Todo.find(function(err, todos) {
return res.send(todos);
});
});
The callback to our next route supports querying for todos based on a specific ID. The
route string itself (once compiled) will be converted from “/api/todos/:id” to a regular
expression. As you might have guessed, this is a hint that routes can also be regular
expression literals if we wished to do something more complex.
app.get('/api/todos/:id', function(req, res){
return Todo.findById(req.params.id, function(err, todo) {
if (!err) {
return res.send(todo);
}
});
});
Similarly, we want to support updating todos based on a specific ID as well. The fol-
lowing allows us to query a todo by ID and then update the values of it’s three attributes
(text, done, order) easily.
app.put('/api/todos/:id', function(req, res){
return Todo.findById(req.params.id, function(err, todo) {
todo.text = req.body.text;
todo.done = req.body.done;
todo.order = req.body.order;
return todo.save(function(err) {
if (!err) {
console.log("updated");
}
return res.send(todo);
});
});
});
We’ve so far covered requesting todos and updating them, but a core part of the ap-
plication requires us to insert (or add) new todos to our data-store. Below we can create
new Todo models and simply save them.
app.post('/api/todos', function(req, res){
var todo;
todo = new Todo({
text: req.body.text,
done: req.body.done,
order: req.body.order
});
todo.save(function(err) {
if (!err) {
36 | Chapter 3: RESTful Applications
return console.log("created");
}
});
return res.send(todo);
});
We of course also want to support deleting todos (e.g if a todo has been “cleared”, it
should be deleted). This also works based on a specific todo ID.
app.delete('/api/todos/:id', function(req, res){
return Todo.findById(req.params.id, function(err, todo) {
return todo.remove(function(err) {
if (!err) {
console.log("removed");
return res.send('')
}
});
});
});
Finally, this last line is to ensure we’re only listening on the port app.js is running.
app.listen(3000);
script.js - updating our Backbone.js app
In the /public/js folder of options 1 (HTML templates) and 2 (Jade) for the practical,
you’ll find a version of the Backbone Todo app originally by Jerome Gravel-Niquet.
Let’s pay attention to script.js. In order to change the application to work with our new
back-end, we’ll need to make some very minor changes to this.
Reviewing window.TodoList (a Backbone Collection), you’ll notice that it has a property
called localStorage, which uses the Backbone localStorage adapter in order to facilitate
storing data using the browser’s localStorage features.
window.TodoList = Backbone.Collection.extend({
// Reference to this collection's model.
model: Todo,
// Save all of the todo items under the `"todos"` namespace.
// Typically, this should be a unique name within your application
localStorage: new Store("todos"), | https://www.techylib.com/el/view/bolivialodge/developing_backbone.js_applications_addy_osmani | CC-MAIN-2018-26 | refinedweb | 5,736 | 55.24 |
Exporting data from a large multi-realm Zulip server¶
Draft status¶
This is a draft design document considering potential future refinements and improvements to make large migrations easier going forward, and is not yet a set of recommendations for Zulip systems administrators to follow.
Overview¶
Zulip offers an export tool,
management/export.py, which works well
to export the data for a single Zulip realm, and which is your best
choice if you’re migrating a Zulip realm to a new server.
This document supplements the explanation in
management/export.py,
but here we focus more on the logistics of a big conversion of a
multi-realm Zulip installation. (For some historical perspective, this
document was originally begun as part of a big Zulip cut-over in
summer 2016.)
There are many major operational aspects to doing a conversion. I will list them here, noting that several are not within the scope of this document:
Get new servers running.
Export data from the old DB.
Export files from Amazon S3.
Import files into new storage.
Import data into new DB.
Restart new servers.
Decommission old server.
This document focuses almost entirely on the export piece. Issues with getting Zulip itself running are out of scope here; see the production installation instructions. As for the import side of things, we only touch on it implicitly. (My reasoning was that we had to get the export piece right in a timely fashion, even if it meant we would have to sort out some straggling issues on the import side later.)
Exporting multiple realms’ data when moving to a new server¶
The main exporting tools in place as of summer 2016 are below:
We can export single realms (but not yet limit users within the realm).
We can export single users (but then we get no realm-wide data in the process).
We can run exports simultaneously (but have to navigate a bunch of /tmp directories).
Things that we still may need:
We may want to export multiple realms simultaneously.
We may want to export multiple single users simultaneously.
We may want to limit users within realm exports.
We may want more operational robustness/convenience while doing several exports simultaneously.
We may want to merge multiple export files to remove duplicates.
We have a few major classes of data. They are listed below in the order
that we process them in
do_export_realm():
Cross Realm Data¶
Client/zerver_userprofile_cross_realm
This includes
Client and three bots.
Client is unique in being a fairly core table that is not tied to
UserProfile or
Realm (unless you somewhat painfully tie it back to
users in a bottom-up fashion though other tables).
Recipient Data¶
Recipient/Stream/Subscription/Huddle.
These tables are tied back to users, but they introduce complications when you try to deal with multi-user subsets.
Summary¶
Here are the same classes of data, listed in roughly decreasing order of riskiness:
Message Data (sheer volume/lack of time/security)
File-Related Data (S3/security/lots of moving parts)
Recipient Data (complexity/security/cross-realm considerations)
Cross Realm Data (duplicate ids)
Disjoint User Data
Public Realm Data
(Note the above list is essentially in reverse order of how we process the data, which isn’t surprising for a top-down approach.)
The next section of the document talks about risk factors.
Risk Mitigation¶
Generic considerations¶
We have two major mechanisms for getting data:
Top Down¶
Get realm data, then all users in realm, then all recipients, then all messages, etc.
The problem with the top-down approach will be filtering. Also, if errors arise during top-down passes, it may be time consuming to re-run the processes.
Approved Transfers¶
We have not yet integrated the approved-transfer model, which tells us which users can be moved.
Risk factors broken out by data categories¶
Message Data¶
models:
UserMessage.
assets:
messages-*.json, subprocesses, partial files
Rows in the
Message model depend on
Recipient/UserProfile.
Rows in the
UserMessage model depend on
UserProfile/Message.
The biggest concern here is the sheer volume of data, with security being a close second. (They are interrelated, as without security concerns, we could just bulk-export everything one time.)
We currently have these measures in place for top-down processing:
chunking
multi-processing
messages are filtered by both sender and recipient
File Related Data¶
models:
Attachment
assets: S3,
attachment.json,
uploads-temp/, image files in
avatars/, assorted files in
uploads/,
avatars/records.json,
uploads/records.json,
zerver_attachment_messages
When it comes to exporting attachment data, we have some minor volume issues, but the main concern is just that there are lots of moving parts:
S3 needs to be up, and we get some metadata from it as well as files.
We have security concerns about copying over only files that belong to users who approved the transfer.
This piece is just different in how we store data from all the other DB-centric pieces.
At import time we have to populate the
m2mtable (but fortunately, this is pretty low risk in terms of breaking anything.)
Recipient Data¶
models:
Recipient/Stream/Subscription/Huddle
assets:
realm.json,
(user,stream,huddle)_(recipient,subscription)
This data is fortunately low to medium in volume. The risk here will come from model complexity and cross-realm concerns.
From the top down, here are the dependencies:
Recipientdepends on
UserProfile
Subscriptiondepends on
Recipient
Streamcurrently depends on
Realm(but maybe it should be tied to
Subscription)
Huddledepends on
Subscriptionand
UserProfile
The biggest risk factor here is probably just the possibility that we
could introduce some bug in our code as we try to segment
Recipient
into user, stream, and huddle components, especially if we try to
handle multiple users or realms. I think this can be largely
mitigated by the new
Config approach.
And then we also have some complicated
Huddle logic that will be
customized regardless. The fiddliest part of the
Huddle logic is
creating the set of
unsafe_huddle_recipient_ids.
Last but not least, if we go with some hybrid of bottom-up and top-down, these tables are neither close to the bottom nor close to the top, so they may have the most fiddly edge cases when it comes to filtering and merging.
Recommendation: We probably want to get a backup of all this data that is very simply bulk-exported from the entire DB, and we should obviously put it in a secure place.
Cross Realm Data¶
models:
Client
assets:
realm.json, three bots (
notification/
id_maps
The good news here is that
Client is a small table, and there are
only three special bots.
The bad news is that cross-realm data complicates everything else, and we have to avoid database ID conflicts.
If we use bottom-up approaches to load small user populations at a
time, we may have merging issues here. We will need to
consolidate IDs either by merging exports in
/tmp or handle it at
import time.
For the three bots, they live in
zerver_userprofile_crossrealm, and
we re-map their IDs on the new server.
Recommendation: Do not sweat the exports too much. Deal with all the
messiness at import time, and rely on the tables being really small.
We already have logic to catch
Client.DoesNotExist exceptions, for
example. As for possibly missing messages that the welcome bot and
friends have sent in the past, I am not sure what our risk profile is
there, but I imagine it is relatively low.
Disjoint User Data¶
models:
UserProfile/UserActivity/UserActivityInterval/UserPresence
assets:
realm.json,
api_key,
avatar salt,
id_maps
On the DB side this data should be fairly easy to deal with. All of these tables are basically disjoint by user profile ID. Our biggest risk is remapped user ids at import time, but this is mostly covered in the section above.
We have code in place to exclude
password and
api_key from
UserProfile rows. The import process calls
set_unusable_password(). | https://zulip.readthedocs.io/en/latest/subsystems/conversion.html | CC-MAIN-2019-47 | refinedweb | 1,314 | 54.32 |
0
Hi,
while doing my assignment im somehow stucked somewhere which i didnt know why and i need some help. i have jus started learning abt c++. so im jus using some basic syntax
#include<iostream> using namespace std; int main() { int selclass,i,position; char ch; int seats[100]={0}; //array while(true) { cout<<"Choose your class\n"; cout<<"1.Business Class\n"; cout<<"2.First Class\n"; cout<<"3.Economic Class\n"; cin>>selclass; switch(selclass) { switch(selclass) { case 1: cout<<"Seats available \n"; for(i=1;i<=20;i++) { if (seats[i] ==0) cout<<i<<" "; } cout<<"\nChoose your preferred seat\n"; cin>>position; //User's selected seat if (position > 20) { cout<<"Seat Number: "<<position<<" is not available for Business Class\n"; } else{ if (seats[position]=0) cout<<"You have booked "<<position<<".Thank you\n"; //this sentence dont appear seats[position]=1; //to change the array from 0 to 1 cout<<"You have booked "<<position<<".Thank you\n"; //this sentence appear if this line is added in but my array doesnt work } break;
i will require to add 1 more else at the very bottom for users who have selected an occupied seat. Please help | https://www.daniweb.com/programming/software-development/threads/180298/cout-did-not-appear-and-nesting-if-else | CC-MAIN-2017-39 | refinedweb | 197 | 60.55 |
Scale Image to Fit Page
This example shows, for PDF and Word reports, how to scale a large image to fit on a page.
Import the DOM and Report API packages so you do not have to use long, fully-qualified class names.
import mlreportgen.dom.* import mlreportgen.report.*
Create and open a report.
% To create a Word report, change the output type from "pdf" to "docx". rpt = Report("myreport","pdf"); open(rpt);
Specify an image that is too large to fit on the page.
imgPath = which("landOcean.jpg");
Add a heading to the report.
heading = Heading1("Unscaled Image"); add(rpt,heading);
Add the image to the report using the DOM Image class.
img1 = Image(imgPath); add(rpt,img1);
Add a heading to the report.
heading = Heading1("Image Scaled to Fit on a Page"); add(rpt,heading);
Use the DOM ScaleToFit format to scale the image to fit on the page and then, add the scaled image to the report.
img2 = Image(imgPath); img2.Style = [img2.Style {ScaleToFit}]; add(rpt,img2);
Close and view the report.
close(rpt); rptview(rpt); | https://fr.mathworks.com/help/rptgen/ug/scale-image-to-fit-page.html | CC-MAIN-2022-33 | refinedweb | 180 | 65.52 |
Have you ever wondered if there is a programmatic way to detect all the SQL server instances and services installed on a machine. Well, worry no more as the code below will do exactly that. There are 2 ways to go about this :
Method 1 – For the Programmer
The code below is written in C#.
1) Create a new Visual C# Windows Application project.
2) Add a RichTextBox control to your Form1.
3) Add a Button control to your Form1 called GetmeSQL.
4) In the Form1.cs page, add the following code.
//Import the Service namespace
using System.ServiceProcess;
5) Right-click on the Project in “Solution Explorer” -> Add Reference. Choose System.ServiceProcess and say OK.
6) Double-click on GetmeSQL button to take you to the code window and then copy-past the code given below.
private void GetmeSQL_Click(object sender, EventArgs e)
{
string servicename = "MSSQL";
string servicename2 = "SQLAgent";
string servicename3 = "SQL Server";
string servicename4 = "msftesql";
string serviceoutput = string.Empty;
ServiceController[] services = ServiceController.GetServices();
foreach (ServiceController service in services)
{
if (service == null)
continue;;
}
}
if (serviceoutput == "")
{
serviceoutput += "There are no SQL Server instances present on this machine!" + System.Environment.NewLine;
}
richTextBox1.Text = serviceoutput;
}
7) Now build your project and bingo ! Here is how it looks :-
Method 2
Copy the code given below and save it as Filename.vbs
strComputer = "."
Set objWMIService = GetObject("winmgmts:\\" & strComputer & "\root\Microsoft\SqlServer\ComputerManagement")
Set colItems = objWMIService.ExecQuery( "SELECT * FROM SqlService",,48)
For Each objItem in colItems
Wscript.Echo "———————————–"
Wscript.Echo "SqlService instance"
Wscript.Echo "———————————–"
Wscript.Echo "DisplayName: " & objItem.DisplayName
Wscript.Echo "ServiceName: " & objItem.ServiceName
Wscript.Echo "SQLServiceType: " & objItem.SQLServiceType
To execute above script run it from command prompt using c:\>cscript filename.vbs or just double-click on the script.
The Service Types are documented here ->
Method #1 will work for SQL Server 2000/2005/2008 and it can enumerate all SQL services (Database/Reporting/Analysis/Integration/FullText/Browser/Agent/VSS), whereas Method #2 works only for SQL 2005. It can be tweaked to make use of the namespace – root\Microsoft\SqlServer\ComputerManagement10 to get it to work for SQL Server 2008.
Sudarshan Narasimhan,
Technical Lead, Microsoft Sql Server
PingBack from
Wouldn’t the first method potentially result in false positives? For example, the default service name for the MySQL server is "MySQL", which contains the string "SQL".
David,
Yes you’re right. I am just looking for the keyword "SQL" in the service name. You can modify the code as given below to avoid any false positivies. Now, we will still all SQL services (browser,agent,fulltext) but avoid any non-MSSQL services like MySQL etc. Thanks for bringing this to my attention.
// Add these 3 new variables
string servicename2 = "SQLAgent";
string servicename3 = "SQL Server";
string servicename4 = "msftesql";
// Replace the IF condition given above with this;
}
string servicename3 = "SQL Server"; does not work for SQL 2005 Express
you may use string servicename3 = "MSSQL$" instead to find out the instance of the installed server, but it wont work for 2000.
sc query state= all | find "DISPLAY_NAME: SQL"
sc query state= all | find "MSSQL"
…
Don't use scrips unless it's really necessary.
You need fast and easy to remember solutions, ready to use on every host you login.
In any case you can use sc tool to get info about remote systems too. sc /? for more info.
Dear Sir i had tired the Method 2 , BUt it giving me the Invalid syntax Error can you pls tell me what should i do . I am using SQL server 2008 R2.
And i want to know how many features are installed in my SQL server 2008 R2???
Hi Rahul,
Thanks for bringing this up. There seems to be a typo in Line #3 of the script. Please remove the _(underscore) character that comes after Execquery and retry the script. Also as mentioned in the post, if you are using Sql 2008R2 then you need to change the namespace to computermanagement10 to get it to detect SQL 2008+ instances.
[Change Line #3 as shown below]
Set colItems = objWMIService.ExecQuery("SELECT * FROM SqlService",,48)
[Change namespace as shown below]
Set objWMIService = GetObject("winmgmts:\" & strComputer & "rootMicrosoftSqlServerComputerManagement10")
-Sudarshan
Thanks Very Much
This was a great, yet simple, little project. Very Helpful.
Do you also have a way to remove an instance programmatically?
I saw in one online forum the following line:
"C:Program FilesMicrosoft SQL Server100Setup BootstrapSQLServer2008R2setup.exe" /Action=Uninstall /INSTANCENAME=SQLEXPRESS /FEATURES=SQL,RS /QUIET
I am finding SQL Server 2008 R2 is particually difficult to remove from any computer!
Thank you in advance for any insight you have for this issues.
Is there any situation that the sql server is installed but the related service is not running at all? | https://blogs.msdn.microsoft.com/sqlserverfaq/2009/03/07/how-to-detect-sql-server-instances-features-installed-on-a-machine/ | CC-MAIN-2017-26 | refinedweb | 782 | 57.67 |
- NAME
- SYNOPSIS
- DESCRIPTION
- CAVEATS
- BUGS
- SEE ALSO
- AUTHOR
- DISCLAIMER OF WARRANTIES
NAME
MooX::Struct - make simple lightweight record-like structures that make sounds like cows
SYNOPSIS
use MooX::Struct Point => [ 'x', 'y' ], Point3D => [ -extends => ['Point'], 'z' ], ; my $origin = Point3D->new( x => 0, y => 0, z => 0 ); # or... my $origin = Point3D[ 0, 0, 0 ];
DESCRIPTION
MooX::Struct allows you to create cheap struct-like classes for your data using Moo.
While similar in spirit to MooseX::Struct and Class::Struct, MooX::Struct has a somewhat different usage pattern. Rather than providing you with a
struct keyword which can be used to define structs, you define all the structs as part of the
use statement. This means they happen at compile time.
A struct is just an "anonymous" Moo class. MooX::Struct creates this class for you, and installs a lexical alias for it in your namespace. Thus your module can create a "Point3D" struct, and some other module can too, and they won't interfere with each other. All struct classes inherit from MooX::Struct.
Arguments for MooX::Struct are key-value pairs, where keys are the struct names, and values are arrayrefs.
use MooX::Struct Person => [qw/ name address /], Company => [qw/ name address registration_number /];
The elements in the array are the attributes for the struct (which will be created as read-only attributes), however certain array elements are treated specially.
As per the example in the "SYNOPSIS",
-extendsintroduces a list of parent classes for the struct. If not specified, then classes inherit from MooX::Struct itself.
Structs can inherit from other structs, or from normal classes. If inheriting from another struct, then you must define both in the same
usestatement. Inheriting from a non-struct class is discouraged.
# Not like this. use MooX::Struct Point => [ 'x', 'y' ]; use MooX::Struct Point3D => [ -extends => ['Point'], 'z' ]; # Like this. use MooX::Struct Point => [ 'x', 'y' ], Point3D => [ -extends => ['Point'], 'z' ], ;
Similarly
-withconsumes a list of roles.
If an attribute name is followed by a coderef, this is installed as a method instead.
use MooX::Struct Person => [ qw( name age sex ), greet => sub { my $self = shift; CORE::say "Hello ", $self->name; }, ];
But if you're defining methods for your structs, then you've possibly missed the point of them.
If an attribute name is followed by an arrayref, these are used to set the options for the attribute. For example:
use MooX::Struct Person => [ name => [ is => 'ro', required => 1 ] ];
Using the
init_argoption would probably break stuff. Don't do that.
Attribute names may be "decorated" with prefix and postfix "sigils". The prefix sigils of
@and
%specify that the attribute isa arrayref or hashref respectively. (Blessed arrayrefs and hashrefs are accepted; as are objects which overload
@{}and
%{}.) The prefix sigil
$specifies that the attribute value must not be an unblessed arrayref or hashref. The prefix sigil
+indicates the attribute is a number, and provides a default value of 0, unless the attribute is required. The postfix sigil
!specifies that the attribute is required.
use MooX::Struct Person => [qw( $name! @children )]; Person->new(); # dies, name is required Person->new( # dies, children should be arrayref name => 'Bob', children => 2, );
Prior to the key-value list, some additional flags can be given. These begin with hyphens. The flag
-rw indicates that attributes should be read-write rather than read-only.
use MooX::Struct -rw, Person => [ qw( name age sex ), greet => sub { my $self = shift; CORE::say "Hello ", $self->name; }, ];
The
-retain flag can be used to indicate that MooX::Struct should not use namespace::clean to enforce lexicalness on your struct class aliases.
Flags
-trace and
-deparse may be of use debugging.
Instantiating Structs
There are two supported methods of instatiating structs. You can use a traditional class-like constructor with named parameters:
my $point = Point->new( x => 1, y => 2 );
Or you can use the abbreviated syntax with positional parameters:
my $point = Point[ 1, 2 ];
If you know about Moo and peek around in the source code for this module, then I'm sure you can figure out additional ways to instantiate them, but the above are the only supported two.
When inheritance or roles have been used, it might not always be clear what order the positional parameters come in (though see the documentation for the
FIELDS below), so the traditional class-like style may be preferred.
Methods
Structs are objects and thus have methods. You can define your own methods as described above. MooX::Struct's built-in methods will always obey the convention of being in ALL CAPS (except in the case of
_data_printer). By using lower-case letters to name your own methods, you can avoid naming collisions.
The following methods are currently defined. Additionally all the standard Perl (
isa,
can, etc) and Moo (
new,
does, etc) methods are available.
OBJECT_ID
Returns a unique identifier for the object.
FIELDS
Returns a list of fields associated with the object. For the
Point3Dstruct in the SYNPOSIS, this would be
'x', 'y', 'z'.
The order the fields are returned in is equal to the order they must be supplied for the positional constructor.
Attributes inherited from roles, or from non-struct base classes are not included in
FIELDS, and thus cannot be used in the positional constructor.
TYPE
Returns the type name of the struct, e.g.
'Point3D'.
TO_HASH
Returns a reference to an unblessed hash where the object's fields are the keys and the object's values are the hash values.
TO_ARRAY
Returns a reference to an unblessed array where the object's values are the array items, in the same order as listed by
FIELDS.
TO_STRING
Joins
TO_ARRAYwith whitespace. This is not necessarily a brilliant stringification, but easy enough to overload:
use MooX::Struct Point => [ qw( x y ), TO_STRING => sub { sprintf "(%d, %d)"), $_[0]->x, $_[0]->y; }, ] ;
CLONE
Creates a shallow clone of the object.
EXTEND
An exverimental feature.
Extend a class or object with additional attributes, methods, etc. This method takes almost all the same arguments as
use MooX::Struct, albeit with some slight differences.
use MooX::Struct Point => [qw/ +x +y /]; my $point = Point[2, 3]; $point->EXTEND(-rw, q/+z/); # extend an object $point->can('z'); # true my $new_class = Point->EXTEND('+z'); # extend a class my $point_3d = $new_class->new( x => 1, y => 2, z => 3 ); $point_3d->TYPE; # Point ! my $point_4d = $new_class->EXTEND(\"Point4D", '+t'); $point_4d->TYPE; # Point4D my $origin = Point[]->EXTEND(-with => [qw/ Math::Role::Origin /]);
This feature has been included mostly because it's easy to implement on top of the existing code for processing
use MooX::Struct. Some subsets of this functionality are sane, such as the ability to add traits to an object. Others (like the ability to add a new uninitialized, read-only attribute to an existing object) are less sensible.
BUILDARGS
Moo internal fu.
_data_printer
Automatic pretty printing with Data::Printer.
use Data::Printer; use MooX::Struct Point => [qw/ +x +y /]; my $origin = Point[]; p $origin;
With the exception of
FIELDS and
TYPE, any of these can be overridden using the standard way of specifying methods for structs.
Overloading
MooX::Struct overloads stringification and array dereferencing. Objects always evaluate to true in a boolean context. (Even if they stringify to the empty string.)
CAVEATS
Because you only get an alias for the struct class, you need to be careful with some idioms:
my $point = Point3D->new(x => 1, y => 2, z => 3); $point->isa("Point3D"); # false! $point->isa( Point3D ); # true my %args = (...); my $class = exists $args{z} ? "Point3D" : "Point"; # wrong! $class->new(%args); my $class = exists $args{z} ? Point3D : Point ; # right $class->new(%args);
BUGS
Please report any bugs to.
SEE ALSO
Moo, MooX::Struct::Util, MooseX::Struct, Class::Struct.
AUTHOR
Toby Inkster <[email protected]>.
This software is copyright (c) 2012. | https://metacpan.org/pod/MooX::Struct | CC-MAIN-2016-18 | refinedweb | 1,288 | 64.51 |
Source
python-clinic / Doc / library / tarfile.rst
:mod:`tarfile` --- Read and write tar archive files
Source code: :source:`Lib/tarfile.py`
The :mod:`tarfile` module makes it possible to read and write tar archives, including those using gzip, bz2 and lzma compression. Use the :mod:`zipfile` module to read or write :file:`.zip` files, or the higher-level functions in :ref:`shutil <archiving-operations>`.
Some facts and figures:
- reads and writes :mod:`gzip`, :mod:`bz2` and :mod:`lzma` compressed archives.
-.
Class for reading and writing tar archives. Do not use this class directly, better use :func:`tarfile.open` instead. See :ref:`tarfile-objects`.
The :mod:`tarfile` module defines the following exceptions:
Each of the following constants defines a tar archive format that the :mod:`tarfile` module is able to create. See section :ref:`tar-formats` for details.
The following variables are available on module level:
TarFile Objects
The :class: :class:`TarInfo` object, see :ref:`tarinfo-objects` for details.
A :class:`TarFile` object can be used as a context manager in a :keyword:`with` statement. It will automatically be closed when the block is completed. Please note that in the event of an exception an archive opened for writing will not be finalized; only the internally used file object will be closed. See the :ref:`tar-examples` section for a use case.
All following arguments are optional and can be accessed as instance attributes as well.
name is the pathname of the archive. It can be omitted if fileobj is given. In this case, the file object's :attr:'s mode. fileobj will be used from position 0.
Note
fileobj is not closed, when :class:`TarFile` is closed.
format controls the archive format. It must be one of the constants :const:`USTAR_FORMAT`, :const:`GNU_FORMAT` or :const:`PAX_FORMAT` that are defined at module level.
The tarinfo argument can be used to replace the default :class:`TarInfo` class with a different one.
If dereference is :const:`False`, add symbolic and hard links to the archive. If it is :const:`True`, add the content of the target files to the archive. This has no effect on systems that do not support symbolic links.
If ignore_zeros is :const:`False`, treat an empty block as the end of the archive. If it is :const: :meth:`TarFile.extract`. Nevertheless, they appear as error messages in the debug output, when debugging is enabled. If 1, all fatal errors are raised as :exc:`OSError` exceptions. If 2, all non-fatal errors are raised as :exc:`TarError` exceptions as well.
The encoding and errors arguments define the character encoding to be used for reading or writing the archive and how conversion errors are going to be handled. The default settings will work for most users. See section :ref:`tar-unicode` for in-depth information.
The pax_headers argument is an optional dictionary of strings which will be added as a pax global header if format is :const:`PAX_FORMAT`.
TarInfo Objects
A :class:`TarInfo` object represents one member in a :class:`TarFile`. Aside from storing all required attributes of a file (like file type, size, time, permissions, owner etc.), it provides some useful methods to determine its type. It does not contain the file's data itself.
:class:`TarInfo` objects are returned by :class:`TarFile`'s methods :meth:`getmember`, :meth:`getmembers` and :meth:`gettarinfo`.
Create a :class:`TarInfo` object.
A TarInfo object has the following public data attributes:
A :class:`TarInfo` object also provides some convenient query methods:
Examples
How to extract an entire tar archive to the current working directory:
import tarfile tar = tarfile.open("sample.tar.gz") tar.extractall() tar.close()
How to extract a subset of a tar archive with :meth: :keyword: :meth:`TarFile.add`:
import tarfile def reset(tarinfo): tarinfo.uid = tarinfo.gid = 0 tarinfo.uname = tarinfo.gname = "root" return tarinfo tar = tarfile.open("sample.tar.gz", "w:gz") tar.add("foo", filter=reset) tar.close()
Supported tar formats
There are three tar formats that can be created with the :mod:`tarfile` module:
The POSIX.1-1988 ustar format (:const:`USTAR_FORMAT`). It supports filenames up to a length of at best 256 characters and linknames up to 100 characters. The maximum file size is 8 GiB. This is an old and limited but widely supported format.
The GNU tar format (:const:`GNU_FORMAT`). It supports long filenames and linknames, files bigger than 8 GiB and sparse files. It is the de facto standard on GNU/Linux systems. :mod:`tarfile` fully supports the GNU tar extensions for long names, sparse file support is read-only.
The POSIX.1-2001 pax format (:const: ancient V7 format. This is the first tar format from Unix Seventh Edition, storing only regular files and directories. Names must not be longer than 100 characters, there is no user/group name information. Some archives have miscalculated header checksums in case of fields with non-ASCII characters.
- The SunOS tar extended format. This format is a variant of the POSIX.1-2001 pax format, but is not compatible.
Unicode issues :mod:`tarfile` are controlled by the encoding and errors keyword arguments of the :class:`TarFile` class.
encoding defines the character encoding to use for the metadata in the archive. The default value is :func: :ref:`codec-base-classes`. The default scheme is 'surrogateescape' which Python also uses for its file system calls, see :ref:`os-filenames`.
In case of :const:`PAX_FORMAT` archives, encoding is generally not needed because all the metadata is stored using UTF-8. encoding is only used in the rare cases when binary pax headers are decoded or when strings with surrogate characters are stored. | https://bitbucket.org/larry/python-clinic/src/eedbf20ed532/Doc/library/tarfile.rst | CC-MAIN-2015-14 | refinedweb | 931 | 59.7 |
.
RBList.SelectedIndexChange
then add a new function to handle the event:
protected void RBList_SelectedIndexChange
{
RadioButtonList RBList = sender as RadioButtonList;
...
}
You can then get the selected value from within this new function
i am using vs2005. I know where to add the eventhandler in vs2003.
where to add this vs2005???
Thanks....
RBList.SelectedIndexChange
is adding the event handler. Just add that line into GetRadioButtonList() after the line RBList.AutoPostBack = true;
Note that to work properly the GetRadioButtonList() function must be called every postback but I assume you're probably doing that anyway or your radiobuttonlist would disappear after you change the selectedindex.
First, set the Tag property of the RadioButtonList as, ie, "RBList"...
then:
object FindRBListValue(Control control)
{
foreach(Control child in control.Controls)
{
if (child.Tag is string)
if (string.Compare("RBList", child.Tag) == 0)
return (child as RadioButtonList ).Value;
object childs = FindRBListValue(child);
if (childs != NULL)
return childs;
}
return null;
}
Call this method like this:
...
object listValue = FindRBListValue(this);
if (listValue == NULL)
throw (new Exception("Could not found Radio Button List");
Try this, I'm not good at ASP.net, but should make the deal...
RadioButtonList rbl = (RadioButtonList) ap1.ContentContainer.FindC
but I'm guessing as he's set autopostback=true he wants to react to that event.
I just noticed the ID property of the RadioButtonList isn't being set though which is probably a good idea. | https://www.experts-exchange.com/questions/23803820/how-to-get-the-selected-item-value-of-RadioButtonList-which-is-inside-Accordion.html | CC-MAIN-2018-05 | refinedweb | 229 | 51.95 |
HTTP proxy for ClickHouse database
chproxy
Chproxy, is an http proxy and load balancer for ClickHouse database. It provides the following features:
- May proxy requests to multiple distinct
ClickHouseclusters depending on the input user. For instance, requests from
appserveruser may go to
stats-rawcluster, while requests from
reportserveruser may go to
stats-aggregatecluster.
- May map input users to per-cluster users. This prevents from exposing real usernames and passwords used in
ClickHouseclusters. Additionally this allows mapping multiple distinct input users to a single
ClickHouseuser.
- May accept incoming requests via HTTP and HTTPS.
- May limit HTTP and HTTPS access by IP/IP-mask lists.
- May limit per-user access by IP/IP-mask lists.
- May limit per-user query duration. Timed out or canceled queries are forcibly killed
via KILL QUERY.
- May limit per-user requests rate.
- May limit per-user number of concurrent requests.
- All the limits may be independently set for each input user and for each per-cluster user.
- May delay request execution until it fits per-user limits.
- Per-user response caching may be configured.
- Response caches have built-in protection against thundering herd problem aka
dogpile effect.
- Evenly spreads requests among replicas and nodes using
least loaded+
round robintechnique.
- Monitors node health and prevents from sending requests to unhealthy nodes.
- Supports automatic HTTPS certificate issuing and renewal via Let’s Encrypt.
- May proxy requests to each configured cluster via either HTTP or HTTPS.
- Prepends User-Agent request header with remote/local address and in/out usernames before proxying it to
ClickHouse, so this info may be queried from system.query_log.http_user_agent.
- Exposes various useful metrics in prometheus text format.
- Configuration may be updated without restart - just send
SIGHUPsignal to
chproxyprocess.
- Easy to manage and run - just pass config file path to a single
chproxybinary.
- Easy to configure:
server: http: listen_addr: ":9090" allowed_networks: ["127.0.0.0/24"] users: - name: "default" to_cluster: "default" to_user: "default" # by default each cluster has `default` user which can be overridden by section `users` clusters: - name: "default" nodes: ["127.0.0.1:8123"]
How to install
Precompiled binaries
Precompiled
chproxy binaries are available here.
Just download the latest stable binary, unpack and run it with the desired config:
./chproxy -config=/path/to/config.yml
Building from source
Chproxy is written in Go. The easiest way to install it from sources is:
go get -u github.com/Vertamedia/chproxy
If you don't have Go installed on your system - follow this guide.
Why it was created
ClickHouse may exceed max_execution_time and max_concurrent_queries limits due to various reasons:
max_execution_timemay be exceeded due to the current implementation deficiencies.
max_concurrent_queriesworks only on a per-node basis. There is no way to limit the number of concurrent queries on a cluster if queries are spread across cluster nodes.
Such "leaky" limits may lead to high resource usage on all the cluster nodes. After facing this problem we had to maintain two distinct http proxies in front of our
ClickHouse cluster - one for spreading
INSERTs among cluster nodes and another one for sending
SELECTs to a dedicated node where limits may be enforced somehow. This was fragile and inconvenient to manage, so
chproxy has been created :)
Use cases
Spread
INSERTs among cluster shards
Usually
INSERTs are sent from app servers located in a limited number of subnetworks.
INSERTs from other subnetworks must be denied.
All the
INSERTs may be routed to a distributed table on a single node. But this increases resource usage (CPU and network) on the node comparing to other nodes, since it must parse each row to be inserted and route it to the corresponding node (shard).
It would be better to spread
INSERTs among available shards and to route them directly to per-shard tables instead of distributed tables. The routing logic may be embedded either directly into applications generating
INSERTs or may be moved to a proxy. Proxy approach is better since it allows re-configuring
ClickHouse cluster without modification of application configs and without application downtime. Multiple identical proxies may be started on distinct servers for scalability and availability purposes.
The following minimal
chproxy config may be used for this use case:
server: http: listen_addr: ":9090" # Networks with application servers. allowed_networks: ["10.10.1.0/24"] users: - name: "insert" to_cluster: "stats-raw" to_user: "default" clusters: - name: "stats-raw" # Requests are spread in `round-robin` + `least-loaded` fashion among nodes. # Unreachable and unhealthy nodes are skipped. nodes: [ "10.10.10.1:8123", "10.10.10.2:8123", "10.10.10.3:8123", "10.10.10.4:8123" ]
Spread
SELECTs from reporting apps among cluster nodes
Reporting apps usually generate various customer reports from
SELECT query results.
The load generated by such
SELECTs on
ClickHouse cluster may vary depending
on the number of online customers and on the generated report types. It is obvious
that the load must be limited in order to prevent cluster overload.
All the
SELECTs may be routed to a distributed table on a single node. But this increases resource usage (RAM, CPU and network) on the node comparing to other nodes, since it must do final aggregation, sorting and filtering for the data obtained from cluster nodes (shards).
It would be better to create identical distributed tables on each shard and spread
SELECTs among all the available shards.
The following minimal
chproxy config may be used for this use case:
server: http: listen_addr: ":9090" # Networks with reporting servers. allowed_networks: ["10.10.2.0/24"] users: - name: "report" to_cluster: "stats-aggregate" to_user: "readonly" max_concurrent_queries: 6 max_execution_time: 1m clusters: - name: "stats-aggregate" nodes: [ "10.10.20.1:8123", "10.10.20.2:8123" ] users: - name: "readonly" password: "****"
Authorize users by passwords via HTTPS
Suppose you need to access
ClickHouse cluster from anywhere by username/password.
This may be used for building graphs from ClickHouse-grafana or tabix.
It is bad idea to transfer unencrypted password and data over untrusted networks.
So HTTPS must be used for accessing the cluster in such cases.
The following
chproxy config may be used for this use case:
server: https: listen_addr: ":443" autocert: cache_dir: "certs_dir" users: - name: "web" password: "****" to_cluster: "stats-raw" to_user: "web" max_concurrent_queries: 2 max_execution_time: 30s requests_per_minute: 10 deny_http: true # Allow `CORS` requests for `tabix`. allow_cors: true # Enable requests queueing - `chproxy` will queue up to `max_queue_size` # of incoming requests for up to `max_queue_time` until they stop exceeding # the current limits. # This allows gracefully handling request bursts when more than # `max_concurrent_queries` concurrent requests arrive. max_queue_size: 40 max_queue_time: 25s # Enable response caching. See cache config below. cache: "shortterm" clusters: - name: "stats-raw" nodes: [ "10.10.10.1:8123", "10.10.10.2:8123", "10.10.10.3:8123", "10.10.10.4:8123" ] users: - name: "web" password: "****" caches: - name: "shortterm" dir: "/path/to/cache/dir" max_size: 150Mb # Cached responses will expire in 130s. expire: 130s
All the above configs combined
All the above cases may be combined in a single
chproxy config:
server: http: listen_addr: ":9090" allowed_networks: ["10.10.1.0/24","10.10.2.0/24"] https: listen_addr: ":443" autocert: cache_dir: "certs_dir" users: - name: "insert" allowed_networks: ["10.10.1.0/24"] to_cluster: "stats-raw" to_user: "default" - name: "report" allowed_networks: ["10.10.2.0/24"] to_cluster: "stats-aggregate" to_user: "readonly" max_concurrent_queries: 6 max_execution_time: 1m - name: "web" password: "****" to_cluster: "stats-raw" to_user: "web" max_concurrent_queries: 2 max_execution_time: 30s requests_per_minute: 10 deny_http: true allow_cors: true max_queue_size: 40 max_queue_time: 25s cache: "shortterm" clusters: - name: "stats-aggregate" nodes: [ "10.10.20.1:8123", "10.10.20.2:8123" ] users: - name: "readonly" password: "****" - name: "stats-raw" nodes: [ "10.10.10.1:8123", "10.10.10.2:8123", "10.10.10.3:8123", "10.10.10.4:8123" ] users: - name: "default" - name: "web" password: "****" caches: - name: "shortterm" dir: "/path/to/cache/dir" max_size: 150Mb expire: 130s
Configuration
Server
Chproxy may accept requests over
HTTP and
HTTPS protocols. HTTPS must be configured with custom certificate or with automated Let's Encrypt certificates.
Access to
chproxy can be limitied by list of IPs or IP masks. This option can be applied to HTTP, HTTPS, metrics, user or cluster-user.
Users
There are two types of users:
in-users (in global section) and
out-users (in cluster section).
This means all requests will be matched to
in-users and if all checks are Ok - will be matched to
out-users
with overriding credentials.
Suppose we have one ClickHouse user
web with
read-only permissions and
max_concurrent_queries: 4 limit.
There are two distinct applications
reading from ClickHouse. We may create two distinct
in-users with
to_user: "web" and
max_concurrent_queries: 2 each in order to avoid situation when a single application exhausts all the 4-request limit on the
web user.
Requests to
chproxy must be authorized with credentials from user_config. Credentials can be passed via BasicAuth or via
user and
password query string args.
Limits for
in-users and
out-users are independent.
Clusters
Chproxy can be configured with multiple
clusters. Each
cluster must have a name and either a list of nodes
or a list of replicas with nodes. See cluster-config for details.
Requests to each cluster are balanced among replicas and nodes using
round-robin +
least-loaded approach.
The node priority is automatically decreased for a short interval if recent requests to it were unsuccessful.
This means that the
chproxy will choose the next least loaded healthy node among least loaded replica
for every new request.
Additionally each node is periodically checked for availability. Unavailable nodes are automatically excluded from the cluster until they become available again. This allows performing node maintenance without removing unavailable nodes from the cluster config.
Chproxy automatically kills queries exceeding
max_execution_time limit. By default
chproxy tries to kill such queries
under
default user. The user may be overriden with kill_query_user.
If
cluster's users section isn't specified, then
default user is used with no limits.
Caching
Chproxy may be configured to cache responses. It is possible to create multiple
cache-configs with various settings.
Response caching is enabled by assigning cache name to user. Multiple users may share the same cache.
Currently only
SELECT responses are cached.
Caching is disabled for request with
no_cache=1 in query string.
Optional cache namespace may be passed in query string as
cache_namespace=aaaa. This allows caching
distinct responses for the identical query under distinct cache namespaces. Additionally,
an instant cache flush may be built on top of cache namespaces - just switch to new namespace in order
to flush the cache.
Security
Chproxy removes all the query params from input requests (except the user's params and listed here)
before proxying them to
ClickHouse nodes. This prevents from unsafe overriding
of various
ClickHouse settings.
Be careful when configuring limits, allowed networks, passwords etc.
By default
chproxy tries detecting the most obvious configuration errors such as
allowed_networks: ["0.0.0.0/0"] or sending passwords via unencrypted HTTP.
Special option
hack_me_please: true may be used for disabling all the security-related checks during config validation (if you are feelying lucky :) ).
Example of full configuration:
# Whether to print debug logs. # # By default debug logs are disabled. log_debug: true # Whether to ignore security checks during config parsing. # # By default security checks are enabled. hack_me_please: true # Optional response cache configs. # # Multiple distinct caches with different settings may be configured. caches: # Cache name, which may be passed into `cache` option on the `user` level. # # Multiple users may share the same cache. - name: "longterm" # Path to directory where cached responses will be stored. dir: "/path/to/longterm/cachedir" # Maximum cache size. # `Kb`, `Mb`, `Gb` and `Tb` suffixes may be used. max_size: 100Gb # Expiration time for cached responses. expire: 1h # When multiple requests with identical query simultaneously hit `chproxy` # and there is no cached response for the query, then only a single # request will be proxied to clickhouse. Other requests will wait # for the cached response during this grace duration. # This is known as protection from `thundering herd` problem. # # By default `grace_time` is 5s. Negative value disables the protection # from `thundering herd` problem. grace_time: 20s - name: "shortterm" dir: "/path/to/shortterm/cachedir" max_size: 100Mb expire: 10s # Optional network lists, might be used as values for `allowed_networks`. network_groups: - name: "office" # Each item may contain either IP or IP subnet mask. networks: ["127.0.0.0/24", "10.10.0.1"] - name: "reporting-apps" networks: ["10.10.10.0/24"] # Optional lists of query params to send with each proxied request to ClickHouse. # These lists may be used for overriding ClickHouse settings on a per-user basis. param_groups: # Group name, which may be passed into `params` option on the `user` level. - name: "cron-job" # List of key-value params to send params: - key: "max_memory_usage" value: "40000000000" - key: "max_bytes_before_external_group_by" value: "20000000000" - name: "web" params: - key: "max_memory_usage" value: "5000000000" - key: "max_columns_to_read" value: "30" - key: "max_execution_time" value: "30" # Settings for `chproxy` input interfaces. server: # Configs for input http interface. # The interface works only if this section is present. http: # TCP address to listen to for http. # May be in the form IP:port . IP part is optional. listen_addr: ":9090" # List of allowed networks or network_groups. # Each item may contain IP address, IP subnet mask or a name # from `network_groups`. # By default requests are accepted from all the IPs. allowed_networks: ["office", "reporting-apps", "1.2.3.4"] # ReadTimeout is the maximum duration for proxy to reading the entire # request, including the body. # Default value is 1m read_timeout: 5m # WriteTimeout is the maximum duration for proxy before timing out writes of the response. # Default is largest MaxExecutionTime + MaxQueueTime value from Users or Clusters write_timeout: 10m # IdleTimeout is the maximum amount of time for proxy to wait for the next request. # Default is 10m idle_timeout: 20m # Configs for input https interface. # The interface works only if this section is present. https: # TCP address to listen to for https. listen_addr: ":443" # Paths to TLS cert and key files. # cert_file: "cert_file" # key_file: "key_file" # Letsencrypt config. # Certificates are automatically issued and renewed if this section # is present. # There is no need in cert_file and key_file if this section is present. # Autocert requires application to listen on :80 port for certificate generation autocert: # Path to the directory where autocert certs are cached. cache_dir: "certs_dir" # The list of host names proxy is allowed to respond to. # See allowed_hosts: ["example.com"] # Metrics in prometheus format are exposed on the `/metrics` path. # Access to `/metrics` endpoint may be restricted in this section. # By default access to `/metrics` is unrestricted. metrics: allowed_networks: ["office"] # Configs for input users. users: # Name and password are used to authorize access via BasicAuth or # via `user`/`password` query params. # Password is optional. By default empty password is used. - name: "web" password: "****" # Requests from the user are routed to this cluster. to_cluster: "first cluster" # Input user is substituted by the given output user from `to_cluster` # before proxying the request. to_user: "web" # Whether to deny input requests over HTTP. deny_http: true # Whether to allow `CORS` requests like `tabix` does. # By default `CORS` requests are denied for security reasons. allow_cors: true # Requests per minute limit for the given input user. # # By default there is no per-minute limit. requests_per_minute: 4 # Response cache config name to use. # # By default responses aren't cached. cache: "longterm" # An optional group of params to send to ClickHouse with each proxied request. # These params may be set in param_groups block. # # By default no additional params are sent to ClickHouse. params: "web" # The maximum number of requests that may wait for their chance # to be executed because they cannot run now due to the current limits. # # This option may be useful for handling request bursts from `tabix` # or `clickhouse-grafana`. # # By default all the requests are immediately executed without # waiting in the queue. max_queue_size: 100 # The maximum duration the queued requests may wait for their chance # to be executed. # This option makes sense only if max_queue_size is set. # By default requests wait for up to 10 seconds in the queue. max_queue_time: 35s - name: "default" to_cluster: "second cluster" to_user: "default" allowed_networks: ["office", "1.2.3.0/24"] # The maximum number of concurrently running queries for the user. # # By default there is no limit on the number of concurrently # running queries. max_concurrent_queries: 4 # The maximum query duration for the user. # Timed out queries are forcibly killed via `KILL QUERY`. # # By default there is no limit on the query duration. max_execution_time: 1m # Whether to deny input requests over HTTPS. deny_https: true # Configs for ClickHouse clusters. clusters: # The cluster name is used in `to_cluster`. - name: "first cluster" # Protocol to use for communicating with cluster nodes. # Currently supported values are `http` or `https`. # By default `http` is used. scheme: "http" # Cluster node addresses. # Requests are evenly distributed among them. nodes: ["127.0.0.1:8123", "shard2:8123"] # Each cluster node is checked for availability using this interval. # By default each node is checked for every 5 seconds. heartbeat_interval: 1m # Timed out queries are killed using this user. # By default `default` user is used. kill_query_user: name: "default" password: "***" # Configuration for cluster users. users: # The user name is used in `to_user`. - name: "web" password: "password" max_concurrent_queries: 4 max_execution_time: 1m - name: "second cluster" scheme: "https" # The cluster may contain multiple replicas instead of flat nodes. # # Chproxy selects the least loaded node among the least loaded replicas. replicas: - name: "replica1" nodes: ["127.0.1.1:8443", "127.0.1.2:8443"] - name: "replica2" nodes: ["127.0.2.1:8443", "127.0.2.2:8443"] users: - name: "default" max_concurrent_queries: 4 max_execution_time: 1m - name: "web" max_concurrent_queries: 4 max_execution_time: 10s requests_per_minute: 10 max_queue_size: 50 max_queue_time: 70s allowed_networks: ["office"]
Full specification is located here
Metrics
Metrics are exposed in prometheus text format at
/metrics path. | https://golangexample.com/http-proxy-for-clickhouse-database/ | CC-MAIN-2020-05 | refinedweb | 2,913 | 58.38 |
Python Pass
In this section, you will learn Python
pass statement.
Python
pass Statement
pass is actually a
null statement which is generally used as a placeholder. When you want to declare a function or a loop but not want to provide the implementation then you can use
pass statement. It is similar to
; in C programming language or
nop in assembly language.
The
pass statement will result in no operation (NOP) which means nothing happens when
pass is executed.
So what is the difference between
pass and Python comments when nothing happens to both of them?
The comments are ignored and not executed, but
pass statement will be executed resulting in nothing.
The following is the syntax of
pass in Python:
pass
If you want to provide the implementation of a loop or function in future then you have to use
pass statement because a function or a loop can never have an empty body in Python.
pass statement creates an empty body for you.
pass Statement Example:
l = ['p', 'y', 't', 'h', 'o', 'n'] for i in l: pass
So here,
for loop has an empty body indicated by
pass statement. If there is no
pass statement and body of
for is left empty you will have a
SyntaxError - expected an indented block.
Similarly,
pass can also be used in classes and functions when you plan to implement classes and function in the future. Consider the example below:
def function(args): pass
class ABC: pass | https://www.delftstack.com/tutorial/python-3-basic-tutorial/python-pass/ | CC-MAIN-2018-43 | refinedweb | 247 | 69.21 |
Using Live Visual Tree and Live Property Explorer to customize the Media Player (XAML, C#)
In this series of tutorials on how to customize your
MediaPlayer, we have seen how to customize a button in part I. Now we will see how we can use Live Visual Tree and Live Property to make our lives easier when we are trying to design our
MediaPlayer element.
All of the code can be found on Github here
Before we had no way to edit elements on the fly, we had to imagine what would happen when we changed a property like
Margin,
Height,
Color,
BrushThickness etc. Web developers have tons of tools like Firebug for Firefox, Chrome Tools for Chrome and Developer Tools for Edge and IE that allow them to do this, so why not us? The developing gods (Microsoft in our case) have answered our call and have given us the Live Visual Tree and Live Property Explorer tools which address exactly these issues. I will talk about these two elements and how they can help us develop better and faster.
In this tutorial we will implement and design a custom control that will be shown when the video has finished playing. The user will be able to rate the video using this control and we will also move the
PlayPauseButton to the bottom left using Live Visual Tree and Live Property Explorer.
This tutorial will cover:
- What the Live Visual Tree and Live Property Explorer components are, how to use them, and why they are great tools
- How to use these tools to speed up your development
- How to add a control to the
MediaPlayerthat users can interact with
- How to move an element in the
MediaPlayercontrol
The final version of our player will have:
- A custom element in which users can rate the video. This element will have three different buttons (like, neutral, dislike), which will be shown at the end of the video.
- These three buttons will have different actions (rate the video).
- A
PlayPauseButtonthat have been moved and re-sized.
or in other words:
Let’s get started, I will assume that you have:
- Windows OS ;)
- Visual Studio 2015 (here) installed
- Media Player Framework vsix installed.
- Setting (downloading and referencing) a theme to the MediaPlayer, in this example I will be using Entertainment.xaml template theme.
Live Visual Tree and Live Property Explorer
This new tool will speed up your development as you no longer not need to reload the application every time you change something, thanks to Live Property Explorer. You can find Live Visual Tree under: DEBUG -> WINDOWS -> Live Visual Tree and Live property Explorer under the same path.
Like you can see here:
Live Visual Tree on the right and the Live Property Explorer on the left:
You can see that Live Visual Tree provides information about the number of XAML elements inside each container (here we can see that we have a
Grid, a
StackPanel and more). Live Visual Tree will show only visible elements, and when an element changes from one state to another you can see that Live Visual Tree is changing at runtime which is very helpful (and AWESOME).
Live Property Explorer shows default values for properties, values which were inherited from other controls and the local values of control properties. You can modify local values, here for example we could choose to change the
StackPanel
HorizontalAlignment=center to
Left and we could change
VerticalAlignment="Top" to
Bottom and the effects would be taken into account without having to reload the app.
As you can see here:
Live Visual Tree and Live Property Explorer are two great tools that will help you speed up your development time since you will no longer need to recompile your application every time you wish to try a new design or version of a design.
(In this part I will not go over how to copy the theme template into the player, for more information on this please read part I).
First we will create a Windows 10 application with the
MvvmLight Framework:
If you don’t have MvvmLight, I can only highly recommend it to you download here.
Now that we have created a Windows 10 application, we will need to create the custom control, for this example I will create a folder called
Contrls and add a
UserControl called
RateMyVideoControl. (We deliberately do not name the folder
Controls, to avoid namespace clashes).
Now we create a
Grid element with 3 columns in which we will have 3 images: up vote, neutral vote and down vote. These 3 buttons will be linked to a
Command property which will show a different message to the user depending on which button is clicked.
Here is the code for the
UserControl :
<StackPanel> <TextBlock FontSize="32" Margin="10" Text="Did you like this video?"/> <Grid Height="70"> <Grid.ColumnDefinitions> <ColumnDefinition Width="0.3*" /> <ColumnDefinition Width="0.3*" /> <ColumnDefinition Width="0.3*" /> </Grid.ColumnDefinitions> <Button Grid. <Image Source="/Assets/up.png"></Image> </Button> <Button Grid. <Image Source="/Assets/Neutral.png"></Image> </Button> <Button Grid. <Image Source="/Assets/down.png"></Image> </Button> </Grid> </StackPanel>
Next we add these
RelayCommands to our
MainViewModel file so that the binding can happen:
public RelayCommand UpVoteCommand { get { return new RelayCommand(async () => { var dialog = ServiceLocator.Current.GetInstance<IDialogService>(); await dialog.ShowMessage("Custom Player", "Up Voted."); //TODO: add more logic here }); } } public RelayCommand NeutralVoteCommand { get { return new RelayCommand(async () => { var dialog = ServiceLocator.Current.GetInstance<IDialogService>(); await dialog.ShowMessage("Custom Player", "Neutral Voted."); //TODO: add more logic here }); } } public RelayCommand DownVoteCommand { get { return new RelayCommand(async () => { var dialog = ServiceLocator.Current.GetInstance<IDialogService>(); await dialog.ShowMessage("Custom Player", "Down Voted."); //TODO: add more logic here }); } }
In your IDE you should have a control that looks like this:
Now using Live Visual Tree we will look into the
MediaPlayer to see where we can place this component so that the user can see it once the video has ended.
We can see that in the
InteractivityContainer element we have a
Border element that holds all of the controls for the player. This looks like a good place to set our own control. We will then insert our control and will also add a binding to the
Visibility property so that we can show and hide our control using a boolean.
So looking with Live Visual Tree we now will have:
Our XAML Code in the
MediaPlayer:
<contrls:RateMyVideoControl
C# code for the
IsRateMyVideoVisible property:
private bool _isRateMyVideoVisible = false; public bool IsRateMyVideoVisible { get { return _isRateMyVideoVisible; } set { Set(ref _isRateMyVideoVisible, value); } }
And lastly in our
MediaEnded event on the
MediaPlayer. This will tell us when to show the control to the user so that we only show it when the user has finished watching the video.
public MainViewModel Vm => (MainViewModel)DataContext; public MainPage() { InitializeComponent(); Loaded += (s, e) => { //When player is ending show the Control player.MediaEnded += Player_MediaEnded; }; } private void Player_MediaEnded(object sender, Microsoft.PlayerFramework.MediaPlayerActionEventArgs e) { Vm.IsRateMyVideoVisible = true; }
When the video has finished playing we now have this:
which is not great… On we go to fix this issue!
Moving elements using Live Visual Tree and Live Property Explorer
As we saw previously we have a custom control that is shown when the video has ended, however, our play/pause button is hiding it!
Again using Live Visual Tree we have:
From what we see here we are going to need to search in our player theme for the element named
PlayPauseButton. We'll take a copy of it and then comment it out (just in case we want to go back again), and then paste the copy into the element called
TimelineContainer.
So in our
PlayerTheme.xaml resource file, around the
Grid named
TimelineContainer we will now have:
<Grid x: <AppBarButton x: <local:MediaControls.Behavior> <local:PlayPauseButtonBehavior </local:MediaControls.Behavior> </AppBarButton> <Grid Margin="30,4,30,7"> The rest of the code.....
Your player should look like this ugly thing now, it’s normal:
Again using Live Visual Tree and looking for the
PlayPauseButton, we can see that it has a
Height and
Width of 140. We are going to change its
Height and
Width properties using the Live Property Explorer. You can change the properties
Height and
Width to 40px and all the sudden it looks a bit better, and if we add more left margin 90px to the
Grid which had a left margin of only 30px to start with, we are even better =).
Once we have modified these properties, our player should look as follows:
And there you have it, you have customized your
MediaPlayer again and seen how Live Visual Tree and Live Property Explorer can allow you to gain a lot of time when you are trying to position different elements in your app!
Happy Coding =).
All of the code can be found on Github here
Originally published at engineering.dailymotion.com on December 14, 2015. | https://medium.com/dailymotion/using-live-visual-tree-and-live-property-explorer-to-customize-the-media-player-xaml-c-c1f5bb6cf73e?source=collection_home---4------20--------------------- | CC-MAIN-2019-18 | refinedweb | 1,484 | 50.36 |
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- where should I put log files?
- Editing a page in VS 2005 - add a control and it's not in the code behind.
- VS8 bug? something corrupted my Default.aspx
- Best Codeplex sample for showing best coding practices?
- Need help with Repeater data binding question...
- Bug? Strange between Wizard control and client javascript code
- Preventing IIS logging webresource.axd requests
- Change the master GridView after detail change?
- Change the master GridView after detail change?
- Active directory error on windows server 2003
- DataView Error on Update With DropDownList
- precompiled exception
- Web.Config warnings in VS2005
- Databinding programmatically
- whats wrong with this XML, used xmlwriterclass
- Build Solution after Modifying Web.Config
- Please help me to solve this
- Asp.Net 2.0 Net.Mail. I don't know what else to try. Thanks.
- ASP.NET Cache vs Window System Cache
- ASP:Repeater horizontal 3 column?
- Handling Post Request
- Publish one page only
- Disallow space using regular expression validator
- Client -Server in Windows Applns...
- AD Datasource for DropDown box
- Dumb Gridview Question
- Dynamic Validator Help Please
- .Net 2.0 : How to use transaction in a WS ?
- asp.net tag with a hash
- Mix of javascript, image and href
- Sending email with ASP.NET 2.0
- Gridview,CheckboxList and ObjectDataSource
- Problems debugging script in aspx pages (vs2005)
- SET DATEFIRST and ASP.NET
- Can't add to placeholder
- Impersonation and Delegation with ASP.NET 2.0 on 2 Servers
- Gridview CheckBoxField
- Static Classes in Web Applications
- DropDownList
- The remote host closed the connection. The error code is 0x80072746.
- Protect / Authorize urls.
- RequiredFieldValidator switching on and off AND TextChanged events not firing
- img src="~/"
- setting a usercontrol property as another control
- How is everyone else doing IE7 testing?
- Crystal Report Assembly problem
- Asp.Net 2.0 Wizard control and SessionId
- Does it matter if one of my classes is very big?
- VB.NET Question - Static, Shared, Confused
- How to disable/enable cache between dev and production environment
- posting radiobuttons inside a gridview do not persist selection after postback..
- find - control
- asp:Image inside editable DetailsView
- Embedded ASP.Net Page or User Control
- get ${APPDATA} for log files
- Page comes up blank
- Validation Controls in FormView
- Parser Error Message: Unknown server tag
- How do I preview a posted file?
- xml spreadsheet question
- RFV. Problem with ID. I think ...
- DefaultCredentials blank
- web parts & anonymous users
- Application design...
- Anyway to tell when something was compiled?
- Why does ASP.NET release cache items before the expiration time?
- <Invalid Application Pool> under IIS website - properties dialog b
- Set Start URL with project Start Page (Visual Studio)
- Position sql data source to the combo selected value in asp.net 2. ?
- file system -based website vs query string based website
- why radio buttons showing value
- anonymousIdentification setting fails to override root configurati
- OnCommand Problem with Linkbutton as a TemplateItem
- Is the Microsoft.NET Framework required for web applications?
- Setting a textbox in a GridView to ReadOnly?
- Equivalent of Application.ProductVersion
- DetailsView and DataKeys
- Question
- Minimum Permissions Required to Run ASP.NET
- q; Server.Transfer problem
- Redirect after interval
- How do I get security login info from a database? ASP.NET
- Crystal Reports -- how to create HTML-like tables?
- Parser Error Message: Could not load type...
- 64bit builds
- The type or namespace name could not be found
- Very Urgent - Please suggest me a solution
- Browser is shut down after download!?
- Crystal is not installed on production server.
- DataFormatString Help Please
- Extra Backslash After LoadXML
- login controls don't find database, since I'm not using sqlexpress
- Length of digit after decimal point
- How to load page in browser
- relative App_Themes path
- Menu Control - controlling style
- Object reference not set to an instance of an object.
- StringWriter object and dispose method
- need some help
- Basic ASP.NET regarding query string and results
- Global datasets
- Dynamic SQLDataSource with Gridview - Update Parameters
- ATLAS / AJAX newsgroup?
- Referencing Connection Strings in web.config Problems
- Importing an assembly?
- Where to place server code to invoke when client page closes.
- Enterprise Library Data Block
- Asp.net application and Memory of the server
- Async web services / asp.net 2.0 web parts / Ajax
- server.createobject differences between c# and vb.net
- Requirement for freshers in CTS
- Problem deploying ASP.NET 2.0 application. Access denied and so on
- DataGrid
- which linkbutton clicked
- html at end of download - urgent please help!!
- Making 10 POST requests from ASP.NET asynchronously
- ASP.NET Exception Handling
- sharing states across multiple sites within a server
- Authentication Cookie not in Request.Cookies
- Creating bandwidth usage app?
- aspnet_compile - debug or release?
- Button Click
- aspnet_compiler
- aspnet_compiler 3 questions
- Who knows where to find the car rental in Moscow?
- Can't display file in Browser. Need help please! Thank you.
- GridView and parsing
- ASP.NET SMTP mail never received
- Role based menu
- Help!! Dynamic Textbox, validation requiredFieldValidator
- Embed resource
- DataTable columns collection
- (Repost) Anyone used AspDotNetStorefront
- Showing a different .aspx page in each View of a MultiView control
- Immediate window gone in VS2005?
- Connecting to a database remotely through VS2005
- Plain text and html not getting along in net.mail.message
- gridview and sqldatasource - refresh the gridview
- Urgent- Please help me
- AJAX control in Master pages
- user control inside gridview
- Connection information in Data Layer
- running a .net web app on a vax machine
- SetFocus convert from 2003 to 2005 problem
- Possible to access data source not on local server?
- beginner question about ASP.Net from VStudio 2005.
- Getting the server-adjusted ID of a repeated user control
- Please help adding columns to the existing Dataset table
- asp.net pluggable pages
- ASP.NET v2.0 and Repeater controls
- Who fires the postback?
- multiple runtimes on a Win2000 server and IIS 5
- Unwanted data injected into datagrid textbox
- Caching file stream?
- Groove server 2007 installation on windows 2003 server x64
- Memory Usage ASP.NET (Win2000)
- IIS ignores web.config in subfolder
- ASP.Net Site or Sharepoint Portal...
- Is SQL server not installed with VS2005
- Hi!
- Double postback
- Class Access Restriction
- Problem deploying ASP.Net 2.0 application
- Replacing character with ASCII code (HTML)
- Databind to Accordion Control
- "Local Internet Zone"
- trouble with trimmed sitemap
- Web TextBox TextChanged Event
- DATAGRID SETTING VISIBILITY of CONTROLS on RUN TIME.
- Integrated Windows Authentication for Multiple Domains
- Can't debug since I installed IE7
- Skins and CSS in ASP.NET 2.0. I am completely confused!
- html table
- Setting UserControls properties in .ascx file
- tracking website users!
- Problem with event handler
- [asp] remembering values after postback - changes values
- HttpWebRequest Asynchronous
- gridview template function not called
- Properties window is not shown
- ienumerable, arraylist and datatable
- getelementbyid cant find runtime id
- UserControl with collections
- Visual Studio and Vista
- HttpWebRequest BeginGetRequestStream question
- triggering SQLDATASOURCE insert or update command programatically?
- asp.net transactions
- Gridview encoding, or how to run commands before gridview's default databinding, or, how do I disable default databinding at all?
- Stopping Formview insert command button - too late to trigger isvalid=false ??? viewstate lost after update
- Retrieve a Value from the DataGrid Control
- Getting to the bottom of naturism ...
- VS 2005 style attribute
- Sharing Web Application (really expert level question)
- q; solution with asp.net and asp projects.
- how to give the focus to a given page
- GetHtmlErrorMessage()
- Reason: Not associated with a trusted SQL Server connection.
- datagrid - two rows
- CSS Combobox
- CSS for form labels and input boxes
- Treeview right to left display?
- GridView events
- Generate zip files on the fly and send it directly to the browser (with ICSharpZipLib)
- Visual Studio 2005 viewing Refrences
- update to VS 2003 SP1 and 'Wireless LAN Connection Indicator"
- What is Postback?
- Integrated Security=true
- simple ajax drop down list
- How can I remove Black Arrows from horizontal menu?
- datetime popup in asp.net 2.0
- Nested user controls and performance implications
- nesting repeaters
- objectdatasource sqldatareader and conection pooling
- disabling button in CreateUserWizzard - problem
- Looping through a formview web control .. childtable?
- FTP w/ VS 2005
- Urgent please
- validation summary control issue
- Web services and XML
- disabling button in CreateUserWizzard - problem
- [IE: Yes Opera:Yes Mozilla:No] : Error on Postback and Validation
- simple question - url target | https://bytes.com/sitemap/f-329-p-43.html | CC-MAIN-2018-30 | refinedweb | 3,262 | 50.23 |
Investors eyeing a purchase of Owens Corning (Symbol: OC) stock, but tentative about paying the going market price of $41.16/share, might benefit from considering selling puts among the alternative strategies at their disposal. One interesting put contract in particular, is the May 2016 put at the $35 strike, which has a bid at the time of this writing of $2.05. Collecting that bid as the premium represents a 5.9% return against the $35 commitment, or a 9.1% annualized rate of return (at Stock Options Channel we call this the YieldBoost ).
Selling a put does not give an investor access to OC Owens Corning sees its shares decline 14.7% and the contract is exercised (resulting in a cost basis of $32.95 per share before broker commissions, subtracting the $2.05 from $35), the only upside to the put seller is from collecting that premium for the 9.1% annualized rate of return.
Worth considering, is that the annualized 9.1% figure actually exceeds the 1.7% annualized dividend paid by Owens Corning by 7.4%, based on the current share price of $41.16. And yet, if an investor was to buy the stock at the going market price in order to collect the dividend, there is greater downside because the stock would have to fall 14.74% to reach the $35 strike price.
Always important when discussing dividends is the fact that,.7% annualized dividend yield.
Below is a chart showing the trailing twelve month trading history for Owens Corning, and highlighting in green where the $35 strike is located relative to that history:
The chart above, and the stock's historical volatility, can be a helpful guide in combination with fundamental analysis to judge whether selling the May 2016 put at the $35 strike for the 9.1% annualized rate of return represents good reward for the risks. We calculate the trailing twelve month volatility for Owens Corning (considering the last 252 trading day closing values as well as today's price of $41.16) to be 29%. For other put options contract ideas at the various different available expirations, visit the OC Stock Options page of StockOptionsChannel.com.
In mid-afternoon trading on Tuesday, the put volume among S&P 500 components was 649,331 contracts, with call volume at 733,198,. | https://www.nasdaq.com/articles/commit-purchase-owens-corning-35-earn-91-annualized-using-options-2015-09-29 | CC-MAIN-2020-40 | refinedweb | 391 | 65.01 |
grade.pygrade.py
grade.py is a testing framework that aids in grading python assignments. grade.py gracefully handles exceptions and offers error carried forward support.
This package differs from standard testing frameworks in two major ways. First, it relies on a correct implementation of the module, making test scripts quick to write and enabling error carried forward. Second, it is designed to identify graded quality of performance, rather than giving binary PASS/FAIL judgements.
UsageUsage
As an end user (i.e. a grader), usage is simple:
$ grade.py path/to/student/module.py
For example, one could test all the python modules in a directory of student submissions with the command:
grade.py students/*/*.py. Of course, this will only work if testing scripts have been appropriately registered by the lead grader.
Writing test scriptsWriting test scripts
Writing a test script comes in two phases:
- Correctly implement the assigned module specification.
- Write a test suite with functions that generate output using the module.
Example test functionExample test function
def test_foo(module): for i in range(10): yield Check('foo({i})', note='good effort')
This function might generate the following output:
foo(0) should be 0, but student code raised an exception: File "flc37/foo.py", line 15, in foo return 1.0 / x ZeroDivisionError: integer division or modulo by zero Note: good effort foo(5) should be 5, but it is 5.0 Note: good effort
You can find a more complete example in
example/, which includes two "student submisions" along with an example grading package and detailed commentary.
To create a new test, first copy the boilerplate from
test/grade_template/. A package in the
tests/ directory that follows the naming convention
grade_MODULE/ will be used to grade any module with the name
MODULE. Putting the module in this directory makes it visible to the grade.py command line tool.
Distributing test scriptsDistributing test scripts
We are still in the process of developing a generalized distribution strategy. At present, the best option is fork this repository and add scripts directly into the repository. Then update the name of the package and upload it to PyPI so that graders can easily download and update the package using e.g.
$ pip install cs1110grading | https://libraries.io/pypi/cs1110grade | CC-MAIN-2022-21 | refinedweb | 372 | 56.25 |
Everyone more lies. Not because it's wrong, mind you -- but because it's old and refers to ancient development environments which no one uses anymore. Pascal with MPW? Uh... CodeWarrior? VS 6? Yeah, like I said, it's out-dated, to be sure. Hopefully that issue will be addressed in a future release as well (but I can assure you it won't be addressed in the next release, unfortunately).
As a way to sort of formalize the process of writing a new plugin, I'm going to write a blog posting about how to write a plugin using Visual Studio 2005. You can think of this as sort of a precursor to actual documentation. This will help me to solidify my thoughts, as well as find out what areas still confuse people (which tends to make for more robust documentation in the long run). If everything goes well, then I may cover gcc or even XCode. We'll see though; one fish at a time, so to speak.
Before we can really begin with the whole "setup" topic, you need to have a bit of background information about how plugins work in REALbasic. You don't need to know much of anything about the SDK itself to follow along, so for beginners, this is a good starting point.
Every REALbasic plugin ever made is nothing more than a fancy shared library. So on Windows, you make a DLL, on the Mac it's some weird .dylib (I think), and on Linux it's a .so file. The .rbx file format is what you ultimately want to get your plugin into, but that's just a virtual volume that can be created with the anciently-named "Plugin Converter" project that comes with the SDK. The virtual volume just houses the plugin "parts" (the shared libraries) in such a way that the REALbasic IDE can grok them.
Note that the IDE will *only* load a plugin for its architecture. So if you are running a Windows IDE, it will only load up the DLL plugin part for Windows. If you want your plugin to be usable on any platform, you must make shared library for it (even if the shared library does nothing more than expose your plugin's API to REALbasic). More on this later, though.
All plugins begin their life in a function called REALPluginMain (or simply "main", depending on the platform). When the IDE or application loads a plugin, this is the entrypoint. Thankfully, you don't need to care about it too much because this entrypoint will be in every single plugin using the SDK -- it's defined for you in PluginMain.cpp. This entrypoint does a bunch of setup, some housekeeping, etc and it eventually calls the part *you* need to care about: PluginEntry.
The PluginEntry function is where all of your "registration" code will go. It is the place where you tell the loader "I have a class named Foo, and it has these code items in it." -- your plugin's API.
This registration code it what tells the IDE what classes, modules, and other pieces of code exist so that things like autocomplete and the compiler will work. The user will use your plugin in the IDE to design their application, and when they hit Build (or Run), your plugin is wrapped up into the final executable -- but not your entire plugin. Only the plugin part that is needed for the executable (why would a Windows .exe file need a Linux .so plugin part, after all?).
When the user launches that executable, your plugin is loaded up just like it was with the IDE, and the same registration code is called. This registration code also tells the framework "hey, when you need this functionality, it lives right here."
Ok, that's enough background about how plugins work at a high level. Now we can talk about how to make a very, very basic plugin using Visual Studio 2005. We're going to make this plugin from scratch, but it assumes you have the latest version of the plugins SDK. I am using Visual Studio Team Suite, but the steps should be the same for all but possibly the Express version (I've not used that version, but I hear it has some differences from the non-free siblings).
First, go to File->New->Project. and select Visual C++, Win32 Project and give the project whatever name is appropriate for you (mine is called simply, REALbasic Plugin). This will bring up the project creation wizard. You want to select DLL as the project type, and click the Empty Project checkbox. Click the Finish button, and you will have the skeleton empty DLL project.
Now we are going to add in the files you need for the SDK. At this point, I usually copy the plugin SDK into my project's directory (I do this so I can ensure that grabbing a new SDK will never affect older projects unless I want it to). The only code you need to copy over resides in the Glue Code and Includes directories of the SDK. Once you have the SDK code next to the project, you need to add some of the SDK files directly to the project.
We are going to add PluginMain.cpp to the Source Files folder -- this is the guts of the SDK functionality which provides the implementation details. Then we are going to add the rb_plugin.h, REALplugin.h and WinHeader++.h files to the Header Files folder. This is the declaration guts of the SDK. Now we've got the SDK included into the project!
The next step is to configure the project settings so that it matches our needs. To do this, you go up to Project->Properties, and into the Configuration tree. Our first stop is the C/C++ section, under the General item. We need to add some additional include directories for the header files we included (since VS is a little pedantic about header files and includes, which is a good thing). We want to add the SDK's includes directory, relative to the project itself. This is what my configuration looks like (note, I also turned off 64-bit porting issues because I don't care about them):
The next step is to change some preprocessor settings. Since most plugins don't use QuickTime on Windows (and the ones that do should highly reconsider, in my not-so-humble opinion!), you want to set IGNOREQT as one of the preprocessor settings. You must do this in order for the SDK to entirely ignore QuickTime. Forgetting to do this will yield some very cryptic errors dealing with the QT namespace and movies.
The last required step is to include WinHeader++.h in all of our files. We can do this from the Advanced tab, under the Force Includes field. You have to have WinHeader++.h included before any of the other include files in any source file in order for the project to function properly since it defines some of the very basic types used by the SDK.
The final steps that I usually take (but it is technically optional) is to statically link in the C runtime library instead of using a dynamic version of it. I do this so that older versions of Windows can still use my plugin without needing the newer runtime. You do this in the Code Generation pane by changing Multi-threaded Debug DLL to Multi-threaded Debug. I also disable exceptions and run time type info (which is in the Language pane).
Now we're ready for the "meat" of your own plugin. Go up to Project->Add->New Item and add a new C++ source code file (I named my Main.cpp). This file should look like this:
#include "rb_plugin.h"
void PluginEntry( void )
{
}
If you hit Build at this point, you will have successfully built a REALbasic plugin for Windows using Visual Studio 2005.
As you can see, it wasn't nearly as hard and scary as you might have imagined. And sometimes, starting off from one of the example projects doesn't really teach you anything because it's easy to miss the setup steps. It's also easy to not understand why you have to do the setup steps.
One final note is that there would be a template for a REALbasic plugin, but Microsoft has crippled Visual Studio 2005 for no good reason. It is impossible to make any templates for C++ projects at all (it's only supported for the .NET projects). Thank you so much Microsoft. :: sighs :: The good news is that you can easily copy what we've created today and save it off as your own "template" of sorts. It's nothing more than a blank plugin project, so it can be used for any of the plugins you want to write.
So -- how did I do? Did I leave you wondering "but how do I set up this?"
Excellent walkthrough, thanks.
I might even start playing with plugins now
I'm glad you found it useful. If you can find any area where you're confused, please let me know.
It might be worth mentioning that in order to build unmanaged code (and therefore DLLs) with VC++ 2005 Express Edition, it's necessary to download the Microsoft Platform SDK
See for details
That's good to know -- I've never even seen the Express Edition before, so I wasn't sure what limitations and drawbacks it came with. Thanks for pointing that out!
I'm still stuck on the 'throw monkey' part... :(
@Corbin D: huh?
This reminds me another post if your's that detailed about the same thing. That got me started on plugins, thankfully. I would rather like it if you covered how to do this in other systems, like Xcode and some good Linux environment (gcc, eclipse, etc). I'd also love it if the kind of information was in the SDK itself eventually. I'll check out the new SDK when it comes out.
I think that you can never start off too simple -- and by that measure this is a good start. It may be too soon to get into it in this line of walk-throughs, but the main thing I hear people griping about is plugin debugging. I remember you (Aaron) discussing the new feature of RB and the debug plugins folder concept that helps address this. So all I can contribute is that it would be good to see that factored into this and include tips on how debugger settings should be configured to best work with plugin development.
This is very close, Aaron. It also should be part of the SDK docs (sorry, but you're the driver behind that).
I've run into the following issues that you do not cover:
Any further tips on these points?
Tim
@brumeister -- the stdafx files should not even be there, since you should have created an empty project. As for the PluginEntry link error, it sounds like you forgot to add the PluginEntry function to Main.cpp (perhaps you have a typo?).
After revisiting each step, the issue about the stdafx files is that prior VS2005 notes indicated that we should export symbols - which you can't do if you create an "Empty Project" as you outlined. I've recreated the solution and select ed Empty Project and the results are a simple complait about the 6 unrecognized #pragma settings.
Question- Is it no longer recommended to export symbols?
Otherwise, this has pretty much covered VS2005.
Tim
@brumeister -- correct, you should not export symbols. The previous documentation was in error when it said that it was needed (I think very old versions of the SDK may have required it, but don't recall).
As for the pragmas, those are harmless -- if you want to ignore the warnings, you can turn them off in the Advanced C++ tab, I think they're 4068, off the top of my head.
Excellent info.
I tried to follow your steps for creating a basic plugin dll. Right after
checking the empty project checkbox, I got lost. I don't know where to find the SDK code that you are trying to copy to the project folder, and so on. Could you please give some more info about where to find those SDK stuff? Thanks.
@SJ -- you get those files from your installation of REALbasic, or from the downloads page (for individual files). The interesting parts you want to copy over are in the Includes and Plugin Glue directories. | http://ramblings.aaronballman.com/2007/11/plugins_can_be_fun_part_one_vi.html | crawl-001 | refinedweb | 2,111 | 71.55 |
BIO_s_file, BIO_new_file, BIO_new_fp, BIO_set_fp, BIO_get_fp,
BIO_read_filename, BIO_write_filename, BIO_append_filename, BIO_rw_filename
- FILE bio
#include <openssl/bio.h>
BIO_METHOD * BIO_s_file(void);
BIO *BIO_new_file(const char *filename, const char *mode);
BIO *BIO_new_fp(FILE *stream, int flags);
BIO_set_fp(BIO *b,FILE *fp, int flags);
BIO_get_fp(BIO *b,FILE **fpp);
int BIO_read_filename(BIO *b, char *name)
int BIO_write_filename(BIO *b, char *name)
int BIO_append_filename(BIO *b, char *name)
int BIO_rw_filename(BIO *b, char *name)
BIO_s_file() returns the BIO file method. As its name implies
it is a wrapper round the stdio FILE structure and it is a source/sink BIO.
BIO_s_file()
Calls to BIO_read() and BIO_write() read and
write data to the underlying stream. BIO_gets() and
BIO_puts() are supported on file BIOs.
BIO_read()
BIO_write()
BIO_gets()
BIO_puts()
BIO_flush() on a file BIO calls the fflush()
function on the wrapped stream.
BIO_flush()
fflush()
BIO_reset() attempts to change the file pointer to the start
of file using fseek(stream, 0, 0).
BIO_reset()
fseek(stream,
BIO_seek() sets the file pointer to position ofs from start of file using fseek(stream, ofs, 0).
BIO_seek()
BIO_eof() calls feof().
BIO_eof()
feof().
Setting the BIO_CLOSE flag calls fclose() on the stream when
the BIO is freed.
fclose()
BIO_new_file() creates a new file BIO with mode mode the meaning of mode is the same as the stdio function fopen(). The BIO_CLOSE flag
is set on the returned BIO.
BIO_new_file()
fopen().
BIO_new_fp() creates a file BIO wrapping stream. Flags can be: BIO_CLOSE, BIO_NOCLOSE (the close flag) BIO_FP_TEXT (sets
the underlying stream to text mode, default is binary: this only has any
effect under Win32).
BIO_new_fp()
BIO_set_fp() set the fp of a file BIO to fp. flags has the same meaning as in BIO_new_fp(), it is a macro.
BIO_set_fp()
BIO_new_fp(),
BIO_get_fp() retrieves the fp of a file BIO, it is a macro.
BIO_get_fp()
BIO_seek() is a macro that sets the position pointer to offset bytes from the start of file.
BIO_tell() returns the value of the position pointer.
BIO_tell()
BIO_read_filename(), BIO_write_filename(),
BIO_append_filename() and BIO_rw_filename() set
the file BIO b to use file name for reading, writing, append or read write respectively.
BIO_read_filename(),
BIO_write_filename(),
BIO_append_filename()
BIO_rw_filename()
When wrapping stdout, stdin or stderr the underlying stream should not
normally be closed so the BIO_NOCLOSE flag should be set.
Because the file BIO calls the underlying stdio functions any quirks in
stdio behaviour will be mirrored by the corresponding BIO.
On Windows BIO_new_files reserves for the filename argument to be UTF-8
encoded. In other words if you have to make it work in multi- lingual
environment, encode file names in UTF-8.
File BIO ``hello world'':
BIO *bio_out;
bio_out = BIO_new_fp(stdout, BIO_NOCLOSE);
BIO_printf(bio_out, "Hello World\n");
Alternative technique:
BIO *bio_out;
bio_out = BIO_new(BIO_s_file());
if(bio_out == NULL) /* Error ... */
if(!BIO_set_fp(bio_out, stdout, BIO_NOCLOSE)) /* Error ... */
BIO_printf(bio_out, "Hello World\n");
Write to a file:
BIO *out;
out = BIO_new_file("filename.txt", "w");
if(!out) /* Error occurred */
BIO_printf(out, "Hello World\n");
BIO_free(out);
BIO *out;
out = BIO_new(BIO_s_file());
if(out == NULL) /* Error ... */
if(!BIO_write_filename(out, "filename.txt")) /* Error ... */
BIO_printf(out, "Hello World\n");
BIO_free(out);
BIO_s_file() returns the file BIO method.
BIO_new_file() and BIO_new_fp() return a file BIO
or NULL if an error occurred.
BIO_set_fp() and BIO_get_fp() return 1 for
success or 0 for failure (although the current implementation never return
0).
BIO_seek() returns the same value as the underlying
fseek() function: 0 for success or -1 for failure.
fseek()
BIO_tell() returns the current file position.
BIO_read_filename(), BIO_write_filename(),
BIO_append_filename() and BIO_rw_filename()
return 1 for success or 0 for failure.) | https://www.openssl.org/docs/crypto/BIO_s_file.html | CC-MAIN-2014-10 | refinedweb | 578 | 64.41 |
>>
Can we return this keyword from a method in java?
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The "this" keyword in Java is used as a reference to the current object, within an instance method or a constructor. Using this you can refer the members of a class such as constructors, variables, and methods.
Returning “this”
Yes, you can return this in Java i.e. The following statement is valid.
return this;
When you return "this" from a method the current object will be returned.
Example
In the following Java example, the class Student has two private variables name and age. From a method setValues() we are reading values from user and assigning them to these (instance) variables and returning the current object.
public class Student { private String name; private int age; public Student SetValues(){ Scanner sc = new Scanner(System.in); System.out.println("Enter the name of the student: "); String name = sc.nextLine(); System.out.println("Enter the age of the student: "); int age = sc.nextInt(); this.name = name; this.age = age; return this; } public void display() { System.out.println("name: "+name); System.out.println("age: "+age); } public static void main(String args[]) { Student obj = new Student(); obj = obj.SettingValues(); obj.display(); } }
Output
Enter the name of the student: Krishna Kasyap Enter the age of the student: 21 name: Krishna Kasyap age: 21
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On Fri, Mar 05, 2004 at 09:44:29PM -0800, Tom Lord wrote: > I don't understand what the subdir structure has to do with case > sensitivity. Can you explain? > > _If_ you are correct that case issues effect many (I've only ever > heard you complain) -- there are sane ways to handle that (i.e., with > a VU namespace handler). I believe I have complained as well :-) Well, not exactly complained, but pointed-out. I did this after managing to break an archive. The change was trying to rename the file, only changing case. > How do you cope with #include, btw? And, what does tar do? There are two primary case-preserving, case-insensitive filesystems in the world, Windows (FAT or NTFS), and MacOS (HFS, HFS+). When trying to open a file, the case is ignored. When creating, it is preserved in the name. Generally, utilities don't even have to be aware of this (tar isn't, for example). Most of the time, it doesn't matter. It only matters if you try to create a new entry that differs only in case. On these systems, it will replace or overwrite the old entry. For directories (the subdir structure), the two versions will be smashed together into one entry, and won't be searchable on a case-sensitive system. The only difference between the two is the rename call. MacOS considers this valid ('foo' can be renamed to 'Foo'), whereas Windows considers this an error. Personally, I think a case-insensitive filesystem is stupid (think Unicode). But, the two largest OS vendors ship with them, and I think we're stuck with them for a while. Dave | http://lists.gnu.org/archive/html/gnu-arch-users/2004-03/msg00285.html | CC-MAIN-2019-22 | refinedweb | 278 | 75.71 |
.
Note: This is in no way meant to be a suggested solution to deep-linking (it was more of an exercise in playing with Django for me). Take a look at SWFAddress for a JavaScript-based way of achieving the same goal.
If you're going to follow along, you'll need Adobe Flex (2 or 3), a copy of SWFObject, and a working Django installation (here's how I got started with Django on OS X).
Flex:
Create a new Flex application called DjangoSWF with the following code and publish it.
<?xml version="1.0" encoding="utf-8"?> <mx:Application xmlns: <mx:Label </mx:Application>
All this application does is read the value of a
FlashVar parameter called
url and display it in a Label component.
Next, let's write some Python code so Django can dynamically populate the URL based on the actual URL that the user entered.
Django:
Start a new Django project:
django-admin.py startproject djangoswf.
Create two folders in the project folder called
templates and
static.
In the templates folder, create a file called djangoswf.html:
<html lang="en"> <head> <meta http- <title>{{url}}</title> <script src="/static/swfobject.js" language="javascript"></script> </head> <body scroll="no"> <div id="djangoswf">Django SWF example. This requires Flash Player.</div> <script language="JavaScript" type="text/javascript"> /*<!--*/ var so = new SWFObject("/static/DjangoSWF.swf", "theswf", "100%", "100%", "9"); so.addVariable("url", "{{url}}"); so.write("djangoswf"); /*-->*/ </script> </body> </html>
In the static folder, place the Flex SWF (DjangoSWF.swf) and the SWFObject.js file.
Create a views.py file in your project:
from django.shortcuts import render_to_response def flash_url(request, url): return render_to_response("djangoswf.html", {"url": url})
This is your view, where all the heavy-lifting is done (confusingly, Django calls its Business Delegates "Views"). Basically, that one line of code renders your HTML template and passes a
url argument to it. In the template, that URL is passed to your Flex SWF via FlashVars (using the addVariable method of your SWFObject instance).
Next, edit the urls.py file:
from django.conf.urls.defaults import * from djangoswf.views import * urlpatterns = patterns('', (r'^static/(?P <path>.*)$', 'django.views.static.serve', {'document_root': 'static'}), (r'^(.*)', flash_url), )
This is where the magic happens. The Django Front Controller maps URLs to business methods using regular expressions.
The first URL mapping is for static content. Normally, you would use a web server like Apache to serve static content in a deployment environment, but for development purposes it makes sense to have Django serve them. The static content in this example is the SWFObject.js file and the Flex SWF.
The next line contains the deep-linking mapping for the Flex application. All it does is take any URL and passes it to the flash_url method as an argument. (The ordering of the lines is important as the URL mappings use short-circuit logic, starting from the top.)
Finally, run the development server (
python manage.py runserver) and hit to see the current URL getting passed to Flex.
In a real application, of course, you would change the application state to reflect the URL instead of merely displaying it.
If you're interested in deep linking in your Flash and Flex applications, check out SWFAddress.
Thanks for sharing Aral..
As long as you’re playing with Flex/Django you might want to take a look at pyamf (basically amfphp for python); they already have an example Django gateway:
Hi cynic,
Been playing with it
Don’t work for me. My Browser show me a single message “Django SWF example “This requires Flash Player.”. In urls.py I need to teel django the true path to static folder. | http://aralbalkan.com/1269 | crawl-001 | refinedweb | 612 | 68.16 |
Hello All,
I have a Java code which fetches SQL to populate the drop down box.
SQL is returning result in this order -
year_code year_description
5 2005
4 2004
3 2003
2 2002
The drop down build from the java program is showing the same order
However, I want to show the order like
2004
2005
2003
2002
How can I default the year code to 2004 when the SQL is returning the above order
What change I may need to incorporate in Java code or SQL ?? A code snippet will expedite and help me a lot.
Thanks for your feedback
Show Default Model Year (1 messages)
- Posted by: Server Side
- Posted on: February 27 2004 11:19 EST
Threaded Messages (1)
- Show Default Model Year by Paul Strack on February 27 2004 23:25 EST
Show Default Model Year[ Go to top ]
How exactly do you want to sort these? Current year first, then all other years in reverse order?
- Posted by: Paul Strack
- Posted on: February 27 2004 23:25 EST
- in response to Server Side
Doing bizaar sort operation can be hard in SQL, but not too bad in Java. The best way to handle this is with a java.util.Comparator that specifies your sort order. Here is a sketch, assuming your store your years as Integer objects.
public class YearComparator implements Comparator {
public int compare(Object o1, Object o2) {
Integer year1 = (Integer) o1;
Integer year2 = (Integer) o2;
if (year1.equals(year2)) return 0;
// Current year at the top:
Calendar now = Calendar.getInstance();
Integer currentYear = new Integer(now.get(Calendar.YEAR));
if (year1.equals(currentYear)) return 1;
if (year2.equals(currentYear)) return -1;
// Otherwise, sort in reverse order:
return (year2.intValue() - year1.intValue());
}
}
You can then sort the collection containing your years:
Collections.sort(years, new YearComparator());
Alternately, you can store your data in a tree map that uses your Comparator to determine sort order:
Map yearMap = new TreeMap(new YearComparator());
yearMap.put(yearData...); | http://www.theserverside.com/discussions/thread.tss?thread_id=24215 | CC-MAIN-2015-32 | refinedweb | 328 | 61.77 |
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I looked at these docs:
But they really skim over it.
Exactly how do I compile an Objective-C function and get it to work in Unity? Is it something I do using Xcode? If so, how do I set up a project in Xcode to do it? When I compile, do I get a compiled file of some sort that I have to add to my Unity Assets?
Thanks.
Really, no answers? Nobody is doing this?
which plugin do u want to add..????
I want to write and compile my own plugins so I can use native iOS functionality from within Unity's scripts. I think that's what plugins are for, if I'm not mistaken.
Answer by crazyKnight
·
Dec 08, 2011 at 06:29 AM
this is how you a call a function declared in xcode
using UnityEngine;
using System.Collections;
public class NativeMethod : MonoBehaviour {
[System.Runtime.InteropServices.DllImport("__Internal")]
extern static public int AwesomeFunction(int awesomeParameter);
private int temp;
void OnGUI()
{
if(GUI.Button(new Rect(10*(Screen.width)/100,10*(Screen.height)/100,25*(Screen.width)/100,20*(Screen.height)/100),"CallNativeFunction"))
{
PlayerPrefs.SetInt("Save",0);
temp = AwesomeFunction(5);
}
}
}
this is the code for the xcode side
AppController.h
#ifdef __cplusplus
extern "C" {
#endif
int AwesomeFunction(int awesomeParameter);
#ifdef __cplusplus
}
#endif
AppController.mm
int AwesomeFunction(int awesomeParameter)
{
// My awesome code goes here.
NSLog(@"Function pressed from unity with value %d",awesomeParameter);
if ([[NSUserDefaults standardUserDefaults] integerForKey: @"Save"] == 0) //to read playerpref set from unity
{
NSLog(@"value recieved from unity for save with value 0");
}
[[NSUserDefaults standardUserDefaults] setInteger: 42 forKey: @"Save"]; // set new value for playerpref
// you can call whichever plugin you want here in this function or if you want to return some value back to unity or whatever else you like
return 70;
}
Hope this helps....
Yes, thanks, that does help. But it doesn't tell me how to compile it and what files are a result of the compile, and what I do with said file(s) after compiling. Would I put the file in the Unity project's Assets folder somewhere?
you dont have to put the files in unity asset folder...
lets go by an example suppose you have to add inapp plugin to ur game...
1.Copy the sdk provided for the inapp in your xcode project.
2. now you can call the method required for the inapp(from the sdk) in the method awesome function as declared above.
3. now when the inapp is successful you can send a confirmation back to unity by changing the value set for playerpref as i shown in the code above or there are many other ways to do it i am just suggesting how i would do that.
now if you ask how to use the sdk methods in xcode then you have to go to stackoverflow and search there ...
Thanks, but I don't want to call someone else's sdk. I just want to know how to create an xcode plugin project from scratch like your example above, then compile it, and any other steps required to make it so I can make calls to it from Unity. I understand how to make calls to it, but I don't know how to set up the plugin project and compile it.
$$anonymous$$aybe I'm misunderstanding how it works overall. $$anonymous$$aybe I don't compile the plugin? $$anonymous$$aybe it is added to the xcode project that is generated by Unity when I build?
The docs are confusing (go figure). At the top it says this:
"In order to use a plugin you need to do two things:
Write a plugin in a C based language and compile it.
Create a C# script which calls functions in the plugin to do something."
Then it goes on to say this:
"Add your native implementation to the generated XCode project's "Classes" folder (this folder is not overwritten when project is updated, but don't forget to backup your native code)."
So based on the first statement, I expected to compile a plugin by itself, not as part of the generated project. But the second statement says to put it in the generated project.
Answer by crazyKnight
·
Dec 08, 2011 at 07:41 AM
@ Gillissie : see there are two ways to create a plugin
1.Write a plugin in c based language compile it and then copy it to the plugin folder in your unity project and then call the methods as per your need
2 call a static extern function in unity,build the project,go to xcode created build,declare and define the function called in unity and do your required in that specific function
i would prefer the 2 ways as i have done enough work on objective c before coming to unity so it helps me there,and i am kinda of confused what you are actually trying to do can you just be a little more precise of what you actually want to create maybe i can suggest you a more easy way out ....
sorry that should have been a comment...
I want to get access to native iOS properties, such as locale, and maybe sqlite3 database support for saving games. I want to do things that you can do on an iPhone but not natively in Unity.
Answer by crazyKnight
·
Dec 08, 2011 at 07:56 AM
okay so now suppose you want to get the device locale in unity so what you can do here is
write this code in the native function ou created in xcode(awesome function in the code provided above)
int AwesomeFunction(int awesomeParameter)
{
NSString * language = [[NSLocale preferredLanguages] objectAtIndex:0];
}
This will return a two letter code for the currently selected language. "en" for English, "es" for Spanish, "de" for German, etc. For more examples, please see this Wikipedia entry (in particular, the 639-1 column):
so now you have the locale in the variable which you can return to unity and do whatever changes you want to do based on the locale,
you can either return it as a return type or set it in player prefs and read it in unity.
correct me if i took your question wrong.
I appreciate your help, but this isn't answering my question. However, I think I may be able to figure it out based on bits and pieces that I can gather from this whole conversation.
The question isn't how to get the locale (that was just one example of what I want to do with plugins), the question is how to get it working. I think the answer lies in the fact that there are two different kinds of plugins.
Compiled plugins that are dll's that must be in the Assets folder of the Unity project. These have nothing to do with iOS.
Native device plugins like iOS, where the "plugin" code lives in the generated Xcode project and is compiled as part of the generated Xcode project, not separately.
From what I gather, what I want is #2.
Thanks for your help. I have it figured out now. The Bonjour example project helped me too.
Answer by mannu
·
Jul 18, 2012 at 02:22 PM
I have developed game application in unity and give login facility from facebook. i used the AppController.mm to login from facebbok and its working fine but i need if user login from facebook and return to the game then game will start automatically, so needed one function to call from AppController to unity for test user is looged or not. it is possible, anyone can build is including Mac OSX .bundle files into Xcode Project
2
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iOS - Disable ARC on XCode Projects
2
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Call Unity class in XCode
1
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Linker error when creating a static iOS library that depends on another static library.
1
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0
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Intro to Vue.js: Vuex
This is the fourth part in a five-part series about the JavaScript framework, Vue.js. In this part, we’ll cover Vuex for state management.
- Vuex (You are here!)
- Animations (Coming soon!)
Vuex
If you missed the last few sections on components and Vue-cli, you might want to go review those before reading on. Now that we know the very basics about how components and passing state and props around, let’s talk about Vuex. It’s a useful tool for state management.
Previously, we’ve passed state from a top level component down, and siblings did not share data. If they needed to talk to each other, we’d have to push the state up in the application. This works! But once your application reaches a certain complexity, this no longer makes sense to do. If you’ve worked with Redux before, all of these concepts and the implementation will be familiar to you. Vuex is basically Vue’s version of Redux. In fact, Redux will work with Vue as well, but with Vuex, you have the benefit of using a tool designed to work specifically with your framework.
First, we’ll install Vuex:
npm install vuex
or
yarn add vuex
I set it up this way: within my `/src` directory, I create another directory named store (this is a preference, you could also just create a `store.js` file in that same directory), and a file named `store.js`. The initial set up in `store.js` would look something like this (vstore sublime snippet):
import Vue from 'vue'; import Vuex from 'vuex'; Vue.use(Vuex); export const store = new Vuex.Store({ state: { key: value } });
key: value is a placeholder for any kind of state data. In other examples we’ve used
counter: 0.
In our `main.js` file, we’d perform the following updates (updated lines highlighted):
import Vue from 'vue'; import App from './App.vue'; import { store } from './store/store'; new Vue({ el: '#app', store: store, template: '<App/>', components: { App } });
After we get it set up, we can place our
data() in the file as the state as we’ve previously done with components, and then we’ll either use this state or update it with the following three means:
- Getters will make values able to show statically in our templates. In other words, getters can read the value, but not mutate the state.
- Mutations will allow us to update the state, but they will always be synchronous. Mutations are the only way to change data in the state in the store.
- Actions will allow us to update the state, asynchronously, but will use an existing mutation. This can be very helpful if you need to perform a few different mutations at once in a particular order.
Sometimes it’s difficult to understand why you might work with asynchronous state changes if you haven’t before, so let’s first go over how that would happen in the abstract and then dive into something real in the next section. Let’s say you’re Tumblr. You have a ton of heavy gifs on a page that doesn’t end for a long time. You only want to load a certain amount at a time, say 20, until the user gets 200px away from the bottom of the original page.
You could have a mutation that displays the next 20. But you don’t have the next 20 yet, nor do you know when you hit the bottom of the page. So, in the app itself, you create an event that listens to the scroll position and you trigger an action.
The action then retrieves the URLs from the database for the next 20 images, and wraps the mutation, which adds the 20 images to the state and displays them.
Actions, in essence, create a framework for requesting data. They give you a consistent way to apply the data in an asynchronous manner.
Most Basic Abstract Example
In the example below, we’re showing the most basic implementation of each, so you get a sense of the setup and how it would work. Payload is an optional parameter. You can define the amount you are updating the component by. Don’t worry, we’ll use an actual demo in a moment, it’s just important to get the base concepts first.
In `store.js`:
export const store = new Vuex.Store({ state: { counter: 0 }, //showing things, not mutating state getters: { tripleCounter: state => { return state.counter * 3; } }, //mutating the state //mutations are always synchronous mutations: { //showing passed with payload, represented as num increment: (state, num) => { state.counter += num; } }, //commits the mutation, it's asynchronous actions: { // showing passed with payload, represented as asynchNum (an object) asyncDecrement: ({ commit }, asyncNum) => { setTimeout(() => { //the asyncNum objects could also just be static amounts commit('decrement', asyncNum.by); }, asyncNum.duration); } } });
A really nice feature here is we can return the entire state object in the mutations, but we don’t have to, we can just use what we need. Time travel debugging (walking through the mutations to find errors) will still work either way.
On the component itself, we would use
computed for getters (this makes sense because the value is already computed for us), and
methods with
dispatch to access the mutations and actions:
In `app.vue`:
computed: { value() { return this.$ store.getters.value; } }, methods: { increment() { this.$ store.dispatch('increment', 2) } }
Or, you can use a spread operator. I find this useful when you have to work with a lot of mutations/actions:
export default { // ... methods: { ...mapActions([ 'increment', // map this.increment() to this.$ store.commit('increment') 'decrement', 'asyncIncrement' ]) } }
Simple Real Example
Let’s look at the Weather Notifier App again, with a very small and simple amount of state in the Vuex store. Here’s the repo.
See the Pen Vue Weather Notifier by Sarah Drasner (@sdras) on CodePen.
In `store.js`:
import Vue from 'vue'; import Vuex from 'vuex'; Vue.use(Vuex); export const store = new Vuex.Store({ state: { showWeather: false, template: 0 }, mutations: { toggle: state => state.showWeather = !state.showWeather, updateTemplate: (state) => { state.showWeather = !state.showWeather; state.template = (state.template + 1) % 4; } } });
Here, we’re setting the state of
showWeather, this is set to false at first because we don’t want any of the animations firing right away, not until the user hits the phone button. In mutations, we’ve set up a toggle for the state of
showWeather.
We’re also setting the
template to 0 in the state. We’ll use this number to cycle through each of the weather components one by one. So in mutations, we’ve created a method called
updateTemplate. This both toggles the state of
showWeather, and updates the
template to the next number, but it will wrap around to zero when it hits the number 4.
In App.vue:
<template> <div id="app"> ... <g id="phonebutton" @ ... </g> <transition @ <g v- <app-droparea</app-droparea> <app-windarea</app-windarea> <app-rainbowarea</app-rainbowarea> <app-tornadoarea v-else></app-tornadoarea> </g> </transition> ... </div> </template>
<script> import Dialog from './components/Dialog.vue'; ... export default { computed: { showWeather() { return this.$ store.state.showWeather; }, template() { return this.$ store.state.template; } }, methods: { updateTemplate() { this.$ store.commit('updateTemplate'); } }, ... components: { appDialog: Dialog, ... } } </script>
In `dialog.vue`:
<script> export default { computed: { template() { return this.$ store.state.template; } }, methods: { toggle() { this.$ store.commit('toggle'); } }, mounted () { //enter weather const tl = new TimelineMax(); ... } } </script>
In the code above, App uses
showWeather to advance the template, while Dialog merely toggles the component visibility. You can also see that in App.vue, we are showing and hiding different child components based on the value of template in the App
<template> with that snazzy conditional rendering we learned in the first article. In App, we’re both listening to the changes of state in store with the
computed values, and using
toggle() and
updateTemplate() in the methods to commit to the store’s mutations.
This is a basic example, but you can see how with a complex app with tons of state, it would be helpful to manage the state all in one place, rather than moving it up and down our components. Particularly when siblings need to talk to siblings.
If you’re interested in digging into Vuex deeper, there are great docs here. You might have noticed that we used some
<transition> components in this last demo, as well as lot of animations. Let’s talk about that next!
Article Series:
- Rendering, Directives, and Events
- Components, Props, and Slots
- Vue-cli
- Vuex (You are here!)
- Animations (Coming soon!)
Intro to Vue.js: Vuex is a post from CSS-Tricks | http://design-lance.com/intro-to-vue-js-vuex/ | CC-MAIN-2018-26 | refinedweb | 1,436 | 65.62 |
This article is about a file preview control (see the figure below). You may find such a file preview control helpful when you need to display content of a file as text, hexadecimal (HEX) dump or as an image. The control is based on WTL's CStatic control - that means you can use the code in your WTL-based application. You can preview your files as HEX, text (Latin-1) and image (BMP) formats. File size doesn't matter - the control can preview even huge files without noticeable delays, because it loads the file in a separate thread.
CStatic
The article provides a simple demo application and the source code of the control.
Some time ago, I needed a way for previewing content of files for one of my open-source projects - CrashRpt, a crash reporting library for Windows applications. When your app crashes, the CrashRpt library generates an error report archive containing some files, such as crash minidump, error logs, desktop screenshots and so on. And user should be able to review the file contents before sending the error report over the Internet. So, I needed a control for previewing files in HEX, text and image format (see the figure below).
CrashRpt
Browsing the web didn't give me a control that fully sufficed my needs, so I decided to write my own control. This article describes a light-weight file preview control that can preview Latin-1 text files, binary files in HEX and BMP image files, because I don't want to overweight the code with additional library dependencies (libpng, libjpeg, and so on). But if you need more capabilities (UTF-8 and UTF-16 text preview, JPEG and PNG image preview), you may refer to CrashRpt source code and find the original, more powerful file preview control.
libpng
libjpeg
Using the control in your WTL application is very simple. You just need to copy FilePreviewCtrl.h and FilePreviewCtrl.cpp files to your project directory and add those files to your Visual C++ project. Put a static control on your dialog and set static control's name to IDC_PREVIEW. Next add the #include "FilePreviewCtrl.h" line to the beginning of your dialog's header file and add CFilePreviewCtrl m_filePreview; member variable to your dialog's (or window's) class. Finally, in your OnInitDialog() handler, subclass the static control by adding the following line:
static
IDC_PREVIEW
#include "FilePreviewCtrl.h"
CFilePreviewCtrl
Fi
lePreviewCtrl
m_filePreview;
OnInitDialog()
m_filePreview.SubclassWindow(GetDlgItem(IDC_PREVIEW));
Below there are several methods provided by CFilePreviewCtrl class that you can use to preview files and customize control's behavior.
To open the file for preview, use SetFile() method. To get the name of the currently previewed file, use GetFile() method.
SetFile()
GetFile()
// Returns the file name of the current file
LPCTSTR GetFile();
// Sets current file and preview mode.
// You can pass NULL as file name to clear the preview.
BOOL SetFile(LPCTSTR szFileName, PreviewMode mode=PREVIEW_AUTO);
To set the current preview mode, use SetPreviewMode() method. Using the GetPreviewMode() allows to get the current preview mode.
SetPreviewMode()
GetPreviewMode()
// Returns current preview mode
PreviewMode GetPreviewMode();
// Sets current preview mode
void SetPreviewMode(PreviewMode mode);
The preview mode is defined by the PreviewMode enumeration (see below). As you can see, the file preview control can detect the preview mode automatically (PREVIEW_AUTO constant) or you can force another preview mode by specifying PREVIEW_HEX, PREVIEW_TEXT or PREVIEW_IMAGE constant.
PreviewMode
PREVIEW_AUTO
PREVIEW_HEX
PREVIEW_TEXT
PREVIEW_IMAGE
// Preview mode
enum PreviewMode
{
PREVIEW_AUTO = -1, // Auto
PREVIEW_HEX = 0, // Hex
PREVIEW_TEXT = 1, // Text
PREVIEW_IMAGE = 2 // Image
};
You can use the DetectPreviewMode() method to determine what preview mode will be automatically chosen for a certain file.
DetectPreviewMode()
// Detects a correct preview mode for certain file
PreviewMode DetectPreviewMode(LPCTSTR szFileName);
When there is nothing to preview, the file preview control displays empty screen with "No data to display" message on the top. You can override the text message by using SetEmptyMessage() method.
SetEmptyMessage()
// Sets the text to display when nothing to preview (the default is "No data to display")
void SetEmptyMessage(CString sText);
For HEX preview mode, it is possible to modify the number of bytes per line displayed by calling the SetBytesPerLine() method.
SetBytesPerLine()
// Sets count of bytes per line for Hex preview
BOOL SetBytesPerLine(int nBytesPerLine);
One may ask how the file preview control autodetects the correct preview mode? It does this using two ways: by file extension and by file heading bytes.
First it checks file extension. If the file extension is TXT, INI, LOG, XML, HTM, HTML, JS, C, H, CPP, HPP, then the control assumes this is a text file. If not, the control loads first several bytes of the file and compares it with the BMP file signature (all BMP files have "BM" magic characters in the beginning of the file). If the signature matches, the control assumes the file is a bitmap image file. If not, the control assumes the file is an unknown binary file and selects the HEX preview mode for it.
BM
And some words on how this control previews huge text, image and binary files so rapidly.
Two things contribute to its preview speed: usage of file mapping and multithreading.
A file mapping is a Win32 object allowing you to map an arbitrarily large file to the operating memory and access only the part of the file by creating file view. This way, you can rapidly access any portion of the large binary file without wasting the memory and without time delays. You can find the CFileMemoryMapping class in the FilePreviewCtrl.h header file. Below the declaration of the CFileMemoryMapping class is presented:
CFileMemoryMapping
FilePreviewCtrl.h
// Used to map file contents into memory
class CFileMemoryMapping
{
public:
CFileMemoryMapping();
~CFileMemoryMapping();
// Initializes the file mapping
BOOL Init(LPCTSTR szFileName);
// Closes the file mapping
BOOL Destroy();
// Returns memory-mapped file size
ULONG64 GetSize();
// Creates a view for a portion of the memory-mapped file
LPBYTE CreateView(DWORD dwOffset, DWORD dwLength);
private:
HANDLE m_hFile; // Handle to current file
HANDLE m_hFileMapping; // Memory mapped object
DWORD m_dwAllocGranularity; // System allocation granularity
ULONG64 m_uFileLength; // Size of the file.
CCritSec m_csLock; // Sunc object
std::map<DWORD, LPBYTE> m_aViewStartPtrs; // Base of the view of the file.
};
The CFileMemoryMapping::Init() method uses CreateFile() and CreateFileMapping() WinAPI functions for initializing the file mapping object. Creating the file mapping doesn't actually allocate a memory. The memory allocation is performed in CFileMemoryMapping::CreateView() method that uses MapViewOfFile() API call to memory-map a small portion (view) of the file and returns the pointer to it. When the allocated view is not needed anymore, it is unmapped with the help of UnmapViewOfFile() API call.
CFileMemoryMapping::Init()
CreateFile()
CreateFileMapping()
CFileMemoryMapping::CreateView()
MapViewOfFile()
UnmapViewOfFile()
The CFileMemoryMapping class allows to create several views at the same time to access them from different threads simultaneously. The created views are stored in CFileMemoryMapping::m_aViewStartPtrs variable.
CFileMemoryMapping::m_aViewStartPtrs
Multithreading is used when you need to perform a time-consuming work without blocking the main thread. To do the work asynchronously, another thread is created with the help of CreateThread() WinAPI function and called the worker thread. The file preview control performs text file parsing in that another thread (text parsing is needed to determine line breaks). And it loads an image in another thread, too. You can find out how it does this by looking at the code of CFilePreviewCtrl::DoInWorkerThread() private method.
CreateThread()
CFilePreviewCtrl::DoInWorkerThread()
While the worker thread performs image loading or text parsing, the main thread displays the portions that are ready for preview on timer events (WM_TIMER message). Scrollbars are also updated on timer. When the worker thread finishes loading file, it sends the WM_FPC_COMPLETE private message to the file preview control window to notify it about completion.
WM_TIMER
WM_FPC_COMPLETE
The asynchronous loading/parsing operation may even be cancelled when user opens another file for preview. To cancel the operation, the main thread sets the CFilePreviewCtrl::m_bCancelled flag and waits for worker thread's exiting. When the worker thread encounters the cancel flag, it returns from the thread procedure.
m_bCancelled. | http://www.codeproject.com/Articles/203020/FilePreviewCtrl-Preview-Files-in-Text-HEX-and-Imag | CC-MAIN-2014-35 | refinedweb | 1,331 | 52.39 |
Testing Props in Vue components using Jest
In this tutorial, we are going to learn about how to test props in vue components using jest and vue-test-utils.
Props in vue components help us to pass the data from parent components to child components.
The example component we are testing.
<template> <h1>{{title}}</h1></template> <script> export default { props:['title']}; </script>
In the above component, we have declared a
prop called
title.
When we unit test a component we need to provide a correct prop to the component at the time of mounting. so that we can test does the component is receiving correct props are not.
In vue-test-utils
shallowMount method takes an
options object as a second argument by using this object we can pass props to the component.
Let’s write a test for the
Post.vue component.
import Post from '../src/components/Post.vue' import { shallowMount } from '@vue/test-utils'; describe('Testing Component props', () => { const wrapper = shallowMount(Post, { propsData: { title: "First post" //passing prop to component } }); it('checks the prop title ', () => { expect(wrapper.props().title).toBe('First post'); }) })
In the above code, we first passed a prop to the component inside
shallowMount method and it returns a
wrapper object which contains a
props() method.
The
props() method returns an
object containing props of the component currently have, like in the above code we are asserting the prop
title has a value
First post. | https://reactgo.com/vue-test-props/ | CC-MAIN-2020-16 | refinedweb | 239 | 53.21 |
ALF/architecture/ALF Schemas 1
Contents
Introduction
ALF Event Manager Schemas and WSDL version 1
WARNING: THIS PAGE IS BEING CONSTRUCTED. THE INFORMATION IT CONTAINS IS PRELIMINARY
The proposed version 1 ALF Event schema is presented below.
Some of the features to note are:
1. The provision for extension and versioning using nested "Extension" elements. The approach pursued is based primarily on the recommendations of this article, "Extensibility, XML Vocabularies, and XML Schema" by David Orchard[1]. This is discussed in more detail below.
2. The refactoring of the BaseEvent to divide it into two parts; the part normally set by the tool raising the event and the part normally set by the alf event manager. The primary motivation for this is to establish a structure of elements that can be passed on to the services of "alf compliant" tools. The needs of this structure correspond to those elements that are normally set by the event manager.
3. There are various name changes and a few additional fields
4. The concept of "User" has been simplified to an extensible "credentials" type. There is now no assumption that a user will be represented by a name, login and password.
5. The need to declare derived types and services to allow tools to decfine their events has been addressed. The declared services, the event manager and the example service flow services, have been changed to use WS-I complient RPC Literal style. Previously, Document Literal style was prefered but that proved problematic for type overloading. The details are discussed under Vocabularies section (Event Declaration Schema).
NOTE: While the schema and WSDL are valsi an WS-I complient we have discovered that curent versions of some web service tools have limitations that mean they cannot consume the WSDL and Schema. These problems are mostly to do with the use of restricting facets (eg: attributes such as minOccurs="0") Given this we may need to make some minor adjustments to the schema before it is final.
Versioning
The approach to versioning in the ALFEvent schema is as follows
1. Namespace The namespace of the ALFEvent schema is "\alf\......\1". The trailing 1 designates the schema as major version 1. If it becomes necessary to version the schema, this namespace will be retained so long as the changes are compatible with the existing schema. That is, existing documents created with the exisitng schema will still validate against the new version of the schema. Generally this means that additions are allowed but the removal of elements, changing of structure or changing of types are not allowed. Changes that make the new schema incompatible require that the namespace be changed. Generally we might expect a version 2 to be incompatible and the namespace to become "\alf\......\2". This ensures that there is no confusion between what is compatible and what is not. At this time we do not anticipate the need to make incompatible changes.
2. Designated Extension Points Generally it is not possible to change the structure of a data type in a compatible way. To get around this we designate particular extension points where additiona elements may be added in the future should the need arise. Schema provides a way of indicating that "any" element may follow but it presents some challenges as described here (article reference) The general advice is to create a marker element that contains the "any" since this ensure that whatever is substituted into the "any" is disambiguated from the preceeding elements.
3. Separate Extension Points for different purposes The ALF Event Schema is intended to be specialized by tools to allow them to declare their events. While the same principle is used for both extensions due to versioning and extensions due specialization it is important that these do not clash. Special sections are designated as being instended for Vocabulary extensions and for Custom extensions. These are separate from the various various extension points that are included to handle potential additions to the base schema.
4. Provision for dynamic version selection Event though the goal is for new versions in the same namespace to be compatible with the previous version there may be a need to dynamically detect the version in use. To address this, a specific Version attribute is defined the intent of which is to enumerate all the various version numbers that are covered by the specifc schema. The intent is that a tool that raises events would set this attribute to the approriate value fo the version of the schema they are using when the create an event "document". A consumer of the event "document" can then examine this value as a hint to identify which version of the schema is being used. The problem with this mechanism is that it relies on the originating tool to set the attribute correctly and this is not enforcable.
Schema 1
Example 1 Event Document
WSDL 1
Event Declaration
See Section [Event Declaration Schema] | http://wiki.eclipse.org/ALF/architecture/ALF_Schemas_1 | CC-MAIN-2020-10 | refinedweb | 823 | 51.28 |
In the previous recipe, we learned how to get data from an API using
fetch. In this recipe, we will learn how to POST data to the same endpoint to add new bookmarks.
Before going through this recipe, we need to create an empty app named
SendingData. You can use any other name; just make sure you set the correct name when registering the app.
index.ios.jsand
index.android.jsfiles, remove the previous code, and add the following:
import React from 'react'; import { AppRegistry } from 'react-native'; import MainApp from './src/MainApp'; AppRegistry.registerComponent('SendingData', () => MainApp);
src/MainApp.jsfile, import ...
No credit card required | https://www.safaribooksonline.com/library/view/react-native-cookbook/9781786462558/ch04s04.html | CC-MAIN-2018-26 | refinedweb | 105 | 57.67 |
Follow me on Twitter, happy to take your suggestions on topics or improvements
React is widely used library for client side web applications. In any web applications, there will be multiple pages. routing the URL properly and load different pages based on route parameters is a general requirement.
There is an awesome npm package which takes all the complexity to serve the purpose of routing in React.
react-router-dom is one of the widely used react library.
Basic routing
Lets create two simple pages
/)
- About page (
/about)
Create a simple react app using
create-react-app CLI. Its very easy with npx -
npx create-react-app my-react-app
// App.js import React from 'react'; const App = () => { return ( <section className="App"> <h1>React routing Example</h1> </section> ); }; export default App;
Lets create two pages. In simple terms two functional react component.
// App.js ... const IndexPage = () => { return ( <h3>Home Page</h3> ); }; const AboutPage = () => { return ( <h3>About Page</h3> ); }; ...
Before diving deep into react router code, First lets understand, what are all needed for routing a page in react application.
- There will be links to navigate between pages.
- Define Route to the pages. It define the URL path and component to load for the URL.
- Define a Router which will check whether the requested URL exist in the defined Routes.
Lets create the links and routes using react router's
Link and
Route components. First install the package
yarn add react-router-dom.
// App.js ... import { Link, Router as BrowserRouter, Route } from 'react-router-dom'; ... const App = () => { return ( <section className="App"> <Router> <Link to="/">Home</Link> <Link to="/about">About</Link> <Route path="/" component={IndexPage} /> <Route path="/about" component={AboutPage} /> </Router> </section> ); };
Let's go through each line separately
import { Link, Router as BrowserRouter, Route } from 'react-router-dom';
Here we are importing three components,
Linkcomponent will create HTML link to the pages.
Routecomponent will define the routes.
Routercomponent will handle the logic of routing. When user click the link, it check whether this link exist in route definition. If it exists, then the router will change the URL in browser and route will render the correct component.
BrowserRouter is one type of router, it is also the widely used router. It uses HTML5 push state underneath the component to route your pages.
We will discuss in more details about different types of router later in this series.
// Link with URL <Router> <Link to="/">Home</Link> <Link to="/about">About</Link> </Router>
Router should be the parent component enclosing
Link and
Route. So that it can handle the routing. If we place the Link or Route outside it won't work. It will throw an error.
Link accept
to props which defines the URL it want to link.
Why do we need Link component, why not a HTML anchor tag with href?
- HTML
atag will create a server side link. So each time, a user click on the route, it won't check the router or the routes. Instead it simply redirect the page in the browser to that route.
- Whereas Link, check the router and the router check the route and load the component without reloading the page in the browser. Thats why it is called as client side routing. It doesn't load the page from the server while clicking on the Link component.
// Route with definition <Route path="/" component={IndexPage} />
Here
Route have path and component props.
component props helps to render the component when user comes to this route.
path props define the url path to be matched when user visits the page.
If you go ahead and check whether our routes are working, it will work. But it have a small glitch.
If you click about link, it will render both
IndexPage and
AboutPage component in its page. Why 🤔
Because the path defined for about is
/about. Here router traverses through the route definitions from top to bottom. First checks the Route with path
/ and the about URL have
/, so it renders IndexPage component first. And then it checks the next Route
/about, that also matches, so it renders AboutPage component.
How to match exact route?
Its very simple, the question itself have the answer 😎. Use
exact props in Route.
... const App = () => { return ( <section className="App"> <Router> <Link to="/">Home</Link> <Link to="/about">About</Link> <Route exact path="/" component={IndexPage} /> <Route exact path="/about" component={AboutPage} /> </Router> </section> ); }; ...
exact prop will help to match the route only if the whole route matches as it is, else it won't render the component.
Now both the component will render fine and the Link will work properly.
Thats all folks, you have already completed the part 1 of Deep dive into React Router series. Hope you enjoyed and learned few things for your next big react app 🤗
You can checkout the codebase for this series here and the code for this section here
Note: This article was originally written for my blog. I am republishing it here for the amazing DEV community.
Discussion (0) | https://dev.to/paramharrison/basic-routing-in-react-using-react-router-406e | CC-MAIN-2021-43 | refinedweb | 837 | 74.49 |
Hello,
we're using the Intel C++ compiler and came across some unexpected behaviour when compiling code containing the volatile modifier. We managed to narrow it down to the following demo code (please see inline comments):
// save as demo.cc // volatile "bug"? struct counter { // XXX bug seems to only occur when using bitfield #if defined(NO_BITFIELD) unsigned int value_; #else unsigned int value_ : 32; #endif }; struct counter_container { struct counter counter_; inline int get_counter() volatile { return counter_.value_; } }; class Demo { public: counter_container* pCounter_container_; int counter(int x) { // XXX bug wrt/ volatile?! #if defined(UNEXPECTED) int ret = static_cast(pCounter_container_ + x)->get_counter(); #else // only this seems to work as expected volatile int ret = (pCounter_container_ + x)->get_counter(); #endif return ret; } Demo() : pCounter_container_(0) { return; } int play() { // this loop is omitted when compiling with -DUNEXPECTED while (counter(0x1234) != 0) { } return 42; } }; int main() { Demo demo; return demo.play(); }
Now use the commands in the following shell script to compile and look at the assembler output:
#!/bin/bash # volatile "bug"? # $ icc -V ICC_REFERENCE='Intel C Intel 64 Compiler Professional for applications running on Intel 64, Version 11.0 Build 20090318 Package ID: l_cproc_p_11.0.083 Copyright (C) 1985-2009 Intel Corporation. All rights reserved.' set -e DEMO="demo.cc" echo "Reference version: $ICC_REFERENCE " echo "Using version: $(icc -V 2>&1) " read -p 'Press Enter to compile $DEMO (or ^C to quit) ...' -n1 -s echo icc -S -fsource-asm -O2 -x c++ "$DEMO" -o "$(basename "$DEMO").ok.s" icc -S -fsource-asm -O2 -x c++ -DUNEXPECTED "$DEMO" -o "$(basename "$DEMO").bad.s" if [ -x "$(which vimdiff)" ] then read -p 'Press Enter to start vimdiff (or ^C to quit) ...' -n1 -s echo vimdiff "$(basename "$DEMO").ok.s" "$(basename "$DEMO").bad.s" else echo "Look at diff $(basename "$DEMO").ok.s $(basename "$DEMO").bad.s!" fi
We believe that in the "unexpected" case the compiler shouldn't be allowed to optimize/leave out the "volatile" reads to counter_->value_ in the while loop. Is this correct? Or is the version with static_cast not supposed to work at all? Any comments or insights are appreciated!
Regards
Oliver | https://software.intel.com/en-us/forums/intel-c-compiler/topic/291423 | CC-MAIN-2017-34 | refinedweb | 347 | 59.4 |
Board index » C Language
All times are UTC
----------------- 1st program------------------
main() { int a, b,ans; printf("Type two intergers:"); scanf("%d%d", &a, &b); ans=formula(a,b); printf("The sum of the squares is %d", ans);
cc program_name.c -o executable_name
If the <math.h> functionality is used, you also have to add `-lm' at the end of the command line.
>----------------- 1st program------------------
>main() >{ >int a, b,ans; >printf("Type two intergers:"); >scanf("%d%d", &a, &b);
printf("The sum ... is %d\n", ans);
Also, provide a successful exit status from main() with
return 0;
>--------------------- 2nd program ------------------- >main() >{ >formula(int x,int y) >{ >return (x*x + y*y); >}
Why don't you purchase a C tutorial textbook and possibly a reference manual so that you can learn C properly? I suggest the second edition of _The C Programming Language_ by Brian Kernighan and Dennis Ritchie, which has plenty of tutorial material and is aimed at people with programming experience. As a reference manual, I would recommend the latest edition of Harbison and Steele.
It looks like you're trying to reference a function (formula) from the 1st program (let's call it 1st_program.c from now on) in the 2nd program (let's call it 2nd_program.c from now on). What you need to do is modify 1st_program.c like this:
#include <stdio.h> /*so printf and scanf will work*/ #include "formula.h" /*so the program can find formula*/
main() /*main really returns an int and has some args, but don't worry *about it. */ { int a, b, ans ; printf("Type two integers:"); /*spell integers correctly*/ scanf("%d%d", &a, &b); ans=formula(a,b); printf("The sum of the squares is %d", ans);
/*you could have combined the formula and printf calls like so: *printf( "The sum of the squares is %d", formula(a,b) ); */
int formula(int x,int y) /*if you included a function prototype, all *you would need here would be formula( x, y ) */ { return (x*x +y*y);
$ gcc -o myprogram 1st_program.c 2nd_program.c
Thanks for at least making an effort at doing the job yourself before posting to the newsgroup. Usually people just want their homework done. It appears to me that you gave a try (although maybe not the hardest try ;->).
Jay
scribbled :
>Regards.. Nameir
Then, chmod 700 file, and type ./file to run it. -- Revised anti-spam in use : remove X to reply - 'Xnetbook' becomes 'netbook'
Anti-spam thermonuclear warheads cheap at only $300!
2ndprogram.exe: cc -o 2ndprogram.exe " 2nd program "
Now type "make -n -f omigod.i'm.too.dumb.to.use.a.manual". make will print out a list of commands; drag over these commands with the left mouse button, then press the middle mouse button. If you haven't got a three button mouse, go cry at a user support services person.
By the way, neither of those is even close to a C program; the first refers to a function that is never defined, the second tries to begin a function definition inside main(), which is not allowed, and never finishes main.
If you had asked this in the right place, I would have given useful advice. As is, this is really more intended as a bit of stress relief for all of the other people who came here hoping to find something about *C* to read.
-s -- Copyright 1997 Peter Seebach - seebs at solon.com - C/Unix Wizard
The *other* C FAQ, the hacker FAQ, et al. Unsolicited email (junk mail and ads) is unwelcome, and will be billed for.".
Ian R. Hay - Toronto, Canada ----------------------------------------------------------------------
> scribbled : >
> You don't need a makefile. > Just type the name of the compiler (gcc, cc, hpcc) and then the name of > the C file, and see what happens.
BTW, makefiles are not features of standard C. They are programming tools, mostly distruibuted with some compilers. For help on creating makefiles for a Unix compiler, it's best to ask the Unix programming experts in:
Stephan (initiator of the campaign against grumpiness in c.l.c)
> Anti-spam thermonuclear warheads cheap at only $300!
>Whatever happened to self-reliance?
--
``Not only is UNIX dead, it's starting to smell really bad.'' -- rob
>".
> Out of all the bad and inappropriate questions posted here recently, why > pick on this poor guy? It's your only post in a while, Seebs; there > must be better prey.
It's a sad fact that there are only a few capable of writing such fine examples of sarcastic humour and they do not have the time to comment all the stupid questions in c.l.c
Stephan (initiator of the campaign against grumpiness in c.l.c)
1. Making files "Installable"
2. Home made file save dialog box
3. Home made file save dialog box
4. Shortcut code makes file but it doesn't work ?
5. Making a static LIB files instead of DLL files
6. Making a new function or simulating the making
7. Exe made by MSVC5.0 and Dlls made by 6.0 causes problem
8. Exe made by MSVC5.0 and Dlls made by 6.0 causes problem
9. MAKING an EXE file in Vc++ .Net
10. making a File readonly
11. Making .dll file through C programming
12. making a header file... | http://computer-programming-forum.com/47-c-language/1d929e85f96ebcfb.htm | CC-MAIN-2019-09 | refinedweb | 882 | 74.79 |
Opened 10 years ago
Closed 10 years ago
Last modified 10 years ago
#1828 closed Bug (No Bug)
Strange behavior with IniWrite
Description
Hello, a member of the French forum point us for a strange behavior of the WriteIni command if you use FileOpenDialog before and don't specifies the path of the ini file.
This is the simple test script :
#include <GUIConstants.au3> Global $Var = "C:\MyDir1\MyDir2\MyDir3\MyFile.exe" GUICreate('',180,50) $Button1 = GUICtrlCreateButton("Get File Path", 5, 5, 80, 40) $Button2 = GUICtrlCreateButton("Write ini", 90, 5, 80, 40) GUISetState() While 1 $nMsg = GUIGetMsg() Switch $nMsg Case $GUI_EVENT_CLOSE Exit Case $Button1 $Var = FileOpenDialog("Select a file", @DesktopDir, "(*.*)") Case $Button2 IniWrite("Test.ini", "Parameters", "Var", $Var) EndSwitch WEnd
If you click "Write ini" button before doing anything else, the file is created.
If you click "Get File Path" button before, the IniWrite action doesn't work ...
After some searches, we have noticed that if we specifies the path of the ini file, the IniWrite action always work ...
The documentation doesn't specifies if the full path of the inifile must be used. So is it a bug or did we miss something?
Attachments (0)
Change History (2)
comment:1 Changed 10 years ago by Jos
- Resolution set to No Bug
- Status changed from new to closed
comment:2 Changed 10 years ago by Tlem
I nevertheless read the help of both functions, but I had not dreaded the impact of this little sentence.
Thank you very much.
Guidelines for posting comments:
- You cannot re-open a ticket but you may still leave a comment if you have additional information to add.
- In-depth discussions should take place on the forum.
For more information see the full version of the ticket guidelines here.. | https://www.autoitscript.com/trac/autoit/ticket/1828 | CC-MAIN-2021-04 | refinedweb | 294 | 61.36 |
Clean Code: Explanation, Benefits, and Examples
Clean Code: Explanation, Benefits, and Examples
To paraphrase Martin Fowler, good code isn't just readable by a machine, but by humans as well. Read on for some advice on sticking to clean principles.
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Every year, a tremendous amount of time and significant resources are lost because of poorly written code. Developers very often rush because they feel pressure from their managers or from the client to get the job done quickly, sometimes even sacrificing on quality. This is a big issue nowadays and therefore I decided to write an article about clean code, where I want to show all the benefits of clean coding and of building the software project right from the beginning.
What Is Clean Code?
I want to start this article with a very good quote: “Any fool can write code that a computer can understand. Good programmers write code that humans can understand.” – Martin Fowler.
This quote explains the essence of clean coding.
When we talk about clean code, we talk about a reader-focused development style that produces software that’s easy to write, read, and maintain. Clean code is code that is easy to understand and easy to change.
The word “clean” has become very trendy nowadays if you look at design, photography, etc. people go for clean things because nowadays our life is extremely complicated and we want to choose clean and clear options because it calms us down and saves us precious time. It's the same in software development and architecture, if you have more code than you need, it shouldn’t be there, there shouldn’t be anything extra.
Your code should be as efficient, readable, and maintainable as possible, and instead of only solving the problem, you should always put a bit of extra time in to focus on the design of your code, on architecture. Your code should be understandable, should be clean. This means the code is easy to read, whether that reader is the original author of the code or somebody else. There shouldn’t be doubts and misunderstandings. For example, the following should be clear: the execution flow of the application, how different objects collaborate with each other, the role and responsibility of each class, each method purpose, purpose of each expression and variable, etc.
Also, it is extremely important to have the ability to easily extend and refactor your code. This can be achieved if the person making the changes understands the code and also feels confident that the changes introduced in the code do not break any existing functionality. For the code to be easy to change, you need to be sure that you took into account that classes and methods are small and only have a single responsibility, that classes have clear and concise public APIs, classes and methods are predictable and work as expected, the code is easily testable and has unit tests, that tests are easy to understand and easy to change, etc.
What is important to keep in mind is that a clean coder makes sure he fully understands the problem before beginning to code. It is just like building a house: the foundation and architecture are key! In the long term, it will save you time and money on “redoing” work.
8 Reasons Why Clean Code Matters
1. Clearness
It’s easy to forget that each line of code software developers write is likely to be read many times by humans during its lifetime. These humans are usually co-workers. They’re busy fixing bugs and adding features. Therefore each developer should take care of the code and make it as clean and clear as possible. Developers are like authors, great authors are known for writing books that tell a clear, compelling story. They use chapters, headings, and paragraphs to clearly organize their thoughts and painlessly guide their reader. Developers work in a very similar system, but use namespaces, classes, and methods instead of words.
2. Best Practices
In recent years, software best practices like unit testing, TDD, CI, etc. have been growing very fast in terms of adoption. These practices elevate code quality and maintainability. Implementing clean code principles is a foundational skill that pays off especially well when it’s time to refactor code or bring code under testing. Clean code makes it easier to read and test. If you think of it as part of a house, clean code is the foundation.
3. Logic Behind the Code
If someone asks you about your code quality, you should provide a rational justification. If you’ve never methodically considered the quality of your coding style, there’s likely plenty of opportunity for improvement. Those who write clean code have concrete activities, patterns, and techniques they use to keep their code clean.
4. Maintenance
Writing code is relatively easy, reading is hard. This is why so many developers prefer to rewrite rather than do the hard work of reading and comprehending existing code. By writing code that is readable, you are optimizing for the 90% of the time we are reading code, rather than the 10% of the time you are writing it. This is a significantly more cost-effective strategy than the alternative strategy of writing code as quickly as possible without concern for the readability of the code. Also, it makes it almost impossible to say, “Oh, this code is not mine, it is Juan’s.” With clean code you won’t need to blame others for the poor quality of the code, clean code is a standard, a foundation for everyone to work on. So, at the end of the day, by creating code that is maintainable, you are optimizing the majority of your time and the cost of maintaining code.
5. Easy to Test
By building clean code, automated testing of that code is encouraged. By automated testing, I mean Test-Driven Development - which is the most effective way to improve the quality of code, improve the long-term velocity of a team, and reduce the number of software defects. All of these factors contribute heavily to the overall ROI of the software.
6. Simplicity
Keep your code as simple and readable as possible. Don’t over-complicate problems, which is a common issue among software developers. By keeping it simple, you can produce higher quality code, solve problems faster ,and work better in groups.
At Apiumhub, we love the KISS principle (keep it simple, stupid), as well as the DRY principle, which means don’t repeat yourself. It allows software developers to avoid duplication and allows them to produce much cleaner code compared to the programmer who uses unnecessary repetition.
And don’t add extra features because you might need them in the future. Never do that. It’s a useless waste of time and money. And it’s actually harmful. When you over complicate the code by adding extra features, you are making the code harder to read, understand, maintain, and test. By doing this, you’re creating bugs in your code. And you don’t know the future, and nine out of ten times your assumption will be wrong. Even if you were right that a feature would be necessary later, it might only be needed two years from now, and by then, you might have found a better way to do it. Focus on MVP.
7. Consistency
Imagine you go to a shop and there is no consistency over how the items are placed in the area. It would be hard to find the products you are searching for. Indentation in the code is much like the arrangement that you need in a supermarket. When your code is indented, it becomes more readable and easier to find what you’re looking for. Especially when you pay attention to the names of the items. Having a proper naming convention is extremely important in code for future edits. Having irrelevant or contradicting names for your pages, variables, functions or arrays will only create trouble for you in the future. Therefore, naming elements on the basis of what they are is a common rule helps a lot. It creates consistency and makes it easier to come back and work on the project at a later time.
Actually, this leads us to the next step for clean code – creating a common language, or a “ubiquitous language,” if you follow the ideas of Domain Driven Design. It seems obvious, but unfortunately, many developers skip this part. So, once again, I would like to repeat that the wording of code is very important because you want your variable names, class names, and package names to make sense no matter who is looking at the code.
8. Cost Savings
By doing clean code, you gain all those advantages listed above, and all of them lead to cost savings.
As a conclusion, I would like to say that you shouldn't be afraid to defend your project and your code. Build quality, working software and take as much time as you need.
Many managers defend the schedule and requirements with passion, but that’s their job. It’s your job to defend your clean code with equal passion! It helps to increase the overall value, and reduce the overall cost, of both creating and maintaining software. It does this by focusing on creating reader-centric code that is simple, readable, understandable, testable, and maintainable.
If you are interested in knowing more about clean code, I recommend you to read these 2 books, written by Robert C. Martin:
Published at DZone with permission of Ekaterina Novoseltseva . See the original article here.
Opinions expressed by DZone contributors are their own.
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{{ parent.linkDescription }}{{ parent.urlSource.name }} | https://dzone.com/articles/clean-code-explanation-benefits-amp-examples | CC-MAIN-2020-10 | refinedweb | 1,642 | 61.87 |
Mach-o, but wrong architecture
This appears to be a constant refrain.
Attempting to run a simple tutorial app:
import sys
import PySide.QtCore
import PySide.QtGui
app = PySide.QtGui.QApplication(sys.argv)
label = PySide.QtGui.Qlabel("Hello World")
label.show()
app.exec_()
sys.exit()
The import fails as follows:
Traceback (most recent call last):
File "/Users/lewislevin/Dropbox/Python-code/QT-hello-world/Hello-world.py", line 4, in <module>
import PySide.QtCore
ImportError: dlopen(/Library/Python/2.7/site-packages/PySide/QtCore.so, 2): no suitable image found. Did find:
/Library/Python/2.7/site-packages/PySide/QtCore.so: mach-o, but wrong architecture
I initially installed PySide with pip and ran the post install script. Import works and the version can be displayed with the trivial test.
But, it produced same message. I uninstalled with pip (which doesn't really work of course as PySide is scattered to many places. generally, you should have a reliable uninstaller. Perish the thought that someone might ever want to uninstall...)
Then, I used brew and to install a build Pyside, which installed a new copy of QT. Everything is at version 4.8.6. The trivial test works:
Python 2.7.8 (v2.7.8:ee879c0ffa11, Jun 29 2014, 21:07:35)
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
import PySide
import PySide.QtCore
print (PySide.QtCore.version)
4.8.6
But, there is this mach-o incompatibility. This is frustrating.
- SGaist Lifetime Qt Champion
Hi and welcome to devnet,
You might be mixing 32bit and 64bit libraries. You can check that with the file command
How do you run that command?
- SGaist Lifetime Qt Champion
@file /path/to/the_file_you_want_to_check@ | https://forum.qt.io/topic/44073/mach-o-but-wrong-architecture | CC-MAIN-2017-39 | refinedweb | 294 | 55.2 |
Please have patience with me on this. I just started reading a book about C and it instructed me to type the following:
#include <stdio.h>
void main()
{
char txt[80];
printf("Enter data:");
scanf("%s",txt);
printf(txt);
}
When compiling (gcc) I got 2 messages:
lots of dirs and then about file crt1.o it said "in function '_start':"
and the second line same dirs and about file crt01.a(.txt+0x18)and then the message "undefined reference to main"
as it talks about txt i changed the declaration to 20 (i thought perhaps the line is too long, but the same message keeps apearing.
There is probably a very easy explanation but I just dont know enough yet to find it myself. Anyone please? | https://cboard.cprogramming.com/c-programming/7692-stupid-scanf-question.html | CC-MAIN-2017-26 | refinedweb | 126 | 77.37 |
Animate content offset
I am not having much luck animating content offset. When the view loads I want the scrollview to glide to the offset position. Any tips implementing the
ui.animate()function.
import ui w, h = ui.get_screen_size() sv = ui.ScrollView() sv.frame = (0,0,w,h) sv.background_color = 'gray' sv.content_size = (0, 2000) y_offset = 1000 sv.present() sv.content_offset = (0, y_offset) #animate me
Something like this should work:
# ... def scroll(): sv.content_offset = (0, y_offset) ui.animate(scroll, 0.5)
Great thanks. Now I get it.
Alternative, if you don't like nested functions:
from functools import partial ui.animate(partial(setattr, sv, 'content_offset', (0, y_offset)), 0.5)
(I find this a bit harder to read though.)
Oooo. Cleaver. That is definitely for the pros. I like it.
iirc lambdas also work, and might be slightly easier to read than partial. | https://forum.omz-software.com/topic/2438/animate-content-offset/1 | CC-MAIN-2021-10 | refinedweb | 142 | 64.98 |
INET6(4) BSD Programmer's Manual INET6(4)
inet6 - Internet protocol version 6 family
#include <sys/types.h> #include <netinet/in.h>
The inet6 family is an updated version of the inet(4) family. While inet(4) implements Internet Protocol version 4, inet6 implementsorder. The include file <netinet/in.h> defines this address as a discriminated union. Sockets bound to the inet6 family utilize the following addressing struc- ture: struct sockaddr_in6 { u_int8_t sin6_len; sa_family_t sin6_family; in_port effect "wildcard" matching on incoming messages. The IPv6 specification defines scoped address, like link-local or site- local address. A scoped address is ambiguous to the kernel, if it is specified without a scope identifier. To manipulate scoped addresses properly from userland, programs must use the advanced API defined in RFC 2292. A compact description of the advanced API is available in ip6(4). If scoped addresses are specified without explicit scope, the kernel may raise an error. Note that scoped addresses are not for daily use at this moment, both from a specification and an implementation point of view. KAME implementation supports extended numeric IPv6 address notation for link-local addresses, like "fe80::1%de0" to specify "fe80::1 on de0 interface". The notation is supported by getaddrinfo(3) and getnameinfo(3). Some normal userland programs, such as telnet(1) or ftp(1), are able to use the notation. With special programs like ping6(8), an outgoing interface can be specified with an extra command line option to disambiguate scoped addresses. Scoped addresses are handled specially in the kernel. In the kernel structures like routing tables or interface structure, scoped addresses will have their interface index embedded into the address. Therefore, the address on some of the kernel structure is not the same as that on the wire. The embedded index will become visible on PF_ROUTE socket, kernel memory accesses via kvm(3) and some other occasions. HOWEVER, users should never use the embedded form. For details please consult. Note that the above URL describes the situation with the latest KAME tree, not the OpenBSD tree..
OpenBSD does not route IPv4 traffic to an AF_INET6 socket. The particular behavior in RFC 2553 is intentionally omitted for security reasons presented above. If both IPv4 and IPv6 traffic need to be accepted, listen to two sockets. The behavior of AF_INET6 TCP/UDP socket is documented in RFC 2553. Basi- cally, it says the following: • A specific bind to an AF_INET6 socket (bind(2) with address specified) should accept IPv6 traffic to that address only. • If a wildcard bind is performed IPv6 address like ::ffff:10.1.1.1. This is called IPv4 mapped address. • If there are both wildcard bind AF_INET socket and wildcard bind AF_INET6 socket on one TCP/UDP port, they should behave separately. IPv4 traffic should be routed to AF_INET socket and IPv6 should be routed to AF_INET6 socket. However, RFC 2553 does not define the constraint between the order of bind(2), nor how IPv4 TCP/UDP port numbers and IPv6 TCP/UDP port numbers relate to each other (should they be integrated or separated). Implement- ed behavior is very different from kernel to kernel. Therefore, it is un- wise to rely too much upon the behavior of AF_INET6 wildcard bind socket. It is recommended to listen to two sockets, one for AF_INET and another for AF_INET6, if both IPv4 and IPv6 traffic are to be accepted. It should also be noted that malicious parties can take advantage of the complexity presented above, and are able to bypass access control, if the target node routes IPv4 traffic to AF_INET6 socket. Caution should be taken when handling connections from IPv4 mapped addresses to AF_INET6 sockets.
ioctl(2), socket(2), sysctl(3), icmp6(4), intro(4), ip6(4), tcp interface is defined in RFC 2553 and RFC 2292. The im- plementation described herein appeared in WIDE/KAME project.
The IPv6 support is subject to change as the Internet protocols develop. Users should not depend on details of the current implementation, but rather the services exported. "Version independent" code should be implemented as much as possible in order to support both inet(4) and inet6. MirOS BSD #10-current January 29, 1999. | https://www.mirbsd.org/htman/sparc/man4/inet6.htm | CC-MAIN-2016-07 | refinedweb | 698 | 56.66 |
Hi Dan,
some comments below...
On Tue, 2006-10-03 at 14:19 -0400, Dan Diephouse wrote:
> As I understand it, we would need to integrate CXF at two points. First,
> the deployment. We need to support JSR 109 deployment descriptors.
> Second, we need to support invoking EJBs.
>
> For deployment, we can wire in JSR 109 descriptors into the service
> construction. In CXF we have a Service, which holds a WSDL like service
> model and information about CXF can invoke the server (like databinding
> info, interceptors/handlers, etc). Generally you create a Service from a
> ServiceFactory [2][3]. The base service factory
> (ReflectionServiceFactoryBean) can actually construct the service from
> WSDL using the WSDLServiceFactory or from introspection. During this
> construction, ServiceConfigurations [4] can provide values for the
> service. There can be many of these. For instance, lets say we want to
> determine the namespace of the service. We can have a
> JaxWsServiceConfiguration which takes the namespace from the @WebService
> attribute. If there is no specified namespace, the service factory will
> move to the DefaultServiceConfiguration which will create a namespace
> from the package name. With that all said - its easy to envision how a
> Jsr109ServiceConfiguration could be created to override values in the
> JAX-WS attributes. I still don't know enough about JSR109 to say if this
> will be sufficient though - It would be good to come up with a list of
> areas that JSR 109 affects.
I'm not overly familiar with CXF's service model stuff but this sounds
reasonable.
With JEE5 and Web Services 1.2, deployment descriptors optional so the
CXF web service builder must be able to introspect the deployment
archive and find suitably annotated classes.
> The second area - EJB invocation - is a bit simpler. In CXF we have the
> concept of Invokers [5][6]. Invokers allow you to control how your
> object is invoked. You can supply your own object, scopes, etc. XFire
> had an EJB invoker [7] which I think is similar to what needs to happen
> here (although I know jack about EJBs, so I could be wrong). While the
> Invoker interface in CXF is slightly different, all the same information
> is there.
I did some work with the Geronimo Web Service container and Celtix 1.0,
although that was with a WS endpoint implemented using a servlet. For
the servlet case, the integration was done as a custom Celtix transport
that sat atop the Geronimo web service container. The transport was G's
but the bindings and dispatch were handled by Celtix.
Currently with Geronimo, are EJBs invoked on through the same Web
Service Container? If so, then CXF may need to adapt to the WS
container as well as using the EJB invoker. If not, is the plan for CXF
to supply the whole WS stack, including transport?
And not forgetting support servlet endpoints.
> Are there other integration areas that I missed here? Anyone able to
> provide a more comprehensive view of what exactly we need to do in terms
> of JSR 109?
On the client side, injection of @WebServiceRef annotations need to be
supported. I guess this would come under some general resource
injection framework for Geronimo, but CXF will need to be able to hook
into it to provide proxies for the referenced services
On the builder side of thing, I'll dust off the old Celtix one and see
how out of date it is.
rgds
Conrad
> Cheers,
> - Dan
>
>
> 1.
> 2.
>
> 3.
>
> 4.
>
> 5.
>
> 6.
>
> 7.
>
>
> David Jencks wrote:
> >
> >
>
> | http://mail-archives.apache.org/mod_mbox/geronimo-dev/200610.mbox/%[email protected]%3E | CC-MAIN-2017-22 | refinedweb | 581 | 65.22 |
New releases from Python and Jython on their way
The Python 3.5 proposal supports async and await syntax, while Jython 2.7 gets faster in its latest instalment. We check out what’s new with the object-oriented programming language and the successor to JPython.
In Python Enhancement Proposal (PEP) #0492, Python 3.5 will support asynchronous programming with the inclusion of async and await syntax, making coroutines a native Python language feature. With this proposal, Yury Selivanov hopes to “keep Python relevant and competitive in a quickly growing area of asynchronous programming”.
The PEP shows how the new syntax is used to declare a native coroutine:
async def read_data(db): pass
Key properties of the new feature mean that
async def functions are always coroutines, even if they do not contain
await expressions. The PEP states that it’s a
SyntaxError to have
yield or
yield from expressions in an
async function. The new coroutine declaration syntax also internally introduces two new code object flags:
CO_COROUTINEis used to enable runtime detection of coroutines (and migrating existing code)
CO_NATIVE_COROUTINEis used to mark native coroutines (defined with new syntax)
All coroutines have
CO_COROUTINE ,
CO_NATIVE_COROUTINE, and
CO_GENERATOR flags set.
As for
await expressions, these are used to obtain a result of coroutine execution:
async def read_data(db): data = await db.fetch('SELECT ...') ...
Some examples of
await expressions have been published in the PEP as the following:
A full list of expressions, complete with invalid syntax examples and further information, can be found in the above mentioned PEP #0492.
Jython 2.7.0 final released
Jython developer Frank Wierzbicki has announced the release of Jython 2.7 after several betas and three release candidates. Described as complementary to Java, the Python-implementation language boasts language and runtime compatibility with CPython 2.7 and substantial support of the Python ecosystem.
SEE ALSO: Java + Python: Jython 2.7 beta 3 has arrived
New features include built-in support of pip/setuptools and a native launcher for Windows (bin/jython.exe), with the implication that you can now install Jython scripts on Windows.
Jim Baker appeared at PyCon 2015 and presented demos and new features of Jython’s latest shipment, which can be see here. | https://jaxenter.com/new-releases-from-python-and-jython-117078.html | CC-MAIN-2021-17 | refinedweb | 370 | 53.71 |
Thanks Jeff and sorry for bothering you again!
I got clear the remoting writing into HDFS, but what about hadoop process?
Once the file has been copied to HDFS, do I still needs to run
hadoop -jarfile input output everytime?
if I need to do it everytime, should I do it from remote server as well?
Thank for helping and for your patience
-- Gerardo
On Thu, Aug 28, 2008 at 5:10 PM, Jeff Payne <[email protected]> wrote:
> You can use the hadoop command line on machines that aren't hadoop servers.
> If you copy the hadoop configuration from one of your master servers or
> data
> node to the client machine and run the command line dfs tools, it will copy
> the files directly to the data node.
>
> Or, you could use one of the client libraries. The java client, for
> example, allows you to open up an output stream and start dumping bytes on
> it.
>
> On Thu, Aug 28, 2008 at 5:05 PM, Gerardo Velez <[email protected]
> >wrote:
>
> > Hi Jeff, thank you for answering!
> >
> > What about remote writing on HDFS, lets suppose I got an application
> server
> > on a
> > linux server A and I got a Hadoop cluster on servers B (master), C
> (slave),
> > D (slave)
> >
> > What I would like is sent some files from Server A to be processed by
> > hadoop. So in order to do so, what I need to do.... do I need send those
> > files to master server first and then copy those to HDFS?
> >
> > or can I pass those files to any slave server?
> >
> > basically I'm looking for remote writing due to files to be process are
> not
> > being generated on any haddop server.
> >
> > Thanks again!
> >
> > -- Gerardo
> >
> >
> >
> > Regarding
> >
> > On Thu, Aug 28, 2008 at 4:04 PM, Jeff Payne <[email protected]> wrote:
> >
> > > Gerardo:
> > >
> > > I can't really speak to all of your questions, but the master/slave
> issue
> > > is
> > > a common concern with hadoop. A cluster has a single namenode and
> > > therefore
> > > a single point of failure. There is also a secondary name node process
> > > which runs on the same machine as the name node in most default
> > > configurations. You can make it a different machine by adjusting the
> > > master
> > > file. One of the more experienced lurkers should feel free to correct
> > me,
> > > but my understanding is that the secondary name node keeps track of all
> > the
> > > same index information used by the primary name node. So, if the
> > namenode
> > > fails, there is no automatic recovery, but you can always tweak your
> > > cluster
> > > configuration to make the secondary namenode the primary and safely
> > restart
> > > the cluster.
> > >
> > > As for the storage of files, the name node is really just the traffic
> cop
> > > for HDFS. No HDFS files are actually stored on that machine. It's
> > > basically used as a directory and lock manager, etc. The files are
> > stored
> > > on multiple datanodes and I'm pretty sure all the actual file I/O
> happens
> > > directly between the client and the respective datanodes.
> > >
> > > Perhaps one of the more hardcore hadoop people on here will point it
> out
> > if
> > > I'm giving bad advice.
> > >
> > >
> > > On Thu, Aug 28, 2008 at 2:28 PM, Gerardo Velez <
> [email protected]
> > > >wrote:
> > >
> > > > Hi Everybody!
> > > >
> > > > I'm a newbie with Hadoop, I've installed it as a single node as a
> > > > pseudo-distributed environment, but I would like to go further and
> > > > configure
> > > > a complete hadoop cluster. But I got the following questions.
> > > >
> > > > 1.- I undertsand that HDFS has a master/slave architecture. So master
> > and
> > > > the master server manages the file system namespace and regulates
> > access
> > > to
> > > > files by clients. So, what happens in a cluster environment if the
> > master
> > > > server fails or is down due to network issues?
> > > > the slave become as master server or something?
> > > >
> > > >
> > > > 2.- What about Haddop Filesystem, from client point of view. the
> client
> > > > should only store files in the HDFS on master server, or clients are
> > able
> > > > to
> > > > store the file to be processed on a HDFS from a slave server as well?
> > > >
> > > >
> > > > 3.- Until now, what I;m doing to run hadoop is:
> > > >
> > > > 1.- copy file to be processes from Linux File System to HDFS
> > > > 2.- Run hadoop shell hadoop -jarfile input output
> > > > 3.- The results are stored on output directory
> > > >
> > > >
> > > > There is anyway to have hadoop as a deamon, so that, when the file is
> > > > stored
> > > > in HDFS the file is processed automatically with hadoop?
> > > >
> > > > (witout to run hadoop shell everytime)
> > > >
> > > >
> > > > 4.- What happens with processed files, they are deleted form HDFS
> > > > automatically?
> > > >
> > > >
> > > > Thanks in advance!
> > > >
> > > >
> > > > -- Gerardo Velez
> > > >
> > >
> > >
> > >
> > > --
> > > Jeffrey Payne
> > > Lead Software Engineer
> > > Eyealike, Inc.
> > > [email protected]
> > >
> > > (206) 257-8708
> > >
> > >
> > > "Anything worth doing is worth overdoing."
> > > -H. Lifter
> > >
> >
>
>
>
> --
> Jeffrey Payne
> Lead Software Engineer
> Eyealike, Inc.
> [email protected]
>
> (206) 257-8708
>
>
> "Anything worth doing is worth overdoing."
> -H. Lifter
> | http://mail-archives.apache.org/mod_mbox/hadoop-common-user/200808.mbox/%[email protected]%3E | CC-MAIN-2017-39 | refinedweb | 804 | 72.46 |
Recurrent Neural Networks, Long Short Term Memory and the famous Attention based approach explained
When you delve into the text of a book, you read in the logical order of chapter and pages and for a good reason. The ideas you form, the train of thoughts, it’s all dependent on what you have understood and retained up to a given point in the book. …
Paper summary and code.
Deep convolutional neural networks have led to a series of breakthroughs for image classification tasks.
Challenges such as ILSVRC and COCO saw people exploiting deeper and deeper models to achieve better results. Clearly network depth is of crucial importance.
Due to the difficult nature of real world tasks or problems being thrown at deep neural networks, the size of the networks is bound to increase when one wants to attain high levels of accuracy on deep learning tasks. …
I came across multiple solutions to access files from Google drive in Colab notebooks asking to install wrappers or utilities and what not.
However, accessing files from Google drive can be done just with these 2 lines of code:
from google.colab import drivedrive.mount('/content/drive')
This will generate a url in Colab, click that, which will open up a new tab, choose your Google account, allow access. This will generate a token, copy that and paste back in the blank field in Colab.
After the drive has been mounted follow the next step.
Now to access files from drive: prefix this…
A curious being, developer, interested in AI and other technological advancements | https://manu1992.medium.com/ | CC-MAIN-2021-17 | refinedweb | 261 | 61.36 |
Python33 September 2012
You can download the version you like free from:
As of 2013 stick with Python27 or Python33.
Selfextracting MS Installer files have a .msi extension and contain the version number, for instance python-3.3.2.msi.
Python3 is not totally campatible with Python2. A few clumsy things have been removed to modernize the language. One obvious one is the print statement, which is now a print() function and raw_input() has been changed to just input(). The old numeric input() is gone.
You can find an excellent discussion of Python2 to Python3 changes here:
(check appendix A for Py2-to-Py3 differences)
The good news is that Python3 contains a conversion program 2to3.py that will convert your present Python2 code to Python3 code. C: drive, so I ended up with a C:\Python33 folder after the installation. The first step is to create a subfolder (subdirectory) for all your test programs, like D:\Python33\Atest33.
C:\Python33).
print( "Hello Monty Python!" ) ...
str1 = "Hello Monty Python!" # this is a comment # notice you don't have to declare the variable type print( str1 ) ...
str1 = "Hello Monty Python!" # let's replace the M with Spam str2 = str1.replace('M', 'Spam') # one more Spam for the P str3 = str2.replace('P', 'Spam') # now look at the result print( str1 ) print( str2 ) print( str3 )).
For GUI programming there are third party modules available:
Tkinter usually comes with the Python installation
wxPython and project Phoenix at
PyQT at
PySide at
I recommend PySide.
The Python Image Library (PIL) is at:
The PyGame module for game programming is at:
Also look at this site for other Python third party modules:
(mostly binary Windows installers)!
In order to visualize the execution of your Python code line by line use
On my iPad I use an app called "Pythonista" that does a nice job with Python 2.7 (also has PIL).):
def function_name(arg1, arg2, ...): statement block return arg3, arg4, ... ....
def get_name(): """this function only returns arguments""" first = "Fred" last = "Ferkel" return first, last def show_name(name): """this function only receives an argument""" print( name ) def process_name(first, last): """this function reveives 2 arguments, returns 1 argument""" name = "Mr. " + first +" " + last return name def main(): """ this function handles the other functions in order ...
def f1(): print('f1') # call function f2 f2() def f2(): print('f2') f3() def f3(): print('f3') # all function have been defined # this will work fine f1()
Here a call is made before define ...
def f1(): print('f1') # call function f2 f2() # oops, premature call, this will give # NameError: global name 'f2' is not defined f1() def f2(): print('f2') f3() def f3(): print('f3')
Many Pythonians prefer this style of commenting functions ...
def formatDollar(amount): """ a function to format to $ currency (this allows for multiline comments) """ return "$%.2f" % amount print( formatDollar(123.9 * 0.07) ) print( formatDollar(19) )
There is another use for the triple quoted comment or documentation string. You can access it like this ...
# accessing the documentation string # (these are double underlines around doc) print( formatDollar.__doc__ )
A more complete example ...
import math) print( "Distance between point(1,3) and point(4,7) is", getDistance(1,3,4,7) ) print( "Distance between point(1,3) and point(11,19) is", getDistance(1,3,11,19) ) print( '-'*50 ) # print 50 dashes, cosmetic print( "The function's documentation string:" ) # shows comment between the triple quotes)
Just a note on function or variable names, avoid using Python language keywords or Python's builtin function names. For a list of Python's builtin functions (also called methods) you can use this little code:
builtin_fuction_list = dir(__builtins__) print( builtin_fuction_list ) print( "-"*70 ) # print a decorative line of 70 dashes # or each function on a line using a for loop for funk in builtin_fuction_list: print( funk ) print( "-"*70 ) # or each function on a line joining the list to a string print( '\n'.join(builtin_fuction_list) ) print( "-"*70 ) # or, a little more advanced, combine it all and do a case insensitive sort too print( '\n'.join(sorted(dir(__builtins__), key = str.lower)) )
Sorry, couldn't resist showing off the different ways to present the data.
To get a list of Python keywords use:
from keyword import kwlist print( kwlist ).
When you write a Python program like ...
# use slicing to spell a string in reverse str1 = "Winners never quit, quitters never win!" # slicing uses [begin : end : step] # end is exclusive # defaults are begin = 0, end = len of string, step = 1 # use step = -1 to step from end print( "reverse = ", str1[::-1] )
....
# use slicing to spell a string in reverse str1 = "Winners never quit, quitters never win!" # slicing uses [begin : end : step] # end is exclusive # defaults are begin = 0, end = len of string, step = 1 # use step = -1 to step from end print( "reverse = ", str1[::-1] ) # optional wait for keypress raw_input('Press Enter...') # ...
# slicing uses [start:<end:step] s4 = "hippopotamus" print( "first 2 char = ", s4[0:2] ) print( "next 2 char = ", s4[2:4] ) print( "last 2 char = ", s4[-2:] ) print( "exclude first 3 char = ", s4[3: ] ) print( "exclude last 4 char = ", s4[:-4] ) print( "reverse the string = ", s4[::-1] ) # step is -1 print( "the whole word again = ", s4 ) print( "spell skipping 2 char = ", s4[::2] ) # step is 2 """ my output --> first 2 char = hi next 2 char = pp last 2 char = us exclude first 3 char = popotamus exclude last 4 char = hippopot reverse the string = sumatopoppih the whole word again = hippopotamus spell skipping 2 char = hpooau """
You can apply slicing to any indexed sequence, here is a list example ...
# exploring Python's slicing operator # can be used with any indexed sequence like strings, lists, ... # syntax --> seq[begin : end : step] # step is optional # defaults are index begin=0, index end=len(seq)-1, step=1 # -begin or -end --> count from the end backwards # step = -1 reverses sequence # if you feel lost, put in the defaults in your mind # use a list as a test sequence a = [0, 1, 2, 3, 4, 5, 6, 7, 8] print( a[3:6] ) # [3,4,5] # if either index is omitted, beginning or end of sequence is assumed print( a[:3] ) # [0,1,2] print( a[5:] ) # [5,6,7,8] # negative index is taken from the end of the sequence print( a[2:-2] ) # [2,3,4,5,6] print( a[-4:] ) # [5,6,7,8] # extract every second element print( a[::2] ) # [0, 2, 4, 6, 8] # step=-1 will reverse the sequence print( a[::-1] ) # [8, 7, 6, 5, 4, 3, 2, 1, 0] # no indices just makes a copy (which is sometimes useful) b = a[:] print( b ) # [0, 1, 2, 3, 4, 5, 6, 7, 8] # slice in (replace) an element at index 3 b[3:4] = [100] print( b ) # [0, 1, 2, 100, 4, 5, 6, 7, 8] # make another copy, since b has changed b = a[:] # slice in (insert) a few elements starting at index 3 b[3:] = [9, 9, 9, 9] + b[3:] print( a ) # [0, 1, 2, 3, 4, 5, 6, 7, 8] print( b ) # [0, 1, 2, 9, 9, 9, 9, 3, 4, 5, 6, 7, 8]
Python has a very helpful feature called help(). Here is a sample ...
# list all the modules Python currently knows about ... help("modules") # now pick a module from that list you want to know # more about ... # to get help about module calendar ... help("calendar") # dito for the math module help("math") # file stuff ... help("file") # down to method/function level ...:
One more helpful hint to get this thing off to a hopefully good start. How do we read a simple text file in Python? Also, what can we do with the data after we read it?
# read a text file to a string and create a list of words # use any text file you have ... textf = open('xmas.txt', 'r') str1 = textf.read() textf.close() print( "The text file as one string:" ) print( str1 ) # splits at the usual whitespaces wordlist = str1.split(None) print( "\nThe string as a list of words:" ) print( wordlist ) print( "\nThere are %d words in the list." % len(wordlist) )
Want more help about split()? At the interactive page >>> prompt enter
help("string.split")
One more function sample to show you that a function can decide internally what type of number to return. Also shows an example of try/except exception handling.
# a function to return the numeric content of a cost item # for instance $12.99 or -$123456789.01 (deficit spenders) def getVal(txt): if txt[0] == "$": # remove leading dollar sign txt = txt[1:] if txt[1] == "$": # could be -$xxx txt = txt[0] + txt[2:] while txt: # select float or integer return try: f = float(txt) i = int(f) if f == i: return i return f except TypeError: # removes possible trailing stuff txt = txt[:-1] return 0 # test the function ... print( getVal('-$123.45') )
Click on "Toggle Plain Text" so you can highlight and copy the code to your editor without the line numbers.
...
# explore the Tkinter GUI toolkit try: # for Python2 import Tkinter as tk except ImportError: # for Python3 import tkinter as tk # create a window frame frame1 = tk.Tk() # create a label label1 = tk.Label(frame1, text="Hello, world!") # pack the label into the window frame label1.pack() frame1.mainloop() # run the event-loop/program.
...
print( "The grade point average (GPA) calculator:" ) def get_list(prompt): """ loops until acceptable data or q (quit) is given returns a list of the entered data """ data_list = [] while True: sin = raw_input(prompt) # input(prompt) in Python3 if sin == 'q': return data_list try: data = float(sin) data_list.append(data) except ValueError: print( "Enter numeric data!" ) print('') gp_list = get_list("Enter grade point (q to quit): ") print( gp_list ) # test # process the list ... # calculate the average (sum of items divided by total items) gpa = sum(gp_list)/len(gp_list) print( "The grade point average is:", gpa )
Since Python2's raw_input() will not work with Python3, you can use try/except to make your program work with both versions ...
# use module datetime to show age in days # modified to work with Python2 and Python3 import datetime as dt prompt = "Enter your birthday (format = mm/dd/yyyy): " try: # Python2 bd = raw_input(prompt) except NameError: # Python3 bd = input(prompt) # split the bd string into month, day, year month, day, year = bd.split("/") # convert to format datetime.date(year, month, day)) birthday = dt.date(int(year), int(month), int(day)) # get todays date today = dt.date.today() # calculate age since birth age = (today - birthday)!
I need to write a function that can return more than one item. This is a simple example how to do it ...
# use a tuple to return multiple items from a function # a tuple is a set of values separated by commas def multiReturn(): return 3.14, "frivolous lawsuits", "Good 'N' Plenty" # show the returned tuple # notice that it is enclosed in () print( multiReturn() ) # load to a tuple of variables num, str1, str2 = multiReturn() print( num ) print( str1 ) print( str2 ) # or pick just the element at index 1, should be same as str1 # tuples start at index zero just like lists etc. print( multiReturn()[1] )
This example has not only a multiple argument return, but also allows you to call it with multiple arguments of flexible size/number ...
# explore the argument tuple designated by *args # used for cases where you don't know the number of arguments def sum_average(*args): size = len(args) sum1 = sum(args) average = sum1/float(size) # return a tuple of three arguments # args is the tuple we passed to the function return args, sum1, average # notice that the first element is the args tuple we send to the function print( sum_average(2, 5, 6, 7) ) # ((2, 5, 6, 7), 20, 5.0) # or unpack into a tuple of appropriate variables args_tuple, sum2, average = sum_average(2, 5, 6, 7) print( "sum of %s = %d" % (args_tuple, sum2) ) # sum of (2, 5, 6, 7) = 20 print( "average of %s = %0.2f" % (args_tuple, average) ) # average of (2, 5, 6, 7) = 5.00 # or just pick one return value, here value at index 1 = the sum print( "sum =", sum_average(2, 5, 6, 7)[1] ) # sum = 20
Click on "Toggle Plain Text" so you can highlight and copy the code to your editor.
The Python module pickle allows you to save objects to file as a byte stream that contains the object information. When you load the file back the object is intact. Here is a little code example ...
# use binary file modes "wb" and "rb" to make pickle # work properly with both Python2 and Python3 import pickle myList1 = [1, 2, 03, 04, 3.14, "Monty"] print( "Original list:" ) print( myList1 ) # save the list object to file file = open("list1.dat", "wb") pickle.dump(myList1, file) file.close() # load the file back into a list file = open("list1.dat", "rb") myList2 = pickle.load(file) file.close() # show that the list is still intact print( "List after pickle.dump() and pickle.load():" ) print( myList2 )
The same procedure applies to other objects like variables, tuples, sets, dictionaries and so on.
The Python module calendar is another interesting collection of functions (methods). If you ever need to show all 12 monthly calendars for the year, use this code ...
# print out a given year's monthly calendars import calendar calendar.prcal(2005)
If you just want June 2005 use ...
import calendar calendar.prmonth(2005, 6) """ result --> June 2005 Mo Tu We Th Fr Sa Su 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 """
Just for fun, ask a C++ programmer to do this in two lines of code. Now you know why Python is considered a high level language.
Here is a somewhat more complete program, asking the user for the year ...
# allowing for user input import calendar print( "Show a given year's monthly calendars ..." ) print('') # Python3 uses input() instead of raw_input() year = int(raw_input("Enter the year (eg. 2005): ")) print('') calendar.prcal(year) print('') raw_input("Press Enter to go on ...") # wait # with Pytho3 use ... #input("Press Enter to go on ...") # wait
Note, print('') prints an empty line in Python2 and Python3.
Since I have Dev-C++ on my computer I tricked it into using Python and do the calendar thing.
// needs the Python-2.4.1.DevPak installed into Dev-C++, download from: // // create project with File > New > Project... > Scripting > Python #include <iostream> #include <string> // run the Python interpreter eg. Python24.dll // this macro saves on typing! #define PY PyRun_SimpleString(input.c_str()) using namespace std; // include the Python library header extern "C" { #include <python2.4/Python.h> } int main() { // initialize Python Py_Initialize(); // optional - display Python version information cout << "Python " << Py_GetVersion() << endl << endl << endl; string input; // this module is in Python24\lib as calendar.py // could include it in the working folder if problem input = "import calendar"; PY; // print out the year's monthly calendar input = "calendar.prcal(2005)"; PY; // finish up and close Python Py_Finalize(); cin.get(); // console wait return 0; }
Since we are on the subject of modules that come with Python, there is the operating system module called simply os. Here is one thing you can use it for ...
# list all the configuration (.ini) files in C:\Windows import os fileList = [] # start with an empty list for filename in os.listdir("C:/Windows"): if filename.endswith(".ini"): fileList.append(filename) # now show the list for filename in fileList: print( filename )
There are lots of things you can do with this module. I guess you just have to type help('os') in the interactive window (the one with the >>> prompt) .
You Mac folks will have to change the folder/directory name and the extension.
We have used the replace() function before. This time we use it in a for loop to create new words. The example also gives us a look at the if conditional statement ...
# make your own words, when Q comes up we want to use Qu str1 = 'Aark' print( "Replace A in %s with other letters:" % str1 ) # go from B to Z for n in range(66, 91): ch = chr(n) if ch == 'Q': # special case Q, use Qu ch = ch + 'u' print( str1.replace('A', ch) )
A variation of the above to show off the if/else statement ...
# make your own words, here we have to avoid one # word to get past the guardians of the nation's morals str1 = 'Auck' print( "Replace A in %s with other letters:" % str1 ) # go from B to Z for n in range(66, 91): ch = chr(n) if ch == 'Q': # special case Q, use Qu ch = ch + 'u' if ch == 'F': # skip the F word continue else: print( str1.replace('A', ch) )
These little code samples are fun to experiment with.
A note for the C programmers, Python treats characters as strings. This makes life a lot simpler!
Instead of reading a file, you can read the HTML code of a web site. Of course, you have to be connected to the internet to do this ...
# if you are on the internet you can access the HTML code of a given web site # using the urlopen() method/function from the module urllib2 # tested with Python 2.5.4 import urllib2 urlStr = '' try: fileHandle = urllib2.urlopen(urlStr) str1 = fileHandle.read() fileHandle.close() print '-'*50 print 'HTML code of URL =', urlStr print '-'*50 except IOError: print 'Cannot open URL %s for reading' % urlStr str1 = 'error!' print str1
Notice that we have added the try/except exception handling to this code.
Note: Python3 uses urllib.request.urlopen() instead of urllib2.urlopen()
If you use Python3, try this code ...
# get html code of given URL # Python3 uses urllib.request.urlopen() # instead of Python2's urllib.urlopen() or urllib2.urlopen() # also urllib is a package in Python3 # tested with Python 3.1 import urllib.request fp = urllib.request.urlopen("") # Python3 does not read the html code as string # but as html code bytearray mybytes = fp.read() fp.close() # try utf8 to decode the bytearray to a string mystr = mybytes.decode("utf8") print(mystr)
If you are the curious type and want to know beforehand whether you are connected to the internet, this code might tell you ...
# are we connected to the internet? # tested with Python 2.5.4 import os def isSSL(): """ return true if there is a SSL (https) connection """ if (os.environ.get('SSL_PROTOCOL', '') != ''): return true else: return false if isSSL: print( "We have a SSL connection" ) else: print( "No SSL connection" )
Click on "Toggle Plain Text" so you can highlight and copy the code to your editor.
Do you want to impress your friends? Of course you do! Try this Python code example using the datetime module ...
# how many days old is this person? from datetime import date # a typical birthday year, month, day # or change it to your own birthday... birthday = date(1983, 12, 31) now = date.today() print( '-'*30 ) # 30 dashes print( "Today's date is", now.strftime("%d%b%Y") ) print( "Your birthday was on", birthday.strftime("%d%b%Y") ) # calculate your age age = now - birthday print( "You are", age.days, "days old" )
The datetime module is smart enough to catch erroneous dates like date(1983, 12, 32) or date(1983, 2, 29).
Notice the variation of the import statement. Here we are just importing the date method from the datetime module. This saves you from having to code:
now = datetime.date.today()
Might be good for long code where you would have to write this twenty times.
Here is another practical code ...
# calculate days till xmas from datetime import date now = date.today() # you may need to change the year later xmas = date(2005, 12, 25) tillXmas = xmas - now print( '-'*30 ) # 30 dashes print( "There are", tillXmas.days, "shopping days till xmas!" )
Calculations like this can lead to a lot of headscratching, Python does it for you without a scratch ...
# add days to a given date from datetime import date, timedelta now = date.today() delta = timedelta(days=77) addDays = now + delta print( '-'*30 ) # 30 dashes print( "Today's date is :", now.strftime("%d%b%Y") ) print( "77 days from today:", addDays.strftime("%d%b%Y") )
Impressed? I am!
This little fun with numbers program shows how range() and the for loop work together. A little trick I learned in fourth grade applied to Python.
# call it "all the same" num1 = 12345679 # the 8 is left out! # k goes from 9 to <82 in steps of 9 for k in range(9, 82, 9): print( num1 * k )
Here is another one ...
print("Bo Derek getting older:") for k in range(10, 0, -1): print(k)
I took this from a recent thread, to show you how you can use a temporary print statement to figure out what is going on ...
# create a jumbled word/string # tested with Python 2.5.4 import random # create a sequence, here a tuple, of words to choose from WORDS = ("python", "jumble", "easy", "difficult", "answer", "babysitter") # pick one word randomly from the sequence word = random.choice(WORDS) # create a variable to use later to see if the guess is correct correct = word # create a jumbled version of the word # start with an empty string to be built up in the while loop jumble = "" # word is reduced in size by one character each time through the loop # when it is empty it will be equal to None(False) and the loop stops while word: print( word, ' ', jumble ) # for test only position = random.randrange(len(word)) jumble += word[position] word = word[:position] + word[(position + 1):] print( jumble ) # now you can ask to guess the word ...
Just a little note, when you save this code, don't save it as random.py. Python will confuse this in the import statement! It will look for the module random.py in the working directory first, before it goes the \Lib directory where the proper module is located.
Strings are immutable, which means you cannot directly change an existing string, bummer! The following code would give you an error ...
str1 = 'Hello World!' str1[0] = "J" # gives TypeError: object does not support item assignment
Where there is a will, there is a way around this obstacle ...
str1 = 'Hello World!' # these statements give the intended result, since they create a new string # slicing and concatination str2 = 'J' + str1[1:] # using replace() str3 = str1.replace('H', 'J') # or change the string to a list of characters, do the operation, and join the # changed list back to a string charList = list(str1) charList[0] = 'J' str4 = "".join(charList) print( str1 ) print( str2 ) print( str3 ) print( str4 )
Along the last thought, lets have some word fun ...
# just a little word fun ... import random str1 = "Mississippi" charList = list(str1) random.shuffle(charList) str2 = "".join(charList) print( "\nString '%s' after random shuffle = '%s'" % (str1, str2) )
The last code example could be the start of a "guess the word" game.
Another recent thread was the impetus for this hint.
As you run the Python interpreter on a Python text code file (.py), the file is internally compiled to a .pyc byte code file that speeds up the interpretation process. Most of the time this is transparent to you, as the byte code file for speed sake is created in memory only.
If a Python text code .py file is imported by another Python file, a corresponding .pyc is created on disk to speed up the reuse of that particular file. Using .pyc files speeds things up saving the compilation step.
There is an additional benefit, the compiled files are not readable with a text editor. You can distribute your .pyc file instead of the .py file, this way you can hide your source code a little from folks who like to fiddle with source code.
Let's say you have a file called MyPyFile.py and want to create the compiled file MyPyFile.pyc for higher speed and/or the prevention of unauthorized changes. Write a little one line program like this:
import MyPyFile # converts MyPyFile.py to MyPyFile.pyc
Save it as CompileMyPyFile.py in the same folder as MyPyFile.py and run it. There now should be a MyPyFile.pyc file in that folder. Python.exe runs the source file or the compiled file.
Here is another way to create the compiled file ...
# create a byte code compiled python file import py_compile py_compile.compile("MyPyFile.py") # creates MyPyFile.pyc
Note: Changed code tags, looks like we lost the php tags!
Related Articles | http://www.daniweb.com/software-development/python/threads/20774/starting-python | CC-MAIN-2013-48 | refinedweb | 4,073 | 72.87 |
CDSND Connect: Direct issue
Error while executing CDSND command. (SDE0210I - Requested data set not available. Allocated to another job. )
Send physical file in SAVF format via CDSND
How to send physical file in SAVF format (Save file) from AS/400 server to other server via CDSND command?
CDSND character mapping in AS/400
Currently in our system, we are sending a physical file using CDSND to a UNIX system. In the physical file we have '[' charecter, but when this file is transferred to UNIX system this character is changed to Ã. I want to see the [ character at UNIX system, as à causing some issue at UNIX...
Questions on CDSND Command
I am sending file to LAN Folder using CDSND Command in .TXT Format. There is carriage return (New line)added at the end of extract file. I just want to send the file without carriage return. How to achieve this | http://itknowledgeexchange.techtarget.com/itanswers/tag/cdsnd/ | CC-MAIN-2015-32 | refinedweb | 151 | 66.23 |
📅 2020-Oct-06 ⬩ ✍️ Ashwin Nanjappa ⬩ 🏷️ conference, llvm ⬩ 📚 Archive
I had been meaning to attend the LLVM Developers' Meeting for a couple of years now, mostly because it happens right next door in San Jose. This year the conference went virtual and actually made it easy for me to finally attend all 3 days (Oct 6-8). Below are my notes from the talks I attended from their multiple-track agenda. This being the first time I am attending a compiler conference, let alone a LLVM one, I focused on gaining basic knowledge of the software architecture of compilers, usage of common tools and techniques in the field.
This was my first virtual conference and I was highly skeptical if it would work out. But I was pleasantly surprised how well the conference was!
_Ptr<T>,
_Array_ptr<T>and
_Nt_array_ptr<T>.
clang-tidy --list-checks: To list all currently active checks. This is not the full list of available checks.
clang-tidy --list-checks -checks=*: Lists all available checks.
clang-tidy ... -checks=-*,<your specific check>: To pick out a specific check to apply.
clang-tidy ... --fix: Not just check, but also fix the errors found.
clang-queryis an interactive tool to play around with clang C++ API to query AST and figure out the calls to match a pattern.
add_new_check.py <category> <check name>
__attribute__((noinline))and
__attribute__((cold)).
llvm.matrix.*instructions that can be used for this mapping.
llvm.matrix.column.major.load()to load matrix for MMA and
llvm.matrix.multiply()to do MMA.
*defined for multiplication of matrices and
+and
-defined for elementwise addition and subtraction of matrices.
[][]defined as element subscript operator for matrices.
@llvm.matrix.*.
I noted the following from the talks which were 5-minutes each:
import lldb) and other languages like Lua using SWIG.
*with
+and check if unit tests fail or not.
clang --analyze foobar.cpp. Can also dump to a HTML report with other options. | https://codeyarns.com/tech/2020-10-06-llvm-virtual-developers-meeting-2020.html | CC-MAIN-2021-04 | refinedweb | 323 | 58.69 |
Contributing guide
We welcome your contributions! Please see the provided steps below and never hesitate to contact us.
If you are a new user, we recommend checking out the detailed Github Guides.
Setting up a development installation¶
In order to make changes to
napari, you will need to fork the
repository.
If you are not familiar with
git, we recommend reading up on this guide.
Clone the forked repository to your local machine and change directories:
git clone cd napari
Set the
upstream remote to the base
napari repository:
git remote add upstream
Install the package in editable mode, along with all of the developer tools
pip install -r requirements.txt
We use
pre-commit to sort imports with
isort, format code with
black, and lint with
flake8 automatically prior to each commit.
To minmize test errors when submitting pull requests, please install
pre-commit
in your environment as follows:
pre-commit install
Upon committing, your code will be formatted according to our
black
configuration, which includes the settings
skip-string-normalization = true and
max-line-length = 79. To learn more,
see
black’s documentation.
Code will also be linted to enforce the stylistic and logistical rules specified
in our
flake8 configuration, which currently ignores
E203,
E501,
W503 and
C901. For information
on any specific flake8 error code, see the Flake8
Rules. You may also wish to refer to
the PEP 8 style guide.
If you wish to tell the linter to ignore a specific line use the
# noqa
comment along with the specific error code (e.g.
import sys # noqa: E402) but
please do not ignore errors lightly.
Adding icons¶
If you want to add a new icon to the app, make the icon in whatever program you
like and add it to
napari/resources/icons/. Icons must be in
.svg format.
Icons are automatically built into a Qt resource file that is imported when
napari is run. If you have changed the icons and would like to force a rebuild
of the resources, then you can either delete the autogenerated
napari/resources/_qt_resources*.py file, or you can set the
NAPARI_REBUILD_RESOURCES environmental variable to a truthy value, for
example:
export NAPARI_REBUILD_RESOURCES=1
Icons are typically used inside of one of our
stylesheet.qss files, with the
{{ folder }} variable used to expand the current theme name.
QtDeleteButton { image: url(":/themes/{{ folder }}/delete.svg"); }
Creating and testing themes¶
A theme is a set of colors used throughout napari. See, for example, the
builtin themes in
napari/utils/theme.py. To make a new theme, create a new
dict with the same keys as one of the existing themes, and
replace the values with your new colors. For example
from napari.utils.theme import get_theme, register_theme blue_theme = get_theme('dark') blue_theme.update( background='rgb(28, 31, 48)', foreground='rgb(45, 52, 71)', primary='rgb(80, 88, 108)', current='rgb(184, 112, 0)', ) register_theme('blue', blue_theme)
To test out the theme, use the
theme_sample.py file from the command line as follows:
python -m napari._qt.theme_sample
note: you may specify a theme with one additional argument on the command line:
python -m napari._qt.theme_sample dark
(providing no arguments will show all themes in
theme.py)
Translations
To make your code translatable (localizable), please use the
trans helper
provided by the napari utilities.
from napari.utils.translations import trans some_string = trans._("Localizable string")
To learn more, please see the translations guide.
Making changes¶
Create a new feature branch:
git checkout main -b your-branch-name
git will automatically detect changes to a repository.
You can view them with:
git status
Add and commit your changed files:
git add my-file-or-directory git commit -m "my message"
Tests¶
We use unit tests, integration tests, and functional tests to ensure that napari works as intended. Writing tests for new code is a critical part of keeping napari maintainable as it grows.
We have dedicated documentation on testing that we recommend you read as you’re working on your first contribution.
Help us make sure it’s you¶
Each commit you make must have a GitHub-registered email
as the
author. You can read more here.
To set it, use
git config --global user.email [email protected].
Keeping your branches up-to-date¶
Switch to the
main branch:
git checkout main
Fetch changes and update
main:
git pull upstream main --tags
This is shorthand for:
git fetch upstream main --tags git merge upstream/main
Update your other branches:
git checkout your-branch-name git merge main
Building the docs¶
From the project root:
make docs
The docs will be built at
docs/_build/html.
Most web browsers will allow you to preview HTML pages.
Try entering in your address bar.
To read more about the docs, how they’re organized, and built, read Organization of Documentation for napari.
Code of Conduct¶
napari has a Code of Conduct that should be honored by everyone who participates in the
napari community. | https://napari.org/developers/contributing.html | CC-MAIN-2022-05 | refinedweb | 828 | 62.68 |
Ticket #202 (new enhancement)
cannot roundtrip offset-aware datetime instances
Description
I'd expect that yaml.load(yaml.dump(foo) == foo for reasonable values of foo.
However, this isn't true for timezone-aware datetimes:
>>> import datetime >>> from pytz import utc >>> import yaml >>> dt = datetime.datetime(2011, 9, 1, 10, 20, 30, 405060, tzinfo=utc) >>> yaml.load(yaml.dump(dt)) == dt Traceback (most recent call last): File "<stdin>", line 1, in <module> TypeError: can't compare offset-naive and offset-aware datetimes >>> yaml.load(yaml.dump(dt)) datetime.datetime(2011, 9, 1, 10, 20, 30, 405060)
PyYAML dumps the offset correctly, but when it loads the value, it returns a naive datetime in UTC, with the offset susbtracted.
Instead, I suggest using a simple tzinfo class, such as the following (from) to represent offsets:
from datetime import timedelta, tzinfo timedelta(0)
Note that it often makes sense to handle naive datetimes (such as user input) in local times. In such cases, round-tripping a timezone-aware datetime through PyYAML — for example, dumping/loading fixtures in Django — will result in data corruption.
See also #25 and this solution to the same problem.
Change History
comment:2 Changed 4 years ago by Matt Behrens <matt@…>
I started looking at what it would take to create a patch for this and I've come up on a few hard problems.
The first thing I did was go ahead and patch construct_yaml_timestamp so that if a + or -HH:MM timezone was specified, a tzinfo instance was created with that offset, much like was suggested in this ticket's description.
When I went to add UTC support for Z timezones, I started looking more critically at the implementation of the spec itself. Specifically, according to my reading, any timestamp that does not have a timezone—even those with no time specified at all—should be UTC. Thus, because you can't localize a date instance, and because date instances don't appear to make any assertions as to time-of-day in contrast to the spec which says missing time should be read as 00:00:00Z, construct_yaml_timestamp should never return a date instance for a date-only timestamp value, but instead a datetime with hour 0, minute 0, and tzinfo UTC.
I do fear that such changes will break a lot of code that are used to receiving either date instances or naïve datetime instances, though.
My current work on this problem as a starting point for discussion: Keep in mind it does break tests right now, largely because date and datetime instances are incomparable as well as naïve and offset-aware datetime instances.
comment:3 Changed 4 years ago by Matt Behrens <matt@…>
- Cc matt@… added
- Summary changed from PyYAML to cannot roundtrip offset-aware datetime instances
comment:4 Changed 4 years ago by Matt Behrens <matt@…>
I have a working implementation here:
The new behavior can be switched on or off with a keyword argument to load et al.
I do not have tests for the new behavior yet. I will probably write a new test case for them.
This bug actually affects users of Django: | http://pyyaml.org/ticket/202 | CC-MAIN-2017-22 | refinedweb | 524 | 55.58 |
You have two options.
Create a base class
You can create a base class that inherits System.Web.UI.Page and inherit this class in all your pages:
public class BasePage : System.Web.UI.Page
{
public string ImagePath { get; set; }
}
And then inherit this class in your pages:
public partial class Default2 : BasePage
{
....
}
Create an interface
You can create an interface like this:
public interface Interface1
{
string ImagePath { get; set; }
}
And then inherit this interface on all your pages:
public partial class Default2 : System.Web.UI.Page, Interface1
{
public string ImagePath { get; set; }
}
As you can see, the first option (base class) has some advantages over the interface option. You have to define and implement your property only once when using a base class. When using interfaces you have to implement the property on every page too.
This is because an interface is only used to define what properties and function there are on an object, not how they work. While a base class can already implement the properties and functions.
Total Post:48Points:336
ASP.Net C#
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I am using aspx forms. What we do is that we declare property like for every form. Code is at the end
So I was thinking that if we could have a base class that have all the stuff like this but as the form already inherit the Page class we don't have multiple inheritance in C# so here can we use interface to achieve this I am new to oops please let me know it is possible or not.
public partial class Default2 : System.Web.UI.Page
{
public string ImagePath { get; set; }
} | https://www.mindstick.com/forum/12751/how-to-abstract-a-property-in-asp-dot-net-pages | CC-MAIN-2017-26 | refinedweb | 278 | 71.85 |
Db2 for z/OS delivered native REST services support in the end of 2016. I wrote 2 white paper on how to create a DB2 REST service and how to consume this service from a mobile device (). Later I wrote a blog on how to consume a Db2 REST service from a node.js application. I start getting enquiries on how to do the same thing from a python application. In this blog, I am going to share my experience in implementing and executing a python application in a Window machine to invoke a Db2 for z/OS REST service.
I have download Python 3.7.0 to C:\Python\Python37-32 directory
To verify the version you download
C:\Python\Python37-32>py --version
Python 3.7.0
In Part 1 of my whitepaper, we have created a Db2 REST service for the following SQL statement
SELECT SUBSTR(STRING,1,60) as STRING from SYSIBM.SYSXMLSTRINGS WHERE STRINGID= ?
with following url:
Example to invoke the service:
{
"P1": 1006
}
{ 'ResultSet Output': [ { STRING: 'space ' } ],
StatusCode: 200,
StatusDescription: 'Execution Successful' }
You can start with Python interactive shell, and then put everything in a standalone Python application. Or you can start with a standalone application right away. Both options are described below.
To start a Python interactive shell:
C:\Python\Python37-32>python
Once you are inside python interactive shell, below are what I have entered to invoke the Db2 REST service. You need to customize the following(like userid, pw, etc.) according to your setting. Print statement output are highlighted in yellow below.
>>>())
{'ResultSet Output': [{'STRING': 'space '}], 'StatusCode': 200, 'StatusDescription': 'Execution Successful'}
>>> print(resp.json()["ResultSet Output"])
[{'STRING': 'space '}]
>>> print(resp.json()["ResultSet Output"][0].get('STRING'))
space
The code/commands are self-explained. We first
Under C:\Python\Python37-32 directory, I have created an application called TestREST.py.
Below is the content of TestREST.py, which is same as what I used in the interactive shell above.())
print(resp.json()["ResultSet Output"])
print(resp.json()["ResultSet Output"][0].get('STRING'))
C:\Python\Python37-32>python TestREST.py
There are 3 print statement outputs:
{'ResultSet Output': [{'STRING': 'space '}], 'StatusCode': 200, 'StatusDescription': 'Execution Successful'}
[{'STRING': 'space '}]
As you can see, it is very simple to consume a Db2 REST service in a python application. With Python built-in libraries, sending a HTTP request, parsing JSON response is just a few lines of code.
With many years' development of Db2 for z/OS, it provides a lot of wonderful features in each release. Among these features, some of them are extremely useful but less “well-known”. Pattern matching using regular expression is one of these hidden gems. And I still get customers asking me about this!!
In the first part of the following article, I will give a short introduction on this topic.
Pattern Matching using Regular Expression and Utilizing Services outside Db2 for z/OS
In the recent customers’ conference calls, a lot of customers are confused about Db2 for z/OS JSON capability and Native REST services. They think they are the same thing. In fact, they are completely different. In the following article, I will describe the difference and share the questions I have been asked many times. A node.js application is included as example to invoke a Db2 native REST service.
Db2 for z/OS JSON SQL APIs and Native REST Services
When Db2 first delivered its native REST support back in late 2016, it only allowed the REST services to be created or dropped via REST calls. Application developers who are already familiar with REST calls loves this. For those who don’t want to write an application to create/drop services, they can use a web browser with REST client installed to achieve the same purpose. However, this creates some challenges for those who don’t write application very often or for the folks who want to create the same services on multiple Db2 subsystems.
With PI86867(V11) and PI86868(V12), user can create and drop a native REST service via BIND SERVICE and FREE SERVICE respectively.
See my other article or IBM Knowledge Center for more details.
Below is the syntax for BIND SERVICE:
BIND SERVICE(<collection-id>) NAME(<service-name>)
SQLDDNAME(<ddname>)
SQLENCODING( ASCII | EBCDIC | UNICODE | <ccsid>)
DESCRIPTION (<description-string>)
<Additional BIND options>
Suppose we want to create a Db2 native REST service for the following SQL statement:
Please note SYSIBM.SYSXMLSTRINGS is a catalog table, so you don’t need to create any user table to make this example work.
1. Put above SQL statement into a HFS file or dataset. We use HFS file as example in this blog, you can also use PDS. See Resources section for more details.
Suppose I have put it in a HFS file (sql.txt) in /tmp directory
$ cat /tmp/sql.txt
2. Create a job with following content (you may need to customize the job according to your environment)
//BIND EXEC TSOBATCH,DB2LEV=DB2A,COND=(4,LT)
//SQLDDNAM DD PATH='/tmp/sql.txt',
// PATHOPTS=ORDONLY,
// RECFM=VB,LRECL=32756,BLKSIZE=32760
//SYSTSIN DD *
BIND SERVICE(SYSIBMSERVICE) NAME("selectSYSXMLStrings") -
SQLDDNAME(SQLDDNAM) DESCRIPTION('test')
Please note:
Below is the syntax for FREE SERVICE
FREE SERVICE(<collection-id>.<service-name>)
To free the service we created above:
FREE SERVICE(SYSIBMSERVICE."selectSYSXMLStrings")
SQLDDNAME bind option
The LISTAGG function is used to aggregate a set of string values within a group into one string. It is the most important function in Db2 12 for z/OS continuous delivery function level 501. In the following article, we will introduce this function with working examples, and then compare it with a similar aggregate function, XMLAGG, inside Db2 for z/OS.
Python is one of the most commonly used programming language. Its interactive mode is ideal for prototype development and ad-hoc tasks. There is also a development GUI. Both are free to download or use under open source license. In this blog, I am going to show you how to use Python to connect to DB2 11 for z/OS and perform some basic database operations.
(Updated on May 20, 2019: if you are interested in invoking a Db2 REST service from a Python 3 application, read my other blog)
* I highly recommend to install Python 2.7.9 or higher (but not 3.X). If you have installed Python 2 >=2.7.9, you already have pip and setuptools (that is used to install other modules/packages)
I have download Python 2.7.13 for my Windows machine. I took all default options, only change the install location to C:\Python\Python27.
To verify your installation,
C:\Python\Python27>python –version
If you have installed Python 2.7.9 or higher, setuptools like easy_install, pip are located in C:\Python\Python27\Scripts
C:\Python\Python27>.\Scripts\easy_install ibm_db
ibm_db (egg) will be installed in C:\Python\Python27\Lib\site-packages\ibm_db-2.0.7-py2.7.egg
From the job output, you can tell the package installed also include IBM ODBC and CLI Driver from IBM.
In addition to ibm_db, you can also download/install ibm_db_dbi, ibm_db_sa adapter for SQLAlchemy, ibm_db_django adapter for Django. See Resource section for more details. For the exercise in this blog, we only need ibm_db.
If the DB2 for z/OS server you planned to connect is not activated yet, you can run db2connectactivate utility to activate the server (see Resources section). Another option is copy the DB2 Connect license to installation_path/license directory.
If your server is not activated yet and you don’t have a DB2 Connect license in the license directory, you will get the following error when you try to connect to DB2.
Exception: [IBM][CLI Driver] SQL1598N An attempt to connect to the database ser
SQLCODE=-1598ause of a licensing problem. SQLSTATE=42968
C:\Python\Python27>set PYTHONPATH=C:\Python\Python27\Lib\site-packages\ibm_db-2.0.7-py2.7.egg
(You may need to customize this according to the “egg” version you have installed).
We are going to use Python interactive shell to SELECT from a catalog table, SYSIBM.SYSXMLSTRINGS table. SYSIBM.SYSXMLSTRINGS contains a mapping of string id (4 bytes integer) to an actual string.
In the python install directory, type python to launch the interactive shell.
C:\Python\Python27>python
Python 2.7.13 (v2.7.13:a06454b1afa1, Dec 17 2016, 20:42:59) [MSC v.1500 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import ibm_db
>>> conn = ibm_db.connect("DATABASE=<database>;HOSTNAME=<host.co)
...
Inside ibm_db.connect(), you need to customize the parameters according to your DB2 setting. The statements above are easy to understand:
Output may be different from different DB2. Below is what I get from my DB2:
The STRING ID is : 1001
The actual string is : product
The STRING ID is : 1002
The actual string is : description
The STRING ID is : 1003
The actual string is : name
Type exit() to exit the interactive shell.
We can create a Python program containing the statements that we have tested above (using interactive shell). Suppose we want to create a Python program called testDBz.py.
The content of testDBz.py is:
import ibm_db
conn = ibm_db.connect("DATABASE=<database>;HOSTNAME=<host)
To execute:
C:\Python\Python27\python testDBz.py
In this blog, I have shown you how to set up your environment to implement and execute a simple Python program to connect to DB2 for z/OS and do some simple database operations. There are also a lot of other Python database features that you can explore. In short, there are a lot of options in implementing modern applications to connect to DB2 for z/OS, not only COBOL or JAVA!
DB2 for z/OS delivered native REST services support in the end of 2016. I wrote 2 white paper on how to create a DB2 REST service and how to consume this service from a mobile device. I start getting enquiries on how to consume a DB2 REST service from a node.js application. In this blog, I am going to share my experience in implementing a node.js application to invoke a DB2 REST service.
Update on May 20, 2019: Read my other blog if you are interested in doing the same thing in a Python application.
C:\NodeApp>npm install node-rest-client
Output:
[email protected] C:\NodeApp
`-- [email protected]
+-- [email protected]
| `-- [email protected]
+-- [email protected]
| `-- [email protected]
| `-- [email protected]
`-- [email protected]
+-- [email protected]
`-- [email protected]
`-- [email protected]
In Part 1 of my whitepaper, we have created a DB2 REST service for the following SQL statement
with following url:
Under C:\NodeApp> directory, I have created an application called nodeREST.js. The code itself is self-explained.
Below is the content of nodeREST.js:
var Client = require('node-rest-client').Client;
var client = new Client();
//create a base64 encoding of userid:password
//need to fill out with actual userid and password
var userpw = "userid:password";
var buffer = new Buffer(userpw);
var userPwBase64 = buffer.toString('base64');
// set content-type header and data as json in args parameter
var args = {
data: { "P1": 1006 },
headers: { "Content-Type": "application/json",
"Authorization": "Basic " + userPwBase64,
"Accept": "application/json" }
};
client.post("", args, function (data, response) {
// parsed response body as js object
console.log(data);
var ResultSetOutput = data["ResultSet Output"];
var description = ResultSetOutput[0].STRING;
console.log(description);
// raw response
//console.log(response);
});
C:\NodeApp>node nodeREST.js
{ 'ResultSet Output': [ { STRING: 'space
' } ],
As you can see, it is very simple to consume a DB2 REST service in a node.js application. With REST client for Node.js, sending a HTTP request, parsing JSON response is just a few lines of code.
Node.js allows us to manipulate JSON data in DB2 for z/OS easily. In this blog, I am going to share my experience in writing node.js applications to access the data stored in DB2 for z/OS. We start from download and installation of Node, testing connection to DB2 for z/OS, retrieving data from catalog table, and then manipulation of JSON data in DB2 for z/OS.
I have downloaded Windows(x64) node-v6.9.2-x64.msi (this will install NPM (tool to manage Node modules) as well).
Take default options.
By default, the install directory is: C:\Program Files\nodejs\
C:\Users\IBM_ADMIN>node -v
v6.9.2
C:\Users\IBM_ADMIN>npm -v
3.10.9
C:\NodeApp>npm install ibm_db
This will create C:\NodeApp\node_modules directory and install ibm_db under that directory
(under "Quick Example" section) and save the source in TestDB2Connection.js.
As you can see the source below, we use DB2 driver to connect to DB2 for z/OS and then use conn.query() to issue a SELECT statement. For other APIs, see “Database APIs” section under
var ibmdb = require('ibm_db');
ibmdb.open("DATABASE=<dbname>;HOSTNAME=<myhost>;UID=db2user;PWD=password;PORT=<dbport>;PROTOCOL=TCPIP", function (err,conn) {
if (err) return console.log(err);
conn.query('select 1 from sysibm.sysdummy1', function (err, data) {
if (err) console.log(err);
else console.log(data);
conn.close(function () {
console.log('done');
});
});
});
C:\NodeApp>node TestDB2Connection.js
For a successful run, you should see the output similar to the following
[ { '1': 1 } ]
done
Troubleshooting : If you see an error relate to package.json, something like:
Error: Cannot find module ‘ibm_db’
….
You can resolve this copying C:\NodeApp\node_modules\ibm_db\package.json to C:\NodeApp
Below is the content of TestDB2ZserverosSysXML.js:
ibmdb.open("DATABASE=<dbname>;HOSTNAME=<myhost>;UID=db2user;PWD=password;PORT=<dbport>;PROTOCOL=TCPIP",
function(err,conn) {
if (err) return console.log(err);
conn.query('select stringid, substr(string, 1, 60) as string from sysibm.sysxmlstrings fetch first 5 rows only',
function (err, rows) {
if (err) console.log(err);
else
{ console.log(rows);
//loop through the rows from the resultset
for (var i=0; i<rows.length; i++)
{
console.log(rows[i].STRINGID, rows[i].STRING.trim());
}
}
conn.close(function () {
console.log('done');
});
});
});
From the above source code, we first SELECT first 5 rows from sysibm.sysxmlstrings, which is a catalog table that contain the mapping between a stringid (integer) to a string (varchar). The results are in rows (array). We display the whole resultset using console.log(rows). Then, we iterate through resultset (rows)and print out the stringed and string column in each row of the resultset.
Execute the program:
C:\NodeApp>node TestDB2ZserverosSysXML.js
[ { STRINGID: 1001,
STRING: 'product ' },
{ STRINGID: 1002,
STRING: 'description ' },
{ STRINGID: 1003,
STRING: 'name ' },
{ STRINGID: 1004,
STRING: 'detail ' },
{ STRINGID: 1005,
STRING: 'a ' } ]
1001 'product'
1002 'description'
1003 'name'
1004 'detail'
1005 'a'
Done
(note: depends on value in your sysibm.sysxmlstrings catalog table, you may see different output)
JSON data is stored inside DB2 as BSON format in BLOB column, so during INSERT, we need to call JSON2BSON UDF to convert the data in text format to BSON format.
DROP TABLE IOD03TABLE#
CREATE TABLE IOD03TABLE (ID INT, JSONCOL BLOB)#
INSERT INTO IOD03TABLE VALUES(1, SYSTOOLS.JSON2BSON(
'{
"PO": {
"@id": 123,
"@orderDate": "2013-11-18",
"customer": { "@cid": 999 },
"items": {
"item": [
{
"@partNum": "872-AA",
"productName": "Lawnmower",
"quantity": 1,
"USPrice": 149.99,
"shipDate": "2013-11-20"
},
"@partNum": "945-ZG",
"productName": "Sapphire Bracelet",
"quantity": 2,
"USPrice": 178.99,
"comment": "Not shipped"
}
]
}
}
}'))#
Below is the content of TestDB2Zserveros_json2.js. From the source below, we extract PO.@orderData using DB2 for z/OS UDF JSON_VAL function. This function allows us to extract a field (passed in as 2nd parameter) from a JSON document (1st parameter), if found, convert to the SQL type specified in the 3rd parameter. See Resources section for more details on this function. As usual, we need to escape the single quote (') inside the SQL statement.
ibmdb.open("DATABASE=<dbname>;HOSTNAME=<myhost>;UID=db2user;PWD=password;PORT=<dbport>;PROTOCOL=TCPIP", function
(err,conn) {
conn.query('select JSON_VAL(JSONCOL, \'PO.@orderDate\', \'s:20\') as OrderDate from IOD03TABLE', function (err, data) {
To execute the program:
C:\NodeApp>node TestDB2Zserveros_json2.js
[ { ORDERDATE: '2013-11-18' } ]
DB2 for z/OS also provide a UDF JSON_TABLE to extract the JSON array entries. As you may recall, PO.items.item is an array. So, the output of JSON_TABLE function is a table with 2 entries, each contains one entry of PO.items.item. We then use JSON_VAL function to extract individual fields from these 2 entries. You can find more details about JSON_TABLE function in the Resources section.
Below is content in TestDB2Zserveros_json3.js.
conn.query(
'SELECT JSON_VAL(SYSTOOLS.JSON2BSON(X.VALUE), \'@partNum\', \'s:10\') as @partNum, '
+ ' JSON_VAL(SYSTOOLS.JSON2BSON(X.VALUE), \'productName\', \'s:20\') as productName, '
+ ' JSON_VAL(SYSTOOLS.JSON2BSON(X.VALUE), \'quantity\', \'i\') as quantity, '
+ ' JSON_VAL(SYSTOOLS.JSON2BSON(X.VALUE), \'USPrice\', \'f\') as USPrice, '
+ ' JSON_VAL(SYSTOOLS.JSON2BSON(X.VALUE), \'shipDate\', \'s:20\') as shipDate '
+ 'FROM IOD03TABLE, '
+ 'TABLE(SYSTOOLS.JSON_TABLE(JSONCOL, \'PO.items.item\', \'s:200\')) X', function (err, data) {
To Execute:
C:\NodeApp>node TestDB2Zserveros_json3.js
[ { '@PARTNUM': '872-AA',
PRODUCTNAME: 'Lawnmower',
QUANTITY: 1,
USPRICE: 149.99,
SHIPDATE: '2013-11-20' },
{ '@PARTNUM': '945-ZG',
PRODUCTNAME: 'Sapphire Bracelet',
QUANTITY: 2,
USPRICE: 178.99,
SHIPDATE: null } ]
In TestDB2Zserveros_json4.js below, we SELECT the whole JSON document from DB2 first and then let the application to manipulate the JSON data. JSON data is stored inside DB2 as BSON format, so we need to call BSON2JSON UDF to convert the data in BSON format back to JSON text format.
JSON.parse()is required to convert the JSON in string format to a JSON object.
ibmdb.open("DATABASE=<dbname>;HOSTNAME=<myhost>;UID=db2user;PWD=password;PORT=<dbport>;PROTOCOL=TCPIP",
function (err,conn)
{
if (err) return console.log(err);
conn.query(
'select SYSTOOLS.BSON2JSON(JSONCOL) as JSONDOC from IOD03TABLE', function (err, rows) {
if (err) console.log(err);
else
{
//loop through the rows from the resultset
for (var i=0; i<rows.length; i++)
{
var jsondoc = JSON.parse(rows[i].JSONDOC);
var itemArray = jsondoc.PO.items.item;
for (var j=0; j<itemArray.length; j++)
console.log(itemArray[j]['@partNum'],
itemArray[j].productName,
itemArray[j].quantity,
itemArray[j].USPrice,
itemArray[j].shipDate);
}
}
C:\NodeApp>node TestDB2Zserveros_json4.js
872-AA Lawnmower 1 149.99 2013-11-20
945-ZG Sapphire Bracelet 2 178.99 undefined
In this blog, we have discussed how to install node.js and how to implement (and test) a DB2 for z/OS node.js application. Obviously, JSON support in DB2 for z/OS and node.js are complementary technologies. After reading this blog, I hope you will start writing your own node.js application to access the data in DB2 for z/OS.
This is Part 2 of blog to do machine learning using DB2 for z/OS data and Spark machine learning feature. In Part 1, we used VectorAssembler to create features as input to our model. In Part 2, we will use R formula.
Spark RFormula selects columns mentioned by an R model formula. See for details.
If you have not done so, please read Part 1 for background, pre-requisite, and general steps.
The process for using R Formula is basically same as those mentioned in Part 1. I will call out the difference and additional steps.
import org.apache.spark.ml.feature.RFormula
//use R formula
val formula = new RFormula().setFormula("drugLabel ~ AGE + GENDER + BP_TOP + CHOLESTEROL_RATIO + SODIUM + POTASSIUM").setFeaturesCol("features").setLabelCol("drugLabel")
To predict drug from age, gender, blood pressure, cholesterol ratio, sodium, and potassium, we can use a formula like following.
drugLabel ~ AGE + GENDER + BP_TOP + CHOLESTEROL_RATIO + SODIUM + POTASSIUM
Spark also support other operators, see url above for details.
RFormula produces a vector column of features. String input columns will be one-hot encoded. This is the reason that we don’t need to call StringIndexer explicitly.
// Chain indexers and tree in a Pipeline.
val pipeline = new Pipeline().setStages(Array(labelIndexer, formula, dt, labelConverter))
If you run through the steps in Part 1, replace those with steps A & B above. You may get the following predictions (on test data)
predictions.select("DRUG", "predictedLabel", "drugLabel", "features").show()
+-----+--------------+---------+--------------------+
| DRUG|predictedLabel|drugLabel| features|
|drugX| drugX| 2.0|[22.0,0.0,115.0,4...|
|drugC| drugC| 1.0|[47.0,1.0,90.0,4....|
|drugY| drugY| 0.0|[49.0,0.0,119.0,4...|
As you may recall, DRUG column is the original column from DB2 while predictedLabel column is what predicted by the model (on test data).
// Select (prediction, true label) and compute test error.
val evaluator = new MulticlassClassificationEvaluator().setLabelCol("drugLabel").setPredictionCol("prediction").setMetricName("accuracy")
val accuracy = evaluator.evaluate(predictions)
accuracy: Double = 1.0
println("Test Error = " + (1.0 - accuracy))
Test Error = 0.0
Again, a very good result.
After reading Part 1 and 2 of this blog, I hope you have some basic understanding on doing machine learning on DB2 for z/OS data. One challenge is to decide which algorithm to use. Linear Regression may be good to predict sales while Decision Tree may be used to predict loan approval. Algorithm selection depends on data and scenario and that probably require collaboration between software engineers and data scientists.
Machine learning is getting popular in the recent years. With most enterprises data are stored in DB2 for z/OS, we will show you how to do machine learning using DB2 for z/OS data and Spark machine learning feature. With an easy to follow example, we will describe how to build a model, train it, test it, and save it using Scala. In Part 1, we will use VectorAssembler to create features as input to our model. In Part 2, we will use R formula.
(Note: around 3 months after this blog is published, IBM announced "IBM Machine Learning for z/OS ", which allow you to create, deploy, and manage models with a GUI. See this link for more details.)
Suppose we have a group of people with different age, gender, blood pressure (top value), cholesterol ratio, sodium level, potassium level, and the drug they take. We want to build a model to predict the drug (drugY, drugC, or drugX) they take.
+---+------+------+------------------+----------+----------+-----+
|AGE|GENDER|BP_TOP| CHOLESTEROL_RATIO| SODIUM| POTASSIUM| DRUG|
| 23| F| 139.0| 5.1| 0.793| 0.031|drugY|
| 47| M| 90.0| 5.5| 0.739| 0.056|drugC|
| 47| M| 90.0| 4.9| 0.697| 0.069|drugC|
| 28| F| 120.0| 4.8| 0.564| 0.072|drugX|
| 61| F| 90.0| 5.2| 0.559| 0.031|drugY|
| 22| F| 115.0| 4.3| 0.677| 0.079|drugX|
| 49| F| 119.0| 4.3| 0.790| 0.049|drugY|
| 41| M| 90.0| 4.8| 0.767| 0.069|drugC|
| 60| M| 120.0| 4.7| 0.777| 0.051|drugY|
| 43| M| 90.0| 2.2| 0.526| 0.027|drugY|
For Step 2 to 6, we are following the steps in
You can use your favorable tool (like SPUFI, TEP3, Data Studio, CLP…etc.) to create and populate the table.
Below is the table DDL and SQL statements (note: I am using # as SQL terminator below).
drop table t1#
create table t1(age int, gender char(1), BP_top double, cholesterol_ratio double, sodium double, potassium double, drug varchar(5))#
insert into t1 values(23, 'F', 139, 5.1, 0.793, 0.031, 'drugY')#
insert into t1 values(47, 'M', 90, 5.5, 0.739, 0.056, 'drugC')#
insert into t1 values(47, 'M', 90, 4.9, 0.697, 0.069, 'drugC')#
insert into t1 values(28, 'F', 120, 4.8, 0.564, 0.072, 'drugX')#
insert into t1 values(61, 'F', 90, 5.2, 0.559, 0.031, 'drugY')#
insert into t1 values(22, 'F', 115, 4.3, 0.677, 0.079, 'drugX')#
insert into t1 values(49, 'F', 119, 4.3, 0.790, 0.049, 'drugY')#
insert into t1 values(41, 'M', 90, 4.8, 0.767, 0.069, 'drugC')#
insert into t1 values(60, 'M', 120, 4.7, 0.777, 0.051, 'drugY')#
insert into t1 values(43, 'M', 90, 2.2, 0.526, 0.027, 'drugY')#
Set the following environment (you may to customize this according to your environment)
Set HADOOP_HOME=C:\Hadoop
set SPARKBIN=C:\Spark210\spark-2.1.0-bin-hadoop2.7\bin
SET PATH=C:\Program Files\IBM\Java70\bin;%SPARKBIN%;%PATH%
c. Launch Spark scala shell as follows (after customizing the following to point to exact location of jcc jars)
C:\Spark210\spark-2.1.0-bin-hadoop2.7\bin\spark-shell.cmd --driver-class-path C:\jcc_home\jccbuilds\jcc411\db2jcc4.jar;C:\jcc_home\jccbuilds\jcc411\db2jcc_license_cisuz.jar
Trouble shooting: if you are getting a NullPointerException, you can correct it according to
For a successful launch, you should see something like below:
Welcome to
____ __
/ __/__ ___ _____/ /__
_\ \/ _ \/ _ `/ __/ '_/
/___/ .__/\_,_/_/ /_/\_\ version 2.1.0
/_/
Using Scala version 2.11.8 (IBM J9 VM, Java 1.7.0)
Type in expressions to have them evaluated.
Type :help for more information.
scala>
import org.apache.spark.ml.classification.DecisionTreeClassifier
import org.apache.spark.ml.feature.{IndexToString, StringIndexer, VectorIndexer, VectorAssembler,OneHotEncoder,SQLTransformer}
import org.apache.spark.ml.{Pipeline, PipelineModel}
import org.apache.spark.ml.evaluation.MulticlassClassificationEvaluator
import org.apache.spark.ml.classification.DecisionTreeClassificationModel
import org.apache.spark.sql.SparkSession
val spark = SparkSession.builder().appName("JaneMLExample").getOrCreate()
val DB2Data = spark.read.format("jdbc").options(Map("url" -> "jdbc:db2://hostname:port/location:currentSchema=schema;user=user;password=password;","driver" -> "com.ibm.db2.jcc.DB2Driver", "dbtable" -> "SYSADM.T1")).load()
Since we want to predict the drug from other attributes, DRUG column of string datatype is the output of our model. For computation, we need to change the string value (drugX, drugY, drugC) of DRUG column into double (drugLabel) using StringIndexer.
// Index labels, adding metadata to the label column.
// Fit on whole dataset to include all labels in index.
val labelIndexer = new StringIndexer().setInputCol("DRUG").setOutputCol("drugLabel").fit(DB2Data)
Similarly, we need to convert our input GENDER of char(1) to double
val genderIndexer = new StringIndexer().setInputCol("GENDER").setOutputCol("genderIndex")
val genderEncoder = new OneHotEncoder().setInputCol("genderIndex").setOutputCol("genderVec")
val assembler = new VectorAssembler().setInputCols(Array("AGE", "genderVec", "BP_TOP", "CHOLESTEROL_RATIO", "SODIUM", "POTASSIUM")).setOutputCol("features")
val Array(trainingData, testData) = DB2Data.randomSplit(Array(0.7, 0.3))
There are a lot of machine learning algorithms provided by Spark (). In this example, since we are going to predict the drug based on a person’s gender, age, blood pressure, etc., we choose decision tree.
The inputs to DecisionTreeClassifier() are passed in through setLabelCol() and setFeaturesCol(), that is drugLabel from Step 3 a) and features from Step3 c) above respectively.
val dt = new DecisionTreeClassifier().setLabelCol("drugLabel").setFeaturesCol("features")
The default output columns are prediction, rawPrediction, and probability.
val labelConverter = new IndexToString().setInputCol("prediction").setOutputCol("predictedLabel").setLabels(labelIndexer.labels)
val pipeline = new Pipeline().setStages(Array(labelIndexer, genderIndexer, genderEncoder, assembler, dt, labelConverter))
val model = pipeline.fit(trainingData)
val predictions = model.transform(testData)
DRUG column is the original column in the table, while predictedLabel is the column predicted by our model
|drugC| drugC| 1.0|[47.0,1.0,90.0,4....|
|drugY| drugY| 0.0|[49.0,0.0,119.0,4...|
To see all the columns:
predictions.show(false)
+---+------+------+------------------+------------------+--------------------+--
---+---------+-----------+-------------+----------------------------------------
--------------------+-------------+-------------+----------+--------------+
|AGE|GENDER|BP_TOP|CHOLESTEROL_RATIO |SODIUM |POTASSIUM |DR
UG |drugLabel|genderIndex|genderVec |features
|rawPrediction|probability |prediction|predictedLabel|
|22 |F |115.0 |4.3 |0.6769999999999999|0.079 |dr
ugX|2.0 |1.0 |(1,[],[]) |[22.0,0.0,115.0,4.3,0.6769999999999999,0
.079] |[0.0,0.0,1.0]|[0.0,0.0,1.0]|2.0 |drugX |
|47 |M |90.0 |4.8999999999999995|0.697 |0.069 |dr
ugC|1.0 |0.0 |(1,[0],[1.0])|[47.0,1.0,90.0,4.8999999999999995,0.697,
0.069] |[0.0,2.0,0.0]|[0.0,1.0,0.0]|1.0 |drugC |
|49 |F |119.0 |4.3 |0.7899999999999999|0.048999999999999995|dr
ugY|0.0 |1.0 |(1,[],[]) |[49.0,0.0,119.0,4.3,0.7899999999999999,0
.048999999999999995]|[4.0,0.0,0.0]|[1.0,0.0,0.0]|0.0 |drugY |
As you can see, we are getting a very good result.
model.write.overwrite().save("C:/Jane/Work/DB2/socialMedia/machineLearning/DB2Model1")
(note: if you are using Spark 1.6.2, above statement will NOT work)
val sameModel = PipelineModel.load("C:/Jane/Work/DB2/socialMedia/machineLearning/DB2Model1")
val predictionAgain = sameModel.transform(testData)
predictionAgain.select("DRUG", "predictedLabel", "drugLabel", "features").show()
|drugX| drugX| 2.0|[22.0,0.0,115.0,4...|
|drugC| drugC| 1.0|[47.0,1.0,90.0,4....|
|drugY| drugY| 0.0|[49.0,0.0,119.0,4...|
In this blog, we have discussed how to do machine learning on DB2 for z/OS data using Spark machine learning capability. We passed inputs using VectorAssembler and a Decision Tree algorithm to build/train/test our model. In Part 2, we are going to use RFormula.
Applications
Jane Man
IBM Senior Software Engineer
Clement Leung
IBM Software Engineer
Have you ever thought about building a DB2 for z/OS application that leverage cognitive APIs provided by Watson? In this article, I am going to show you how to do so.
At the time of writing this article, there is a 30-day free trial (subject to change).
It is highly recommended you read my other blog to get some basic idea on converting JSON data to relational format:
Watson provides a lot of APIs to build cognitive applications. Some APIs are targeting for languages, vision, speech, etc. The Tone Analyzer we used in this article uses linguistic analysis to detect emotions, social tendencies, and writing style. Input can be plain text or JSON and output is in JSON format. With JSON support in DB2 for z/OS, we can utilize the result from Tone Analyzer.
HTTPGETCLOB is a DB2 for z/OS UDF that allow us to send a request to a specified URL through an HTTP GET request. It takes two parameters: URL and optional http header. Output is a CLOB (5M). There are other similar UDFs, like HTTPGETBLOB, etc. See Resources section for details.
Suppose we want Watson Tone Analyzer to analyze the following text:
'I thought I can sleep in this session, but that crazy speaker keep asking us questions. Now she is asking us to read this long text and tell her what tone it is. How do I know? Ask a machine to do this’
Below is the SQL statement we need:
WITH Authorization AS (
SELECT DB2XML.BASE64ENCODE(CAST('<userid>:<password>' AS VARCHAR(64) CCSID 1208)) AS Authorization_Identity
FROM SYSIBM.SYSDUMMY1
))))
FROM Authorization
In query 1:
Output of Query 1 (truncated – reformat for readability) :
"document_tone": {
"tone_categories": [{
"tones": [{
"score": 0.206372,
"tone_id": "anger",
"tone_name": "Anger"
}, {
"score": 0.364932,
"tone_id": "disgust",
"tone_name": "Disgust"
"score": 0.451429,
"tone_id": "fear",
"tone_name": "Fear"
"score": 0.097665,
"tone_id": "joy",
"tone_name": "Joy"
"score": 0.439061,
"tone_id": "sadness",
"tone_name": "Sadness"
}]…
Assume we are interested in 'document_tone.tone_categories.tones', which is an array structure. We need to use JSON_TABLE function inside DB2 for z/OS to extract data in array structure.
Query 1 can be modified to achieve this. See Query 2 below.
SELECT DB2XML.BASE64ENCODE(CAST(‘<userid>:<password>' AS VARCHAR(64) CCSID
1208)) AS Authorization_Identity
FROM SYSIBM.SYSDUMMY1
),
TONETABLE AS())) TONERESULT
FROM Authorization)
JSON_VAL(SYSTOOLS.JSON2BSON(X.VALUE), 'score', 'f') as score,
JSON_VAL(SYSTOOLS.JSON2BSON(X.VALUE), 'tone_name', 's:20') as tone
from TONETABLE, TABLE(SYSTOOLS.JSON_TABLE(SYSTOOLS.JSON2BSON(TONERESULT), 'document_tone.tone_categories.tones', 's:200')) X
order by score DESC
Query 2 is very similar to Query 1. The last part highlighted in red is the main difference.
In Query 2,
Output for Query 2:
SCORE TONE
0.99 Extraversion
0.987 Emotional Range
0.97 Agreeableness
0.97 Analytical
0.699 Tentative
0.451429 Fear
0.439061 Sadness
0.364932 Disgust
0.206372 Anger
0.097665 Joy
0.007 Openness
0.004 Conscientiousness
0.0 Confident
13 record(s) selected
In this blog, we have discussed how to call Watson Tone Analyzer from a SQL statement. The scenario above can be easily modified to utilize the result from Watson inside DB2 for z/OS, like joining the result with a DB2 table, etc. This open the door for building a cognitive DB2 for z/OS application, getting the best from both sides (Watson and DB2 for z/OS).
In Part 1, we have discussed how DB2 for z/OS can act as a REST Service consumer to consume JSON output from a REST service provider. In this article, we will discuss how DB2 for z/OS consumes XML output from a service provider.
HTTPGETCLOB is a UDF that send a request to a specified URL through an HTTP GET request. It takes two parameters: URL and optional http header. Output is a CLOB (5M). There are other similar UDFs, like HTTPGETBLOB, etc. See Resources section for details.
The following example is sending a request to Yahoo to ask for weather forecast for a city called Fremont inside California (same example as in Part 1 ()
SELECT DB2XML.HTTPGETCLOB(
CAST ('*%20from%20weather.forecast%20where%20woeid%20in%20%28select%20woeid%20from%20geo.places%281%29%20where%20text%3D%22fremont%2C%20ca%22%29&format=xml&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys' AS VARCHAR(255)),
CAST(NULL AS CLOB(1K)))
The output is in XML format (truncated):
The following statement allow us to extract ‘/query/results/channel/item/yweather:condition' from the output above:
With TABLEA as (
CAST(NULL AS CLOB(1K))) as DATA
FROM SYSIBM.SYSDUMMY1)
SELECT XMLQUERY(
'declare namespace yweather="";
/query/results/channel/item/yweather:condition' PASSING XMLPARSE(TABLEA.DATA)
)
FROM TABLEA
<yweather:condition xmlns:
In Query 2,
Assuming we are only interested in the forecast ‘/query/results/channel/item/yweather:forecast (see purple arrow in the output above), we can use Query 3 below to iterate each ‘/query/results/channel/item/yweather:forecast’ and display it in relational format.
SELECT XT.* FROM
TABLEA, XMLTABLE(
/query/results/channel/item/yweather:forecast' PASSING XMLPARSE(TABLEA.DATA)
COLUMNS
date VARCHAR(11) PATH '@date',
high INT PATH '@high',
low INT PATH '@low',
text VARCHAR(20) PATH '@text') XT
Output:
DATE HIGH LOW TEXT
10 record(s) selected
In Query 3,
<yweather:forecast xmlns:
<yweather:forecast xmlns:
<yweather:forecast xmlns:
<yweather:forecast xmlns:
<yweather:forecast xmlns:
<yweather:forecast xmlns:
<yweather:forecast xmlns:
<yweather:forecast xmlns:
<yweather:forecast xmlns:
<yweather:forecast xmlns:
In Part 1, we have discussed how to make DB2 for z/OS as a REST service consumer using HTTPGETCLOB and JSON features inside DB2 for z/OS. In Part 2, we show how DB2 for z/OS consumes XML output from a service provider.
JSON (Java Object Notation) is one of the most commonly used output format from REST services. With JSON support in DB2 for z/OS, DB2 for z/OS can act as a REST Service consumer to consume JSON output. In the following sections in this article, I will describe how DB2 for z/OS can achieve this.
In Part 2, we will discuss how DB2 for z/OS consumes XML output from a service provider ().
The following example is sending a request to to ask for the country info for US.
CAST ('' ||
DB2XML.URLENCODE('en','') ||
'&country=' ||
DB2XML.URLENCODE('us','') ||
'&type=JSON' AS VARCHAR(255)),
The output is in JSON format (reformat for readability):
{ "status":
{ "message": "Please add a username to each call in order for geonames to be able to identify the calling application and count the credits usage.",
"value ":10
The following statement allow us to extract status.value from the output above:
with tablea as (
select JSON_VAL(SYSTOOLS.JSON2BSON(DATA), 'status.value', 'i')
from tablea
10
1 record(s) selected
We first use common table expression (CTE, or inline table) to create a “table” called tablea to store the result of HTTPGETCLOB() as DATA. Then, we pass DATA to SYSTOOLS.JSON2BSON() to convert text format of DATA to BSON(Binary format of JSON). BSON is the DB2 for z/OS internal storage format for JSON. This is required since JSON_VAL can only apply on BSON. JSON_VAL() is a built-in function that extract 'status.value' from DATA and convert the result into a SQL integer type.
The following query is sending a request to Yahoo to ask for weather forecast for a city called Fremont inside California.
CAST ('*%20from%20weather.forecast%20where%20woeid%20in%20%28select%20woeid%20from%20geo.places%281%29%20where%20text%3D%22fremont%2C%20ca%22%29&format=json&env=store%3A%2F%2Fdatatables.org%2Falltableswithkeys' AS VARCHAR(255)),
Output (reformat for readability):
"query": {
….
"results": {
"channel": {
…
"item": {
"title": "Conditions for Fremont, CA, US at 01:00 PM PDT",
….
"forecast": [{
"code": "28",
"date": "07 Oct 2016",
"day": "Fri",
"high": "86",
"low": "53",
"text": "Mostly Cloudy"
"code": "32",
"date": "08 Oct 2016",
"day": "Sat",
"high": "89",
"low": "56",
"text": "Sunny"
"code": "30",
"date": "09 Oct 2016",
"day": "Sun",
"high": "83",
"low": "55",
"text": "Partly Cloudy"
}, ….
],
…
}
}
Assuming we are only interested in 'query.results.channel.item.forecast' , which is a array structure. We can use Query 4 below to extract 'query.results.channel.item.forecast' and display it in relational format.
CAST(NULL AS CLOB(1K))) AS DATA
select JSON_VAL(SYSTOOLS.JSON2BSON(X.VALUE), 'date', 's:20') as date,
JSON_VAL(SYSTOOLS.JSON2BSON(X.VALUE), 'high', 'i') as temperature_high,
JSON_VAL(SYSTOOLS.JSON2BSON(X.VALUE), 'low', 'i') as temperature_low,
JSON_VAL(SYSTOOLS.JSON2BSON(X.VALUE), 'text', 's:20') as description
from tablea,
TABLE(SYSTOOLS.JSON_TABLE(SYSTOOLS.JSON2BSON(DATA), 'query.results.channel.item.forecast', 's:200')) X
Output will be nicely formatted in a relational format:
DATE TEMPERATURE_HIGH TEMPERATURE_LOW DESCRIPTION
In Query 4,
In this blog, we have discussed how to make DB2 for z/OS as a REST service consumer using HTTPGETCLOB and JSON features inside DB2 for z/OS. In Part 2, we will discuss how DB2 for z/OS consumes XML output from a service provider ().
This blog is the third one of a series of blogs in this topic.
In Part1, we discussed about scala.xml.XML () .
In Part 2, we discussed about com.databricks.spark.xml package with a single XML document. ()
In this article, we will discuss how to use databricks XML package on XML data stored in DB2 for z/OS. Doing so is not as easy as I thought initially, we are facing some challenges (as of time writing this article)
To resolves these challenges, I need to create a lot of “helper” functions. I am using the technique of Inferring the Schema using Reflection from.
Below is a summary of steps:
If you have not done so, please follow Part 1
It is highly recommended you read Part 2 to get some basic idea on databricks XML package.
Use –packages option to pull in databricks package
For Scala 2.10, I use the following command:
C:\Spark162\spark-1.6.2-bin-hadoop2.6\bin\spark-shell.cmd --packages com.databricks:spark-xml_2.10:0.3.3
scala> val customSchema =
StructType(Array(
StructField("@partNum",StringType,true),
StructField("productName",StringType,true),
StructField("quantity",LongType,true),
StructField("USPrice",DoubleType,true),
StructField("shipDate",StringType,true),
StructField("comment",StringType,true)
))
def writeNLoadSchema(data: String) = {
scala.tools.nsc.io.File("JaneTempFile").writeAll(data)
sqlContext.read.format("com.databricks.spark.xml").option("rowTag", "item").schema(customSchema).load("JaneTempFile")
scala>case class Item(partNum: String, productName: String, quantity: Long, USPrice: Double, shipDate : String, comment: String)
()
def createItemFromSeq(params: Seq[Any]) = {
Item.getClass.getMethods.find(x => x.getName == "apply" && x.isBridge).get.invoke(Item, params map (_.asInstanceOf[AnyRef]): _*).asInstanceOf[Item]
def createSingleLevelArray(A: Array[Array[org.apache.spark.sql.Row]]) : Array[org.apache.spark.sql.Row] = {
var count :Int = 0
for(x <- 0 until A.length) {
for(y <- 0 until A(x).length) {
count = count + 1
}
val resultA = new Array[org.apache.spark.sql.Row](count)
count = 0
resultA(count) = A(x)(y)
count = count + 1
}
return resultA
Scala> val xmlDF = sqlContext.load("jdbc", Map("url" -> "jdbc:db2://<hostname>:<port>/<dbname>:currentSchema=<schema>;user=<userid>;password=<password>;","driver" -> "com.ibm.db2.jcc.DB2Driver", "dbtable" -> "SYSADM.T1"))
Scala> var xmlColArray = (xmlDF.select(xmlDF("XMLCOL"))).map( _.getString( 0 ) ).collect().map(writeNLoadSchema(_).collect())
res5: Array[Array[org.apache.spark.sql.Row]] =
Array(Array([872-AA,Lawnmower,1,149.99,2013-11-20,null],
[945-ZG,Sapphire Bracelet,2,178.99,null,Not shipped]),
Array([900-AA,pen,1,5.0,2013-11-20,null],
[145-ZG,Johnson lotion,2,10.0,null,Not shipped],
[945-ZG,Sapphire Bracelet,3,178.99,null,Not shipped]))
Conceptually, xmlColArray is something like this:
<PO ..id=“123”>…
<PO ..id=“999”>…
Item(
partNum
productName
Quantity
USPrice
shipDate
comment)
Done in step 0c above
Scala> var itemsArray = (createSingleLevelArray(xmlColArray)).map(_.toSeq).map(createItemFromSeq(_))
itemsArray: Array[Item] =
Array(Item(872-AA,Lawnmower,1,149.99,2013-11-20,null),
Item(945-ZG,Sapphire Bracelet,2,178.99,null,Not shipped),
Item(900-AA,pen,1,5.0,2013-11-20,null),
Item(145-ZG,Johnson lotion,2,10.0,null,Not shipped),
Item(945-ZG,Sapphire Bracelet,3,178.99,null,Not shipped))
Conceptually, itemsArray is something like this:
Item(872-AA,Lawnmower,1,149.99,2013-11-20,null)
Scala> var itemsDF = sc.parallelize(itemsArray).toDF
Now, you can use DataFrame APIs, like
Scala> itemsDF.show()
+-------+-----------------+--------+-------+----------+-----------+
|partNum| productName|quantity|USPrice| shipDate| comment|
| 872-AA| Lawnmower| 1| 149.99|2013-11-20| null|
| 945-ZG|Sapphire Bracelet| 2| 178.99| null|Not shipped|
| 900-AA| pen| 1| 5.0|2013-11-20| null|
| 145-ZG| Johnson lotion| 2| 10.0| null|Not shipped|
| 945-ZG|Sapphire Bracelet| 3| 178.99| null|Not shipped|
To find all the productName and count
Scala> itemsDF.groupBy("productName").count.show
+-----------------+-----+
| productName|count|
| Johnson lotion| 1|
| pen| 1|
| Lawnmower| 1|
|Sapphire Bracelet| 2|
Scala> itemsDF.registerTempTable("itemstable")
To find average price of all items and order by productName:
Scala> val results =sqlContext.sql("SELECT productName, AVG(USPrice) as average_price FROM itemstable GROUP BY productName order by productName").show
+-----------------+-------------+
| productName|average_price|
| Johnson lotion| 10.0|
| Lawnmower| 149.99|
|Sapphire Bracelet| 178.99|
| pen| 5.0|
To find the best selling item in term of total price:
Scala> val results =sqlContext.sql("SELECT productName, SUM((USPrice * quantity)) as total_price FROM itemstable GROUP BY productName order by total_price desc").show
+-----------------+-----------+
| productName|total_price|
|Sapphire Bracelet| 894.95|
| Lawnmower| 149.99|
| Johnson lotion| 20.0|
| pen| 5.0|
If you are familiar to pureXML in DB2 for z/OS, you may know many of above queries can be rewritten using XQuery or XMLTABLE functions that you can execute directly inside DB2 for z/OS, without pulling data outside DB2. The XML data stored in DB2 for z/OS is a “parsed” format that optimized for fast retrieval. On top of that, XML indexes can be created to improve query performance.
To answer above question, I believe there is no “one size fit all”. Before making any decision, consider the following questions:
We have discussed how to use Spark, mainly scala.xml.XML and databricks XML package, to analyze the XML data stored in DB2 for z/OS. | https://www.ibm.com/developerworks/community/blogs/e429a8a2-b27f-48f3-aa73-ca13d5b69759?tags=db2z&lang=en | CC-MAIN-2019-26 | refinedweb | 7,172 | 51.44 |
Article: Adding Properties to Ruby Metaprogramatically
If you're coming over to Ruby from the Java world, and want a good primer on what metaprogramming is all about, then definitely read Adding Properties to Ruby Metaprogramatically today.
Good article, but many errors.
by
Jules Jacobs
define_method("#{sym}".to_sym) {
instance_variable_get("@#{sym.to_s}")
}
Why do you convert sym to a string and then back to a symbol? It's more common to use do...end for blocks where the open brace is not on the same line as the end brace.
define_method("#{sym}=".to_sym) {|value|
instance_variable_set("@#{sym.to_s}", value)
}
You don't need to convert the thing to a symbol. define_methods accepts strings too. You don't have to use sym.to_s either as it's already converted to a string by string interpolation. Same thing for do...end.
define_method(:direction=){|value|
instance_variable_set("@#{sym.to_s}", value)
fire_event_for(:direction)
}
Why do you have :direction= and :direction in there, but also #{sym.to_s}? This code will not work.
define_method("add_#{sym}_listener".to_sym){|x|
@listener[:sym] << x
}
to_sym is not necessary here. @listener[:sym] should be @listener[sym].
"The code for setting up the listener lists and the rest is left to the reader as exercise. (Stop moaning, it's just 3 lines of code)."
Could you give these 3 lines? I don't know how to do it (without cheating by putting multiple things on one line). The fire_event_for will be at least three lines of code. Setting up the listener hash table is also hard with this implementation. So again: please show the code :)
h = CruiseShip.new
h.add_direction_listener(Listener.new())
h.add_bar_listener lambda {|x| puts "Oy... someone changed the property to #{x}"}
h.hello = 10
Where do you define the class Listener? Where does add_bar_listener come from? Where does hello= come from? Why does the bar_listener get called if you call hello=(10)?
class Ship
extend Properties
end
Maybe it's good to explain that extend adds the methods to the Ship class object and not to the Ship instances? This is not the common way to use mixins in Ruby. Well maybe it's better to pretend that it's this simple.
property :speed {|v| v >= 0 && vn< 300 }
This code won't parse. You need parens here.
def property(x, &predicate)
define_method("#{sym}=".to_sym) {|arg|
if(!predicate.nil?)
if !predicate.call(arg)
return
end
end
instance_variable_set("@#{sym.to_s}", arg)
prop_holder = instance_variable_get("@#{sym.to_s}_property_holder")
prop_holder.fire_event(arg) if prop_holder
}
end
OK. to_sym not necessary. "!predicate.nil?" is the same as "predicate". Why do you use braces for the first if but not for the second? to_s is redundant (2x). Where do you set @#{sym}_property_holder? What is prop_holder? What is prop_holder.fire_event?
property :speed, in([0..300]
Missing close paren ;-). Why do you put the range in an array?
property :speed, in(0..300)
def in(x)
lambda{|value| x === value}
end
This will allow you to pass a regex:
property :email, in(/email regex/)
But the name "in" isn't very good now. That's not a problem because you cannot use "in" anyway because it's a reserved word.
I hope you fix the errors. This is a great article if you do.
Working on fixes and article will be updated.
by
Obie Fernandez
Re: Good article, but many errors.
by
Werner Schuster
I guess it serves me right for copy/pasting code between evolving source code and an evolving article text - nothing good can come from that.
The more stupid errors will be fixed right away;
Let me address your questions:
- extending a Module
If I _include_ a Module, the methods will be added as instance methods, but to have
something like this
class Foo
property :xyz
end
they need to be available as class methods. With include, you'd call them as instance
methods so... I guess you'd have to setup the properties in the constructor or somewhere else. If I'm missing a better way to do this, I'd be interested to hear;
- the do/end vs braces thing...
well, I don't know, I like the braces; there's a precedence difference between the two, but otherwise it seems to be a matter of taste... also: the word "do" feels like clutter, and I wanted to make the solution seem as clean as possible; There's no real reason why there's a difference for delimiting blocks - Smalltalk uses brackets for _all_ blocks;
- thanks for the === tip;
- good catch on the "in" keyword... I updated the article to mention this; however, the ideas in this section were thought of as possible notations, that the user could play with (as always with internal DSLs, it's good to come up with the look, then chip away at it and prop some parts up to make it Ruby code);.
Again... thanks for keeping me honest, Jules!
Extending Modules
by
Werner Schuster
Re: Extending Modules
by
Jules Jacobs
module Example
def instance_method
# this method will be added to the class as an instance method
end
module ClassMethods
def class_method
# this method will be added to the class as a class method
end
end
def self.included(klass)
klass.extend(ClassMethods)
end
end
class Test
include Example # this will call the Example.included callback
end
If you need only class methods just using extend in the class that needs the Properties seems cleaner.
The article has been re-published with corrections.
by
Obie Fernandez
Listeners and predicate
by
Victor Cosby
module Properties
def self.extended(base)
base.class_eval %q{def fire_event_for(sym, *arg) @listener[sym].each {|l| l.call(arg) } end }
end
def property(sym, &predicate)
...
define_method("add_#{sym}_listener") do |x|
@listener ||= {}
@listener[sym] ||= []
@listener[sym] << x
end
end
but I'd love to know how you've gotten the predicate business to work.
property :speed {|v| v >= 0 && vn< 300 }won't even parse.
Re: Listeners and predicate
by
Victor Cosby
module Properties
def self.extended(base)
base.class_eval %q{def fire_event_for(sym, arg) @listener[sym].each {|l| l.call(arg) } end }
end
# def property(sym, &predicate)
def property(sym, predicate=nil)
define_method(sym) do
instance_variable_get("@#{sym}")
end
define_method("#{sym}=") do |arg|
return if !predicate.call(arg) if predicate
instance_variable_set("@#{sym}", arg)
fire_event_for(sym, arg)
end
define_method("add_#{sym}_listener") do |x|
@listener ||= {}
@listener[sym] ||= []
@listener[sym] << x
end
define_method("remove_#{sym}_listener") do |x|
@listener[sym].delete_at(x)
end
end
def is(test)
lambda {|val| test === val }
end
end
class CruiseShip
extend Properties
property :direction
# property(:speed) {|v| v >= 0 && v < 300 }
property :speed, is(0..300)
end
h = CruiseShip.new
h.add_direction_listener(lambda {|x| puts "Oy... someone changed the direction to #{x}"})
h.direction = "north"
h.add_speed_listener(lambda {|x| puts "Oy... someone changed the speed to #{x}"})
h.add_speed_listener(lambda {|x| puts "Yo, dude... someone changed the speed to #{x}"})
h.speed = 200
h.speed = 300
h.speed = 301
h.speed = -1
h.speed = 2000
puts h.direction
puts h.speed
h.remove_speed_listener(1)
h.speed = 200
h.speed = 350
puts h.direction
puts h | http://www.infoq.com/news/2007/04/article-adding-ruby-properties | CC-MAIN-2015-14 | refinedweb | 1,174 | 69.38 |
To facilitate the development of robust, error-free code, Apex Code requires the creation and execution of unit tests. Unit tests are comprised of test methods and classes that verify whether a particular piece of code is working properly.
This article introduces test methods. It details why test methods are a critical part of Force.com application development, test method syntax, best practices, and advanced topics such as test methods for Visualforce controllers and Apex web service callouts.
To facilitate and promote the development of robust, error-free code, Apex Code requires the creation and execution of unit tests. Unit tests are class methods that verify whether a particular piece of code is working properly. Unit tests are written in Apex Code and annotated with the
testMethod keyword (we will go into formal syntax in the next section).
It is important to understand that test methods are required to deploy Apex to a production environment. They are also required if your code is going to be packaged and placed on Force.com AppExchange. The test methods must provide at least 75% code coverage. Think of a test method as 'Apex code that tests other Apex code.' Code coverage is calculated by dividing the number of unique Apex code lines executed during your test method execution by the total number of Apex code lines in all of your trigger and classes. (Note: these numbers do not include lines of code within your testMethods)
It is also important to not think of test methods as simply a requirement by the Force.com platform. It should not be an afterthought. Writing test methods should be a critical part of Force.com development and they are required to ensure your success. Test methods provide test automation which can enable greater QA efficiency. It also provides an automated regression testing framework to validate bug fixes or future development enhancements.
The following sections of this article will help articulate test method syntax, illustrate how to execute test methods, and elaborate on the key best practices.
As discussed earlier, test methods are written in Apex Code. If you are unfamiliar with Apex, check out the article An Introduction to Apex Code.
testMethodkeyword
To define an Apex method as a 'test method', simply define the method as
static and add the keyword
testMethod. A test method can be defined in any Apex class. A test method can not be defined in an Apex trigger. (Note: Testmethods cannot be called outside of a test context.) Here's a simple example:
public class myClass { static testMethod void myTest() { // Add test method logic using System.assert(), System.assertEquals() // and System.assertNotEquals() here. } }
isTestannotation
Use the
isTest class annotation to define classes that only contain code used for testing your application. If your test methods are contained within their own classes and the Apex class only contains test methods, it is ideal to use the
isTest annotation.
Classes defined with the
isTest annotation do not count against your organization limit of 2 MB for all Apex code. Classes annotated with
isTest can be declared as private or public. They cannot be interfaces or enums either.
Here is an example of the syntax:
@isTest private class MyTest { // Methods for testing }
There are two additional system static methods provided by Apex. These methods,
Test.startTest and
Test.stopTest, are used when testing governor limits. Or in other words, executing test scenarios with a larger data set.
The
Test.startTest method marks the point in your test code when your test actually begins. Each test method is allowed to call this method only once. All of the code before this method should be used to initialize variables, populate data structures, and so on, allowing you to set up everything you need in order to run your test. After you call this method, you get a fresh set of governor limits for the remainder of the test until you call
Test.stopTest.
The
Test.stopTest method marks the point in your test code when your test ends. Use this method in conjunction with the
startTest method. Each test method is allowed to call this method only once. After calling this method, any post assertions are done in the original context.
These static methods allow a test method to separate the Apex resources and governor limits being used to prepare and initialize the dataset from the resources and limits used during the actual test execution.
Here is a sample test method function that uses these methods:
static testMethod void verifyAccountDescriptionsWhereOverwritten(){ // Perform our data preparation. List<Account> accounts = new List<Account>{}; for(Integer i = 0; i < 200; i++){ Account a = new Account(Name = 'Test Account ' + i); accounts.add(a); } // Start the test, this changes governor limit context to // that of trigger rather than test. test.startTest(); // Insert the Account records that cause the trigger to execute. insert accounts; // Stop the test, this changes limit context back to test from trigger. test.stopTest(); // Query the database for the newly inserted records. List<Account> insertedAccounts = [SELECT Name, Description FROM Account WHERE Id IN :accounts]; // Assert that the Description fields contains the proper value now. for(Account a : insertedAccounts){ System.assertEquals( 'This Account is probably left over from testing. It should probably be deleted.', a.Description); } }
trigger OverwriteTestAccountDescriptions on Account (before insert) { for(Account a: Trigger.new){ if (a.Name.toLowerCase().contains('test')){ a.Description = 'This Account is probably left over from testing. It should probably be deleted.'; } } }
The example above helps illustrate how to separate the test data preparation from the actual test scenario. The first step of the example creates 200 Accounts that are required for the test scenario-and inserting these 200 Account records will have them applied to the governor limits. So in order to separate the Apex resources and governor limits used during test data preparation from the actual test scenario, the example uses the
Test.startTest() and
Test.stopTest() methods. Therefore, the Apex code executing within the startTest and stopTest methods will obtain their own Apex governor limits and resources. If the test method did not use
startTest() and
stopTest(), the test scenario might have hit a governor limit since some of the available Apex resources (such as total number of records processed by a DML statement) were used up by data preparation steps..
Please note that the runAs() functionality will test and verify proper data sharing and data access. But
runAs() does not validate CRUD or Field Level Security permissions.
public class TestRunAs { public static testMethod void testRunAs() { // Setup test data // This code runs as the system user Profile p = [select id from profile where name='Standard User']; User u = new User(alias = 'standt', email='[email protected]', emailencodingkey='UTF-8', lastname='Testing', languagelocalekey='en_US', localesidkey='en_US', profileid = p.Id, timezonesidkey='America/Los_Angeles', username='[email protected]'); System.runAs(u) { // The following code runs as user 'u' System.debug('Current User: ' + UserInfo.getUserName()); System.debug('Current Profile: ' + UserInfo.getProfileId()); } // Run some code that checks record sharing } }
The above test method creates a new user (with a profile of a standard user), and executes a block of code in the context of this new user.
There are 2 primary ways to execute test methods:
The following section shows how to execute test methods in each of these environments.
You can run unit tests for a specific class or you can run all the unit tests in your organization using the Salesforce User Interface.
To run the unit tests for a specific class, click Setup | Develop | Apex Classes, click the name of the class, then click Run Test. If your class calls another class or causes a trigger to execute, those Apex code lines are included in the total amount used for calculating the percentage of code covered.
To run all the unit tests in your organization, click Setup | Develop | Apex Classes, then click Run All Tests.
The result page for running unit tests contains the following:
Here's a screenshot showing these data for a test run:
In addition to executing test methods through the Salesforce user interface, test methods can be executed from within the Force.com IDE. If you aren't familiar with the Force.com IDE, please visit Force.com IDE for installation and documentation.
Using the IDE, you can run all the test methods for the organization or you can run just the test methods for a particular Apex class.
To run all test methods in a given organization, go to the Force.com Ide, select the project, expand the project until you see the Classes folder, and right click. Next, open up the Force.com properties and select 'Run All Tests':
The output or results will be displayed in the Apex Test Runner view. You must be in the Force.com perspective within Eclipse to see the Apex Test Runner view. This is where you will see the results for number of tests run, number of failures, code coverage percentage, debug log, and so on:
This section contains a bulleted list of several key tips and best practices. For additional information, see the article How to Write Good Unit Tests which explores the proper structure of unit tests, the code scenarios that unit tests should cover, and the properties of well-written unit tests in additional depth.
For example, here is a poorly written test method that hardcodes the expected test data:); // INCORRECT - By hardcoding this Product Name in the test method, the test method // will fail in every other org where this code is deployed becuase the hardcoded // Product Id won't exist there. Product2 prod = [select id, name from Product2 where Name='Router']; prod.productcode='RTR2000'; update prod; // Verify that the productcode field was updated in the database. Product2 updatedProduct = [SELECT productcode FROM Product2 WHERE Id = :prod.Id]; System.assertEquals('RTR2000', updatedProduct.productcode); }
Now here is the properly written, portable test method.
static testMethod void myTestDynamicIds(){ // CORRECT - Create the required test data needed for the test scenario. // In this case, I need to update an Account to have a BillingState='CA' // So I create that Account in my test method itself. Account testAccount = new Account(name='Test Company Name'); insert testAccount; testAccount.billingState='CA'; update testAccount; // Verify that the billingState field was updated in the database. Account updatedAccount = [SELECT billingState FROM Account WHERE Id = :testAccount.Id]; System.assertEquals('CA', updatedAccount.billingState); // CORRECT - In this case, I need to update a Product to have a productcode ='RTR2000' // So I create that Product2 record in my test method itself. Product2 prod = new Product2(name='Router'); insert prod; prod.productcode='RTR2000'; update prod; // Verify that the productcode field was updated in the database. Product2 updatedProduct = [SELECT productcode FROM Product2 WHERE Id = :prod.Id]; System.assertEquals('RTR2000', updatedProduct.productcode); }
System.assertmethods to prove that code behaves properly.
runAsmethod to test your application in different user contexts.
The following sections provides some additional advice on these and other best practices.
Since Apex code executes in bulk, it is essential to have test scenarios to verify that the Apex being tested is designed to handle large datasets and not just single records To elaborate, an Apex trigger can be invoked either by a data operation from the user interface or by a data operation from the Force.com SOAP API. And the API should send multiple records per batch, leading to the trigger being invoked with several records. Therefore, it is key to have test methods that verify that all Apex code is properly designed to handle larger datasets and that it does not exceed governor limits.
The example below shows you a poorly written trigger that does not handle bulk properly and therefore hits a governor limit. Later, the trigger is revised to properly handle bulk datasets.
First,, billingState='testing',firstname='apex');.LimitException will be thrown when it hits a governor limit. Since the trigger shown above executes a SOQL query for each Contact in the batch, this test method throws the exception 'Too many SOQL queries: 101'. A trigger can only execute at most 100 queries.
Now let's correct the trigger to properly handle bulk operations. The key to fixing this trigger is to get the SOQL query outside the
for loop and only do 1.
Custom controllers and controller extensions, like all Apex code, require test methods. So don't forget to develop the proper test methods when developing Visualforce controllers. Test methods that cover controllers can automate the user interaction by setting query parameters, or navigating to different pages. There are some additional Apex classes that assist in writing test methods for Visualforce controllers.
Here is an example provided in the Visualforce Reference Guide with additional comments to highlight some of the key features and functions:
public static testMethod void testMyController() { //Use the PageReference Apex class to instantiate a page PageReference pageRef = Page.success; //In this case, the Visualforce page named 'success' is the starting point of this test method. Test.setCurrentPage(pageRef); //Instantiate and construct the controller class. thecontroller controller = new thecontroller(); //Example of calling an Action method. Same as calling any other Apex method. //Normally this is executed by a user clicking a button or a link from the Visualforce //page, but in the test method, just test the action method the same as any //other method by calling it directly. //The .getURL will return the page url the Save() method returns. String nextPage = controller.save().getUrl(); //Check that the save() method returns the proper URL. System.assertEquals('/apex/failure?error=noParam', nextPage); //Add parameters to page URL ApexPages.currentPage().getParameters().put('qp', 'yyyy'); //Instantiate a new controller with all parameters in the page controller = new thecontroller(); //Example of calling the 'setter' method for several properties. //Normally these setter methods are initiated by a user interacting with the Visualforce page, //but in a test method, just call the setter method directly. controller.setLastName('lastname'); controller.setFirstName('firstname'); controller.setCompany('acme'); controller.setEmail('[email protected]'); nextPage = controller.save().getUrl(); //Verify that the success page displays System.assertEquals('/apex/success', nextPage); }
Note how you can reference pages, instantiate controllers, add parameters and invoke actions methods.
Apex Code has built in functionality to call external Web services, such as Amazon Web Services, Facebook, Google, or any publicly available web service. As a result, you will need to have the proper test method code coverage for the related Apex code that makes these callouts. But since the Force.com platform has no control over the external Web service and the impact of making the web service call, test methods can not invoke a 3rd party web service. This section provides a viable workaround to ensure proper code coverage.
The main part of this solution is not in the test method itself, but in the primary Apex Code that executes the web service call. It is recommended to refactor the Apex code into the following methods:
public HttpRequest buildWebServiceRequest(){ //Build HTTP Request object HttpRequest req = new HttpRequest(); req.setEndpoint(<insert endpoint url here>); req.setMethod('GET'); }
public HttpResponse invokeWebService(Http h, HttpRequest req){ //Invoke Web Service HttpResponse res = h.send(req); return res; }
public void handleWebServiceResponse(HttpResponse res){ //Parse and apply logic to the res message }
Now that the web service execution is broken up into these subsections with each handling a subset of the request-response, the 3 Apex methods can be invoked in order from the main Apex code script. For example:
public void main(){ //apply business logic //now need to make web service callout //First, build the http request Http h = new Http(); HttpRequest req = buildWebServiceRequest(); //Second, invoke web service call HttpResponse res = invokeWebService(h, req); //Last, handling the response handleWebServiceResponse(res); //continue with the apex script logic }
With this refactored web service code in place, we are ready to write the test method to obtain proper code coverage. With the web service processing broken up into 3 methods, we can test all of the Apex methods except for the small method that performs the web service call. For example:
static testMethod void testWebService(){ //First, build the http request HttpRequest req = buildWebServiceRequest(); //NOTE - WE DO NOT EXECUTE THE METHOD, invokeWebService. //Now, since we can't execute the actual web service, //write apex code to build a sample HttpResponse object HttpResponse res = new HttpResponse(); //Apply test data and attributes to the HttpResponse object as needed handleWebServiceResponse(res); }
The key to this solution is to refactor the Apex logic to break out (a) building the web service request (b) the actual web service invocation and (c) the handling of the web service response. This allows the test methods to validate (a) building the web service request and (b) handling of the web service response without truly invoking the web service.
This article provides an introduction to starting your test method development. It explores the syntax for creating test methods, shows how to execute these tests, and provide best practice advice. Test methods are not intended to be roadblocks to your development. Rather, they ensure your success. Do not approach testing and developing your test methods as an afterthought. Test methods should be written during the development effort. Valid test methods will provide you with an automated test suite to ensure quality and execute regression testing.
Andrew Albert is a Technical Evangelist at salesforce.com, focusing on the Force.com Platform. | https://developer.salesforce.com/page/An_Introduction_to_Apex_Code_Test_Methods | CC-MAIN-2018-34 | refinedweb | 2,880 | 54.63 |
Hi
What is the best way to get to Dendera Temple from Luxor and does anyone know the cost of this please?
The last time I looked, you can hire a cab for about LE 300–350 (there and back) for the car, not per person. Depending upon what is happening at the time, however, the authorities may require you travel in a convoy or less likely not go at all. The large holiday companies will have organised tours which will be more expensive.
You can also take a day’s sail on the “Lotus Boat” , a smallish Nile cruise ship which travels between Luxor and Dendera once or twice a week. The cost is roughly LE 400 per person. These sailings, however, are subject to cancelation or rescheduling if not enough tickets have been sold.Edited: 11:59 pm, January 31, 2013
I traveled by mini bus ...I think the boat would be a better option though
We went by taxi last month. There were no convoys or restrictions in place. We agreed 180LE return (for the taxi, not per person) from Luxor with 2 hours' waiting time at the temple. We virtually had the place to ourselves. Don't miss the crypt - truly impressive.
We like the cruise it a good day out cost us 35 English.
We like the cruise it a good day out cost us 35 English.
We like the cruise it a good day out cost us 35 English.
Sorry about the multiple posts peeps.
We did the cruise & thought it was far too long. left the hotel at 6.30am & didn't get back until 7.30pm. It was very cold with the breeze on the river even though the temp in Luxor was around 25c when we were there in December. Food was 'adequate' & there was nothing of any real interest to see on the journey.
However Dendara is a must. If we went back would definitely go by taxi & stop off for a nice lunch somewhere.
I went to Dendera 18 moths ago by taxi, I was charged 150le (there and back), great temple.
Been lots of times on the Lotos boat to Dendra 35 pound english lots to see on the way country side and egyption people going about there daily life on the banks its very nice and relaxing. | http://www.tripadvisor.com/ShowTopic-g294205-i9426-k6100245-Dendera_Temple-Luxor_Nile_River_Valley.html | CC-MAIN-2013-20 | refinedweb | 390 | 81.93 |
Comment on Tutorial - A sample that shows Java Beans, Servlets and JSP working together By Ivan Lim
Comment Added by : Vitalis
Comment Added at : 2014-04-29 17:47:16
Comment on Tutorial : A sample that shows Java Beans, Servlets and JSP working together By Ivan Lim
In the absence of frameworks, this is the best example of retrieving composite attributes from a bean, I have come across. Thanks for. Simpler example:
import java.io.*;
View Tutorial By: Joseph Harner at 2011-12-04 23:20:48
2. The code is really helpfull...
reading or w
View Tutorial By: sharda at 2010-03-11 03:28:02
3. the code works fine,i also tried the write code.th
View Tutorial By: Joy at 2013-11-25 05:24:23
4. Great!
Thnks for your help..
View Tutorial By: ramu at 2011-06-18 07:56:56
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View Tutorial By: Arif at 2008-10-09 11:29:14
7. What's with the \ " ?
Your code doesn
View Tutorial By: Dan at 2011-12-29 10:20:08
8. Hi sir !
I have two Crystal Report
View Tutorial By: Anderson Abad at 2011-07-20 03:34:51
9. good job.. i understand it clearly..
its in
View Tutorial By: xmplexd at 2010-08-04 02:12:30
10. Thanks.It helps a lot to me.
View Tutorial By: Sachin at 2013-05-24 19:36:36 | https://java-samples.com/showcomment.php?commentid=39520 | CC-MAIN-2019-43 | refinedweb | 271 | 76.62 |
Creating a .NET DLL that can be accessed through COM is a three step process1. Create the DLL in .NET2. Register the types in .NET DLL and make then avaliable to COM3. Call the DLL through COM in VBA
1. Create the DLL in .NETIn order to make a DLL that can be callable through COM there are a number of rules that need to be followed these are summarised below, for more information search for 'Qualifying.NET Types for Interoperation' in Visual Studio's help files.
Rules:Classes should implement interfaces explicitly.Although COM interop provides a mechanism to automatically generate an interface containing all members of the class and the members of its base class, it is far better to provide explicit interfaces. The automatically generated interface is called the class interface. Managed types must be public.Only public types in an assembly are registered and exported to the type library. As a result, only public types are visible to COM.. The following rule also applies although not covered in the above:
The DLL assembly must be strongly named and installed to the GAC.COM can only access managed assemblies if they are stored in the GAC. The DLL that must be accessed through COM should be given a strong name and a version number. Here is a very simple example of a .NET class that will be made available to COM. It is written in C# however it is easy enough to translate to VB.NET
namespace HelloWorldDLL
{
[ClassInterface(ClassInterfaceType.AutoDual)]
public class HelloWorld
public HelloWorld()
{}
[ComVisible (true)]
public void DisplayHelloWorld()
{ MessageBox.Show(@"Hello World!"); }
}
The important point of the code above is the use of ClassInterface and ComVisible attributes. ClassInterface is used to generate a type library interface that you use through COM, this will create intellisense support in VBA for the types available in the DLL. Once this class is compiled into a strongly named DLL your ready for step 2
2. Register the types in .NET DLL and make then avaliable to COMTo register the .NET DLL for access to COM you use the RegAsm.exe command prompt tool. Start the Visual Studio command prompt and navigate to the directory that contains the DLL. When you register the DLL you need to also create a type library, this tells COM what types are available in the DLL.To register and create the type library use the following commandRegAsm myDLL.dll /tlb:"C:\myPath\myTlb.tlb"To unregister useRegAsm myDLL.dll /unregisterOnce you've done that install the DLL into the GAC, this is an important step as without it COM will not be able to find the assembly and the process fails. Most articles online don't explicitly state this. **NOTE: it seems this may only be an important step for making managed code available to COM+. The type library generated seems to refer to the private assembly first and if not found then the GAC**During development your repeat this step many times. As you recompile your assembly you need to ensure the GAC contains the most recent version. I generally unregister the assembly then update it and then re-register it, whether this is overkill I'm not sure.Now your ready to use the DLL.
3. Call the DLL through COM in VBA To call the DLL through COM you need to add a reference to the type library that was generated in step 2. In the macro editor select Tools->References and in the dialog that appears select Browse. Find and select the *.tlb file, the root namespace of the managed DLL is now available in the list to select. Tick it and ok the dialog.Now you can create an instance of the managed class and call it's methods as you would any other VBA object. Dim objManaged As New HelloWorldDLL.HelloWorldobjManaged.DisplayHelloWorld
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Since I began learning Python, I've been amazed by how much you can do with it, and how easy it actually is once you get comfortable with it. I've always loved working on the terminal, so to make my learning a bit fun, I learned how to make cli apps with Click and made a Chuck Norris jokes app late last year:
I posted the app on PyPi and as a Python beginner, you can just imagine my joy on seeing something I did up on PyPi. PyPi! 😄 Awesome feeling.
Then yesterday, I had to take a break from work and decided to open Dev.to. I like to have my browser closed if I don't require it for whatever I'm doing to avoid distractions. So I switched workspaces, opened up my browser, clicked on the Dev.to bookmark and there I was. The idea just popped into my head: I could bypass all this if I had one command to open dev.to from the terminal. I was already on my terminal before anyway so this seemed like a good idea 😄. Of course, this could be done for any website - I just thought of Dev.to because that's what made me go through the process in the first place.
As usual, the community was very supportive!
I'll do that on the next post. Thanks! 😊
So here's how I did it.
In case you want to follow along, now's the time to create a new directory,
cd into it, and create your virtual environment.
$ mkdir open-dev.to $ cd open-dev.to $ virtualenv venv # pip install virtualenv if you don't have it $ source venv/bin/activate (venv) $ mkdir app (venv) $ touch app/__init__.py # this is where we'll write our code (venv) $ touch requirements.txt # this will hold the project's requirements
click & the
webbrowser module
At the heart of this whole thing is these two lines of code:
import click import webbrowser
webbrowser provides the powers to open the browser, and
click makes it a cli app.
webbrowser comes with python so all we need to install is
click.
(venv) $ pip install click (venv) $ pip freeze > requirements.txt # add the installed module to our requirements file
Now that we have what we need, we can go ahead to write the code. Add the following code to
app/__init__.py. I'll explain what each line does.
import click import webbrowser @click.command() @click.option('--tag', '-t', help='add a tag') def main(tag): """ Open a new dev.to browser tab on the browser """ if tag: url = '{}'.format(tag) else: url = '' webbrowser.open(url, new=2) if __name__ == "__main__": main()
It's really that simple! Even a beginner would be able to make sense of what this code does.
@click.command()
This click decorator converts the
main() function into a cli command. Without it, it would just be a normal python function. But with it, it becomes command that can be invoked as a command line utility.
@click.option('--tag', '-t', help='add a tag')
@click.option() extends the command to be able to accept extra arguments. In this case,
--tag or its shorthand version
-t is allowed. The
help text explains what the argument does.
def main(tag):
This is our app's entrypoint, where all the magic happens. The function (now a command) takes an optional
tag argument, which determines the url to be opened as seen in the
if else a few lines below it.
"""Open a new dev.to browser tab on the browser"""
webbrowser.open(url, new=2)
Opens the requested url.
new=2 makes sure this is done in a new tab.
And finally, the
if __name__ block runs the
main() function when the script runs.
Having the code above, just run the
__init__.py to see it work.
$ python app/__init__.py
A new Dev.to tab should automatically open on your browser.
$ python app/__init__.py --help Usage: __init__.py [OPTIONS] Open a new dev.to browser tab on the browser Options: -t, --tag TEXT add a tag --help Show this message and exit.
Let's try out passing in a tag.
$ python app/__init__.py --tag react should be opened 😀.
We don't want to keep running
python app/__init__.py everytime though. In the next post, I'll show how to use
setuptools to bundle the script so we can install it locally and use the simple
dev.to command to run the script instead of the long
python app/__init__.py. I'll also show how to publish a package on PyPi.
This was fun =) You should add a bit about the process, what you needed to make this happen and how to make a package to share. | https://dev.to/wangonya/how-i-made-the-open-dev-to-cli-app-with-python-54p0 | CC-MAIN-2020-50 | refinedweb | 799 | 84.27 |
> october 2004
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1
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Hashtable in Actionscript?
Posted by rafism at 10/27/2004 6:32:10 PM
Hi All, I am using Flash Remoting with Java, with my application server running on Tomcat. My Java application returns a Hashtable for a certain method, which internally is a Hashtable of Hashtables (containing many key-value pairs of values). I need to acess this from Actionscript in Flas...
more >>
dateFormat
Posted by justin.culp at 10/27/2004 3:55:09 PM
Does anyone know how to format a date from a SQL query? I have a webservice that simply gets the results of a query in a CFC throws it in a dataSet and then my dataGrid displays the data. One of the fields that is returned is a date field. In the SQL table the date reads 10/15/2004 but when...
more >>
Custom Object remoting
Posted by joe rage at 10/26/2004 6:00:06 PM
I am trying to pass custom object between Flash and my java application server using Flash Remoting. I was not able to make it work. I was wondering if someone had successfully done that and if so could provide how to do it. Thanks a lot, Joe ...
more >>
Remoting to run on Macintosh.
Posted by rafism at 10/26/2004 4:11:46 PM
Hi All, I am relatively new to Flash Remoting. I went through the concepts and found it to be very attractive. However, I want the Flash Remoting to be run on Macintosh (My Java App-server, the Tomcat server will be running on Macinstosh). I checked the Flash Remoting for J2EE, and fo...
more >>
Displaying images from database
Posted by lilla_m at 10/26/2004 1:09:06 PM
Does Flash Remoting have functions for displaying images (.gif, .jpg) saved as binary/blobs in a database, for example MSSQL 7? And if so, where can I get more information about it? (I don't have Flash MX 2004 installed at the moment, I'm just doing some research for an upcoming project). ...
more >>
Remoting webservices not working
Posted by nmg196 at 10/25/2004 4:58:21 PM
Hi, I'm trying to test my installation of the Flash Remoting server components by using the installed example at: But when I click the "Verify Credit Card" button, I get the following error message: "File or assembly name ExampleWeb...
more >>
SEND AND RETURN ARRAY TO CF FROM FLASH
Posted by neg at 10/24/2004 3:24:32 PM
Hello, Can anyone tell me how I can send two arrays from FLASH to CFMX, assign values to them using CFMX (values from a query) and return them back to FLASH. In other words, if I specify: <cfparam name="FLASH.flash01_Array" type="array"> <cfparam name="FLASH.flash02_Array" type="array...
more >>
When is component fully loaded?
Posted by Keith Dodd at 10/21/2004 9:41:14 PM
Have remoting working fine; but, where I have a Grid component on another frame in the timeline, I can't get the data to load--looks as if the component isn't actually loaded before I'm sending the data. The Grid along with a non-component text box is in a clip that has the linkage set to expo...
more >>
Don't see what you're looking for? Search DevelopmentNow.com.
Does anyboy Know where i could find...
Posted by _venger at 10/21/2004 6:51:05 PM
I want to get started in flash remoting applications using J2EE . Someone can tell me where i could find some examples to begin mey training?...
more >>
Text Area Component
Posted by bluestix at 10/21/2004 5:46:25 PM
I am using 3 text field components and a combobox in a form. The information changes in them based on the selected index of a datagrid. This works fine until I set the values of the text areas equal to a variable and pass them to a remoting call. After I do that the text in the fields won...
more >>
Sessions and Authentication in .NET
Posted by nmg196 at 10/21/2004 1:45:55 PM
Hi, If I have a flash remoting application, which accesses .NET web services, how do you control authentication? Do I have to write my own authentication back end, or is there some way to tie it in with .NET Forms Authentication? Also, is there any way to let the Flash app 'see' the sess...
more >>
datagrid pausing until rollover
Posted by jacobaa at 10/20/2004 2:09:52 PM
Using remoting to access my data, I am populating the datagrid with values. In one column of the datagrid I have a comboBox in each row that when changed will change the values in the rest of that row in the datagrid. The values are changing and accesssing the correct information - however - t...
more >>
My AMFPHP Flash app wont work
Posted by JoeBazz at 10/20/2004 1:33:36 AM
Well, I recently started developing a Flash front-end for my php system with the help of AMFPHP ... everything was fine until I decided to upload the files to the server ,to see if they?d work correctly there too...I then changed the setting in the gateway.php and the flash?s as code to match ...
more >>
Image from a database
Posted by JoeBazz at 10/19/2004 8:33:55 PM
Hello Friends, I wonder if its possible to load a blob data from a mysql table and load the content in a loader component, well actually I loaded the blob content into a array in flash but just don?t know a way to get the loader to load the content... maybe the nature of the same doesn?t ...
more >>
IP address of client
Posted by mbulat at 10/18/2004 9:31:05 PM
Does anyone know if it's possible to get the users remote ip address via flash remoting. I came across an example of this using the AMFPHP project () but can't find anything about doing this with flashremoting for .net. ...
more >>
Multiple Requests using Flash Remoting
Posted by seedolla at 10/18/2004 9:57:29 AM
Hi I am having a problem calling mutiple requests with Flash Remoting. I have flash file that calls remote methods on a statful java object on the server side that communicates with a servlet on the server-side. I can't seem to get multiple requests working on that servlet through the obje...
more >>
NetServices.as: File not found.
Posted by vegas NO[at]SPAM pagetraderinc.com at 10/16/2004 4:04:55 PM
NetServices.as: File not found. is missing. I have installed and re-installed the source code and the installer pack for actioscript 2.0. When I copy all the as files from First Run into the Flash directory I get a different error. Where is the connection found that translates to Flash MX whe...
more >>
Multiple service calls not working
Posted by bluestix at 10/15/2004 3:44:14 PM
I can make calls from Flash to ColdFusion on my server but in the file I am working on I can only get one call to return information. If I make any additional calls to the same service or define a new service and make calls to that they dont work. They dont return a result or a fault. Noth...
more >>
Updating Record Count in Datagrid during Download
Posted by mshe at 10/15/2004 2:51:44 PM
Hi all, Does anyone have an example to show me how to update the number of records in a datagrid while I am downloading data? For example if I have 200 records, I wish to show a realtime update of how many records have been downloaded to the client machine. Thanks. ...
more >>
enable flashgateway after running the updater?
Posted by WorkRequest at 10/13/2004 8:19:26 PM
After I run the CF MX Updater, my Flash appplication is stopped working. Then I found this instruction(below) from the website to enable it. Access from Macromedia Flash to web services using the Flash Gateway is disabled by default in Updater 3. To enable access from Macromedia Flash to we...
more >>
Update String won't Work
Posted by Silvertype at 10/13/2004 4:36:55 PM
Hi guys, I have a problem with updating my database in flash remoting mx. Whenever i try to update the table using a new value, the error below is thrown: Operation must use an updateable query Below's my code for updating the table called "poll.mdb". It is written in asp.net with VB.N...
more >>
Connecting with . net assemlies..
Posted by hotketu at 10/13/2004 12:39:23 PM
Hi i want to connect flash with .net assembly (.as) file and i want to use methods of that file. i am trying to connect using Flash remoting component 2004 but i am failed to get the output. can any one give me an idea about how to connect with .net assembly using Flash remoting comp...
more >>
Passing Arrays from Flash to CF ???!
Posted by phil ashby at 10/13/2004 9:14:57 AM
Hi all, wonder if you can help - I can't seem to get my head around arrays in CF. I'm passing an array from Flash...netdebug output below, but I can't work out how to access the different elements (data, label) within the array once in my CF function? The MM "help" doesn't, as usual... ...
more >>
RDBMSResolver does not process results_packet XML
Posted by madeiras at 10/11/2004 4:17:17 PM
Has it been fixed. REFERENCE: Topic Title: RDBMSResolver does not process results_packet XML Created On: 03/16/2004 02:42:43 PM Thanks...
more >>
Using Remoting AS2.0 with V2 UI Components
Posted by CFFLDave at 10/11/2004 3:53:01 PM
No offense, but is using V2 Remoting AS2.0 with V2 UI components, a covert military operation? I can find no articles with examples. I need to learn how to query, databind, and subsequently update a database. This should not be rocket science. Microsoft support (believe me I do not...
more >>
Is Flash Remoting Included With CFMX?
Posted by happy_christy at 10/8/2004 6:56:00 PM
I'm a little confused. Is Flash Remoting included with CFMX? Or must I purchase it separately?...
more >>
Tomcat 5 server and Flash Remoting
Posted by Stephen San Deigo at 10/8/2004 4:17:36 PM
Help, I am trying to get Flash Remoting working on our Tomcat 5 server. I can get the examples running only when the url is set to localhost. If I change it to the correct url it no longer functions. I read that you need the frconfig.txt file in order for it to work anywhere else beside...
more >>
Connected to gateway, makes call but no return
Posted by mattarm at 10/8/2004 12:58:10 AM
I have a very strange problem happening when I migrate an application from an stageing server to the clients server. I have migrated the files and can run the application from the authoring environment using the CFC's on the clients server - all works fine. Once I try to use the files on t...
more >>
How to pass a structure to a CFC???
Posted by SteveSt at 10/7/2004 9:46:38 PM
I have a cfc that requires a structure to be passed in: <cffunction name="getContracts" output="true" returnType="struct" access="remote"> <cfargument name="structContracts" type="struct" required="yes"> <cfset var tReturnValue = structNew() <cfset tReturnValue.bSuccess = true> <...
more >>
Flash can't call ColdFusion Component using CF Ma
Posted by DARAB at 10/7/2004 2:12:21 AM
I need to connect to a ColdFusion Component from Flash (2004). Every thing is working fine if I use the <web folder>dot<ColdFusion Component Name> syntax. When I use a ColdFusion mapping locally or remotely, nothing happens. When I use the mapping locally and run the Netconnection Debugger...
more >>
Using J2EE Back End - What is DataGrid Expecting?
Posted by TiredOne at 10/6/2004 9:15:32 PM
I have MX 2004 and have loaded the remoting for AS2. I am trying to retrieve an ArrayList into a DataGrid. Flash gets to the java server and successfully executes the retrieval, but when the ArrayList comes back into the remoting connector, it is an array of empty objects (as seen in debugger)...
more >>
remoting not working in mx 2004
Posted by folerf at 10/6/2004 2:48:37 PM
I have been working with remoting in mx, but when i try the same exact code in mx2004 it won't work. did anyone have any similar experiences? any suggestions how to get it to work? thanks...
more >>
AS 2.0 Classes not installed?
Posted by Silverline at 10/6/2004 11:29:12 AM
Hello, I am using Flash Remoting to connect to a dotnet assembly, but I think the AS 2.0 classes are not being installed on my computer, even though the AS 2.0 classes installer completes successfully. After installing the classes directory contains a folder called "remoting", but that fol...
more >>
How is Flash Remoting installed
Posted by hasanali00 at 10/6/2004 9:12:40 AM
Hi I tried to look for this answer on the website, but could not find one. My question is: if I buy Flash Remoting. where is it installed. Is it installed on a web server, or on a local machine. If it is installed on a web server, would I have a problem installing it on a shared hostin...
more >>
JUST GET ME CONNECTED
Posted by stebennettsjb at 10/5/2004 3:02:40 PM
Hi, i've been making a website using cfcs flash remoting (on mx 2004) it works great on my home computer using coldfusion developers edition... Now i want to put it up on site... i have coldfusion web space and put all files up as they where on my computer, nothing... i emailed my hosting ...
more >>
Returning ASObject in Flash/.NET remoting
Posted by KVdS at 10/5/2004 12:11:18 PM
I've written a small test-class in C#: using System; using System.IO; using System.Collections; using FlashGateway.IO; namespace FlashRemoting.FlashTest { public class TestClass { public TestClass() { } public ASObject GetAnObj() { ASObject aso = new ASOb...
more >>
openAMF
Posted by neosamz at 10/5/2004 8:30:38 AM
I am a beginner in Java and Flash. Could anyone give me a "hello world" sample using openAMF from java project into flash presentation? This sample will help me to start and I'm really appreciate for the help. Please send it to [email protected]. Thank you. ...
more >>
CFC Trouble
Posted by Course Vector at 10/5/2004 4:05:12 AM
I created a CFC that lists directories and jpgs. I can target it using a normal coldfusion file and it works fine. The CFC is located at the root in a folder named "remoting" .cfm code: <cfoutput> <cfinvoke component="remoting.getDir" method="getList" directory="" returnVariable="me...
more >>
pass arguments using remoting component
Posted by ultimateCF at 10/5/2004 12:31:46 AM
Is it possible to do the following, and if so how? Using the remoting component pass a variable as an argument to my cfc....
more >>
Flash Remoting with very large databases?
Posted by Saywell at 10/4/2004 8:42:34 PM
I am very interested in utilising Flash remoting, to redevelop my company?s system. I would like users to access and administer our databases using flash as a front end, as I see enormous potential for it to be a complete all encompassing office solution. I have very little idea of the...
more >>
java pagedResultSet problem
Posted by killjoy_tr at 10/4/2004 11:10:42 AM
Hello, I've been trying to make use of PagedResultSet created in a servlet the way below; Connection connection = getConnection("oracle_map"); Statement statement = connection.createStatement (ResultSet.TYPE_SCROLL_INSENSITIVE, ...
more >>
Can Flash remote access CFM SESSION?
Posted by Jeremy Tan at 10/3/2004 11:34:57 AM
Hi everyone, I am new to Flash. I am thinking to convert a HTML ColdFusion Application to Flash version, In the HTML Version, I am keeping most of the user login details in SESSION, how can I do this in flash if want to re-use the existing code. ...
more >>
google search and flash SWFs
Posted by animathor at 10/1/2004 4:06:10 AM
Hello, We have a flash enhanced site, completely built with flash, with lots of text content embedded in the flash swfs. But, we want to make sure that google can index our content! google can't search swfs properly. There are issues with timelines and levels trying to link to a s...
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n | http://www.developmentnow.com/g/72_2004_10_0_0_0/macromedia-flash-flash-remoting.htm | crawl-001 | refinedweb | 2,853 | 73.17 |
(Uche 2000-05-02)
XMLDocument?'s builder does not currently support validation.
In fact, it is a low-level handler for pyexpat which doesn't
support validation.
One nice benefit of using 4DOM would be that DTD validation
support comes along for the ride. Now it is important to note
that DTD validation is pretty broken in some areas, such as
namespaces, and very limited in some areas as data-typing, but
it does have its uses, and more importanly, its strong adherents
in the XML community.
For one thing, it would allow the use of parsed general entities
(this allows a mechanism not unlike macro-expansion), unparsed
general entities and notations (which allow inclusion of external
non-XML data such as images) and of course, document validation.
It is also important to establish a framework for validation so that
once the XML Schema spec is complete, it will be easy to add such
support (note that some parties are already working on schema
validators in Python). Other schema methodologies such as
Schematron and RELAX. Should be
considered as options.
The good news is that 4DOM currently uses SAX for reading, which
allows us to use xmlproc, a validating parser.
There is also the matter of specifyingthe schema.
Schemas are specified in the document-type declaration (note,
different from DTD=document-type definition) as follows:
<?xml version="1.0"?>
<!DOCTYPE ADDRBOOK SYSTEM "addrschema.dtd" PUBLIC "">
Note thet the "PUBLIC" part is optional, but with the above
we can simply read the schema from the given URL. Most
validating XML parsers already do this.
There is also a mechanism for locating resources referenced
in SYSTEM identifiers: XCatalog?. 4DOM's reader already supports
XCatalog? through xmlproc.
It might be useful to also add an attribute to XMLDocument? objects
with their schema. This would allow more flexible
validation-on-the-fly and would enable alternative schemas
not supported by xmlproc, such as XML schemas, Schematron and RELAX. | http://old.zope.org/Members/jim/ZDOM-save/DocumentValidation/wikipage_view | CC-MAIN-2014-15 | refinedweb | 324 | 55.95 |
I'm starting now using python and I want to create a weather script. Then I'll put that script working with a 16x2 LCD, but that will be easy.
Moving on... I picked up a python program already made by raspberrypi-spy that used to work with Google API. Since google closed that API support I'd seached for another one and found Foreca.
I've managed to put it working with the script, but the problem is that the script is only made to show the temperature and I also want to show the weather condition (Overcast, Clear, Rain, etc) and I can't put this working...
So, the script I've picked up is here. Is the weather_lcd.py file.
And my code is this one:
- Code: Select all
# Getting weather stats
import urllib2
import re
weatherURL1 = ""
response1 = urllib2.urlopen(weatherURL1)
html1 = response1.read()
#print html
r_temp = re.compile("tf=\"[0-9]{1,3}\"")
r_cond = re.compile("sT=\"[A-Z]{1,20}\"")
temp_search = r_temp.search(html1)
cond_search = r_cond.search(html1)
if temp_search:
temp1 = temp_search.group(0)
temp1 = re.sub("\D", "", temp1)
print temp1+"ºC"
else:
print "no temp found"
if cond_search:
cond = cond_search.group(0)
cond = re.sub("\S", "", cond)
print cond
else:
print "no cond found"
Could anyone help me?
By the way (only one more thing), after this I'll want to have it showing a 3 day forecast from here but I also don't know how to search the info from different lines
Sorry for the very very long post. I only want to give you the most info I can. | https://www.raspberrypi.org/forums/viewtopic.php?t=25924&p=235877 | CC-MAIN-2015-22 | refinedweb | 268 | 85.18 |
iBATOR - Introduction
iBATOR is a code generator for iBATIS. iBATOR introspects one or more database tables and will generate iBATIS artifacts that can be used to access the table(s).
Later you can write your custom SQL code or stored procedure to meet yoru requirements. iBATOR generates following artifacts:
SqlMap XML Files
Java Classes to match the primary key and fields of the table(s)
DAO Classes that use the above objects (optional)
iBATOR can run as a standalone JAR file, or as an Ant task, or as an Eclipse plugin. This tutorial would teach you simplest way of generating iBATIS configuration files form command line.
Download iBATOR:
Download the standalone JAR if you are using an IDE other than Eclipse. The standalone JAR includes an Ant task to run iBATOR, or you can run iBATOR from the command line of from Java code.
You can download zip file from Download iBATOR.
You can check online documentation: iBATOR Documentation.
Generating Configuration File:
To get up and running quickly with Abator, follow these steps:
Step 1:
Create and fill out a configuration file ibatorConfig.xml appropriately. At a minimum, you must specify:
A <jdbcConnection> element to specify how to connect to the target database.
A <javaModelGenerator> element to specify target package and target project for generated Java model objects
A <sqlMapGenerator> element to specify target package and target project for generated SQL map files.
A <daoGenerator> element to specify target package and target project for generated DAO interfaces and classes (you may omit the <daoGenerator> element if you don't wish to generate DAOs).
At least one database <table> element
NOTE: See the XML Configuration File Reference page for an example of an Abator configuration file.
Step 2:
Save the file in some convenient location for example at: \temp\ibatorConfig.xml).
Step 3:
Now run Abator from the command line with a command line as follows:
java -jar abator.jar -configfile \temp\abatorConfig.xml -overwrite
This will tell Abator to run using your configuration file. It will also tell Abator to overwrite any existing Java files with the same name. If you want to save any existing Java files, then omit the -overwrite parameter.
If there is a conflict, Abator will save the newly generated file with a unique name.
After running Abator, you will need to create or modify the standard iBATIS configuration files to make use of your newly generated code. This is explained in next section.
Tasks After Running Abator:
After you run Abator, you will need to create or modify other iBATIS configuration artifacts. The main tasks are as follows:
Create or Modify the SqlMapConfig.xml file.
Create or modify the dao.xml file (only if using the iBATIS DAO Framework).
Each task is described in detail below:
Updating the SqlMapConfig.xml File:.
Abator specific needs in the configuration file are as follows:
Statement namespaces must be enabled.
Abator generated SQL Map XML files must be listed ..
Updating the dao.xml File:: This step is only required if you generated DAOs for the iBATIS DAO framework. | http://www.tutorialspoint.com/ibatis/ibator_introduction.htm | CC-MAIN-2014-42 | refinedweb | 509 | 55.74 |
.
Long ago, I proposed:
//////////////////////////////////////// int32_t sex(int32_t x) { // this relies on automagic promotion // (which is about the same as // (int32_t)((int16_t)x)) union { int64_t w; struct { int32_t lo, hi; }; // should be hi,lo on a big endian machine } z = { .w=x }; return z.hi; }
This should rely on some variant of movsx (move with sign extend), cdqe (convert double to quadword in accumulator, i.e., RAX), and a second move instruction to get the high part of the register into another register’s lower part. Well, nope. Disassembly (g++ -O3 ) reveals
400ed0: 48 63 c7 movsxd rax,edi 400ed3: 48 c1 f8 20 sar rax,0x20 400ed7: c3 ret
The compiler does a shift right of 32 positions to get to the higher part. So that’s basically the same as
int32_t sex_shift(int32_t x) { return (x>>31); }
neglecting the fact that it will overwrite/discard the argument. This disassembles to
400ef0: 89 f8 mov eax,edi 400ef2: c1 f8 1f sar eax,0x1f 400ef5: c3 ret
This variant just propagates the sign bit, using expected signed-shift behavior. On some CPU, that’s fine because the execution time of a shift doesn’t depend on the number of bits shifted, but on some other architecture, that might be n cycles per position shifted. That’d be pretty inefficient. So that got me thinking that there ought to be some other way to propagate the sign bit than using shift.
Using a bunch o’shifts like this:
int32_t sex_shift_3(int32_t x) { x&=0x80000000; x|=(x>>1); x|=(x>>2); x|=(x>>4); x|=(x>>8); // maybe some low-level x|=(x>>16); // byte-copy can help? return x; }
Uses a bunch of instructions, most of which are short shifts, some of which could be replaced by register-level movs instructions. This time the compiler doesn’t seem to know what to do with it:
400f00: 89 f8 mov eax,edi 400f02: 25 00 00 00 80 and eax,0x80000000 400f07: 89 c2 mov edx,eax 400f09: d1 fa sar edx,1 400f0b: 09 d0 or eax,edx 400f0d: 89 c2 mov edx,eax 400f0f: c1 fa 02 sar edx,0x2 400f12: 09 d0 or eax,edx 400f14: 89 c2 mov edx,eax 400f16: c1 fa 04 sar edx,0x4 400f19: 09 d0 or eax,edx 400f1b: 89 c2 mov edx,eax 400f1d: c1 fa 08 sar edx,0x8 400f20: 09 d0 or eax,edx 400f22: 89 c2 mov edx,eax 400f24: c1 fa 10 sar edx,0x10 400f27: 09 d0 or eax,edx 400f29: c3 ret
So that’s not that good, is it? We’re not heading in the right direction at all. Let’s see what else we can do:
int32_t sex_shift_4(int32_t x) { return ~((x<0)-1); }
This sets a value, exactly 0 if x<0 is false, and exactly 1 if it is true. If it is true, ~(1-1)=~0=0xff..ff, if it is false, ~(0-1)=~(-1)=~0xff..ff=0. That’s what we want. However, this disassemble to…
400f30: 89 f8 mov eax,edi 400f32: c1 f8 1f sar eax,0x1f 400f35: c3 ret
Oh g*d d*ammit!
*
* *
This is the perfect example of how “optimizations” are quite relative. relative to the underlying machine and to the compiler. While ~((x<0)-1) is branchless, and should rely on cute instructions like test and setcc, the compiler sees through it and replaces it by a shift. On my machine, that’s probably indeed much faster than the alternative, naïve, implementation of the same function. Oh well. Time well wasted, I guess. | https://hbfs.wordpress.com/2017/03/07/much-ado-about-nothing/ | CC-MAIN-2017-13 | refinedweb | 599 | 66.37 |
![if gte IE 9]><![endif]>
Just setting the stage here...I am not a 4GL expert but was trying to show our developers how to use background threads in VB.NET to use animated images on forms.
So I created a Progress .NET form with a button and put this code in the click event so that the foreground thread would be busy..to show that animated images need their own thread or that the processing needed to be a separate worker thread from the form.
def variable i as integer init 0. pictPleaseWait:Visible = true. lblStart:Text = STRING(NOW). process events.
do while i < 999999999 :
i = i + 1.
end.
pictPleaseWait:Visible = false. lblEnd:Text = STRING(NOW). RETURN.
Now here is the code on my vb.net form with code behind on click event.
Dim i As Integer = 0 lblStart.Text = Now.ToLongTimeString
pictPleaseWait.Visible = True
Application.DoEvents()
Do While i < 999999999
i = i + 1
Loop
pictPleaseWait.Visible = False lblEnd.Text = Now.ToLongTimeString
The progress code takes minutes to run...the vb code takes seconds....
Any idea why?
Thanks,
Scott
The Core Client team is committed to supporting and enhancing the ABL, which includes improving the performance of the language.
The team has discussed the use of LLVM several times in the past and although we have not moved forward with a project which leverages this technology we are not opposed to integrating newer technologies into the product. However, each project needs to be evaluated against the other projects which PM identifies as a priority for a release.
From time to time an example is posted to Community which highlights the performance other languages vs. the ABL. We will continue to review these situations and if we determine there is a real benefit to the ABL we will investigate optimizing the Language.
We have investigated and are continuing to analyze our OOABL infrastructure, looking for optimizations we can make. When optimizations can be safely made, we implement these changes.
The point of this thread is to identify that runtime performance is important and in that, there is agreement. Working with PM, this development effort must be prioritized with the team’s other development tasks.
Evan Bleicher
Sr. Development Manager
Progress Software
Sorry that this has turned into two completely unrelated conversations. But re post above by swilson-musco:
Process-events is in the trigger to allow the main form to enable the .NET picture box with an animated gif.
I thought you said the animation was happening in another thread. So why do you need to be processing events on this main UI thread to make it work? Besides, you were JUST in a WAIT-FOR, processing events, before this trigger code ran.
I still don't get why progress completely ignores the ABL performance.
Having a runtime language without JIT or any kind of optimization in 2017 is just madness.
This case just proves that they don't even target the "easy" optimizations.
This is because every time this kind of questions pop up some says that once you hit the database that will be much slower anyway, therefor concluding that the 4GL performance doesn't matter. For what it's worth, I strongly disagree with this...
Architect of the SmartComponent Library and WinKit
Consultingwerk Ltd.
doa:
> Having a runtime language without JIT or any kind of optimization in 2017 is just madness.
Mike Fechner:
> Me to. ABL performance matters!!!!!!!!!!!
Which kinds of optimizations would give the best value for the investment in time and money?
Is there any quick way of adding JIT, which would fit within the company's available resources, and would remain portable to all platforms?
Oh, and btw, ABL performance is important as well because when it performs good it gives more bang for your bucks on the server. In OpenEdge it is highly beneficial to have your appserver next to the database (shared mem), and the more efficient the ABL is, the more I can run on the the same server before I have to scale out/up.
Every optimization would matter, this has to be a continuous process.
I guess the best (but completely unrealistic) case would be if the port the ABL to something like LLVM.
But yeah...i have no hope that any singificant things will change here.
moving the ABL to llvm would be a huge task.
much of the code is in the runtime anyway.
that said, there are quite a few worthwhile performance improvements that could be made to the 4GL interpreter.
as with any other improvement, what gets done or not done is all a matter of priorities.
go to the PUG Challenge in Manchester NH tomorrow. Pester Evan.
I sometimes wonder why PSC does little compiler ptimizations. Is it because it's to risky?
> This case just proves that they don't even target the "easy" optimizations.
I don't think so.Time of DO loop on the same box per Progress version:
Time(ns) Progress
149 11.6
159 10.2B
477 10.1C
444 10.0A
660 9.1B
878 8.3A
8,610 7.3C (VM)
> On Jun 3, 2017, at 5:42 PM, onnodehaan wrote:
>
> I sometimes wonder why PSC does little optimizations. Is it because it's to risky?
it is a question of on what are the most important things to spend the finite developer time.
go to the PUG Challenge and pester Evan Bleicher.
I appreciate the answers given..my intent was not to ruffle any feathers..just trying to learn and understand. As stated earlier, I am not a 4GL expert. My job is more of a DBA/Architect role and when developers come to me as say "Doing X or Y is slow" generally the first reaction is we need more hardware or faster storage. Just trying to understand that perhaps the solution isn't to spend more money or build a better mouse trap but consider other language alternatives to get the job done without having to invest a new system design. The Progress DB supports many ways to get to the database, making sure developers are aware of the strengths and weakness of 4GL may influence them on which language will help them get the task done in the least amount of time.
Thank you for your time.
I think that OpenEdge has many good features but the language itself is too slow.I raised often the same problem, objects are slow, simple I = I + 1 and string concatenation is a catastrophe.
I am working in a mixed team, my colleagues are using C# and they are using the cpu power, I can't.ABL GUI is useful for displaying data, some calculation but the rest has to be done on the appserver.If you need hardware support you are forced to write assemblies in C# because they are using multi-threading.
Years ago, as I used OEA the first time (10.2A in Paris), I can't get Mikes presentation out of my head where he was so happy that OE has now a possibility to resize windows and a useful flow control, I head the first contact with the bridge.10.2A was very painful and with 10.2B it made sense to use it.
During this time I joined a German PUG meeting and a member company presented a fully new developed solution based on ABL.NET.
I had the chance to join one year later the next meeting again and we got the same presentation, only with the latest output after one year developing time.
But what happend?!
I noticed that they buried ABL in the frontend and switched to C#, only the background was still using the "big ABL experience", that was the main point for the frontend last year too.I asked them what happened and I was told: They realized that a modern concept wasn't possible because the UI was too slow and had limitations.
If nothing will change it looks like that ABL UI could be a dead end in this kind of implementation.
It's nice to have the ability to use the same code from lightyears ago, this was still the killer argument.But meanwhile UI changed in windows to WPF, none of my colleagues is using winforms anymore.I don't think that WPF will be introduced in ABL, but perhaps it will be buried too like Silverlight and HTML5 and winforms are still there?
I think that Progress could make a hard break to something new without 100% compatibility with old code.Make something new with a new compiler.
Another option could be something like integrating OE into MS VisualStudio and provide a good and easy data and appserver access. Deliver an entity framework OE database provider and a ABL compatibility class like MS did with the first VB.NET version to help users to convert old VB6 code into the new world of .NETThen we could switch to C# with all language components.
It could be that I wrote nonsense but when I understood Mikes comment correct, the client is only fast with data when using datasets and temp-table.
My colleagues do not use this technology anymore since entity frameworks are available.It's not perfect but objects are much better in the UI and compatible to every control and with ABL a performance nightmare.
My 2 cents.
I tried a development tool to write a program in "VB6 like" syntax and run it in its IDE using JAVA 8 JDK. If this development approach can be applied to ABL, I can use ABL to write programs and make use of JAVA runtime. | https://community.progress.com/community_groups/openedge_development/f/19/t/33862?pi20882=2 | CC-MAIN-2018-30 | refinedweb | 1,614 | 73.88 |
Macroeconomic and
Foreign Exchange
Policies of Major
Trading Partners of the
United States
U.S. DEPARTMENT OF THE TREASURY
OFFICE OF INTERNATIONAL AFFAIRS
October 2018
Contents
EXECUTIVE SUMMARY ......................................................................................................................... 1
SECTION 1: GLOBAL ECONOMIC AND EXTERNAL DEVELOPMENTS ..................................... 8
U.S. ECONOMIC TRENDS ....................................................................................................................................... 8
INTERNATIONAL ECONOMIC TRENDS ............................................................................................................... 11
ECONOMIC DEVELOPMENTS IN SELECTED MAJOR TRADING PARTNERS ...................................................... 17
SECTION 2: INTENSIFIED EVALUATION OF MAJOR TRADING PARTNERS ....................... 28
KEY CRITERIA ..................................................................................................................................................... 28
SUMMARY OF FINDINGS ..................................................................................................................................... 30
GLOSSARY OF KEY TERMS IN THE REPORT ............................................................................... 32
This Report reviews developments in international economic and exchange rate policies
and is submitted pursuant to the Omnibus Trade and Competitiveness Act of 1988, 22
U.S.C. § 5305, and Section 701 of the Trade Facilitation and Trade Enforcement Act of 2015,
19 U.S.C. § 4421. 1
1 The Treasury Department has consulted with the Board of Governors of the Federal Reserve System and
International Monetary Fund (IMF) management and staff in preparing this Report.
Executive Summary
Global growth in 2018 has become less even and broad-based than it was amidst the
synchronized upswing last year. The United States remains a bright spot in the global
economy, with growth having accelerated in the second quarter, but there are signals that
economic activity may be slowing in other key regions (the euro area; China) while many
emerging markets have come under pressure from rebounding commodity prices, rising
interest rates, and shifts in sentiment. The Administration’s economic reform efforts –
including tax reform, ongoing regulatory initiatives, and major new trade agreements – are
bearing fruit, as business investment in the United States has accelerated and the outlook
for median income growth is strong. Restoring broad-based growth across the global
economy would be helped by economies putting in place reforms that enhance the
efficiency of tax systems, upgrade regulatory frameworks to better support domestic
investment, and support sound monetary policies.
Real exchange rate movements in 2018 have not generally been in a direction that would
promote more balanced global growth. Most notably, the recent strengthening of the dollar
and the decline in China’s currency would, if sustained, exacerbate persistent trade and
current account imbalances. In March, all G-20 members agreed that strong fundamentals,
sound policies, and a resilient international monetary system are essential to the stability
of exchange rates, contributing to strong and sustainable growth and investment. It is
important that major economies pursue this vision more vigorously. Treasury will also be
monitoring closely the extent to which intervention by our trading partners in foreign
exchange markets is symmetrical, and whether economies that choose to “smooth”
exchange rate movements resist depreciation pressure in the same manner as appreciation
pressure.
The U.S. trade deficit has continued to widen in 2018, partly reflecting robust domestic
demand growth in the United States compared to major trading partners, but also due to
persistent trade and investment barriers in many economies, along with sustained
undervaluation of many currencies per assessments by the International Monetary Fund
(IMF). Bilateral trade deficits with several major trading partners are at very high levels,
particularly with China. Moreover, current account surpluses among several major trading
partners have remained excessive for many years.
The Administration remains deeply concerned by the significant trade imbalances in the
global economy, and is working actively across a broad range of areas to help ensure that
trade expands in a balanced way that protects U.S. firms and workers against unfair foreign
trade practices. The United States is committed to working towards a fairer and more
reciprocal trading relationship with China.
The United States is also committed to combatting unfair currency practices that facilitate
competitive advantage, including unwarranted intervention in currency markets. Among
major U.S. trading partners, Korea announced this year that it would begin reporting
publicly on foreign exchange intervention in early 2019. We welcome this important
development in Korea’s foreign exchange practices. In addition, in the context of trade
1
negotiations, Mexico, Canada, and the United States have agreed to incorporate
commitments into the U.S.-Mexico-Canada trade agreement to avoid unfair currency
practices and confirm ongoing transparency on related information. We will consider
adding similar concepts to future U.S. trade agreements, as appropriate.
Treasury also continues to press major trading partners of the United States that have
maintained large and persistent external surpluses to support stronger and more balanced
global growth by facilitating domestic demand growth as the primary engine for economic
expansion.
Treasury Analysis Under the 1988 and 2015 Legislation
Since 1988, the Treasury Department has been issuing reports to Congress that analyze
international economic policies, including exchange rate policies, of the major trading
partners of the United States. Two pieces of U.S. legislation govern the content of these
reports.
The Omnibus Trade and Competitiveness Act of 1988 (the “1988 Act”) requires the
Secretary of the Treasury to provide semiannual reports to Congress on international
economic and exchange rate policy. Under Section 3004 of the 1988 Act, the Secretary
must:
“consider whether countries manipulate the rate of exchange between their currency
and the United States dollar for purposes of preventing effective balance of payments
adjustment or gaining unfair competitive advantage in international trade.”
This determination is subject to a broad range of factors, including not only trade and
current account imbalances and foreign exchange intervention (criteria under the second
piece of legislation discussed below), but also currency developments, exchange rate
practices, foreign exchange reserve coverage, capital controls, and monetary policy.
The Trade Facilitation and Trade Enforcement Act of 2015 (the “2015 Act”) calls for the
Secretary to monitor the macroeconomic and currency policies of major trading partners
and engage in enhanced analysis of those partners if they trigger certain objective criteria
that provide insight into possibly unfair currency practices.
Treasury has established thresholds for the three criteria as follows: (1) a significant
bilateral trade surplus with the United States is one that is at least $20 billion; 2
2 Given data limitations, Treasury focuses in this Report on trade in goods, not including services.
The United
States has a surplus in services trade with many economies in this report, including Canada, China, Japan,
Korea, Mexico, Switzerland, and the United Kingdom. Taking into account services trade would reduce the
bilateral trade surplus of these economies with the United States.
2
12-month period. 3 In 2017, the $20 billion bilateral trade surplus threshold captured
almost 80 percent of the value of all trade surpluses with the United States, while the 3
percent current account threshold captured more than three-fourths of the nominal value
of global current account surpluses.
China has a long history of pursuing a variety of economic and regulatory policies that lead
to a competitive advantage in international trade, including through facilitating the
undervaluation of the renminbi (RMB). The Treasury Department cited China for
manipulating its currency regularly between 1992 and 1994, noting China’s continued
reliance on foreign exchange restrictions that limited Chinese imports. In January 1994,
China devalued its currency by 33 percent, from 5.82 RMB to the dollar to 8.72. China then
fixed its exchange rate at 8.28 for a decade until 2005, a level that was deeply undervalued.
Notwithstanding its constructive decision not to further devalue its currency during the
1997-98 Asian Financial Crisis, China’s insistence on maintaining the RMB exchange rate at
a highly undervalued level for such an extended period of time created strong economic
incentives to artificially increase the size of China’s export sector, just as it negotiated its
entry into the World Trade Organization in 2001.
Subsequently, even as its trade and current account surpluses soared, China undertook
protracted, large-scale intervention in the foreign exchange market and allowed the RMB to
strengthen only gradually. Chinese net purchases of foreign exchange averaged almost
nine percent of GDP annually from 2002 to 2009, building excess reserves that eventually
reached about $4 trillion. Importantly, China’s current account surplus expanded from
below 2 percent of GDP in 2001 to a peak of almost 10 percent of GDP in 2007..
Thus, since the 1988 Act was passed, China’s exchange rate and intervention practices
promoted and sustained a significant undervaluation of the RMB for much of this period,
imposing significant and long-lasting hardship on American workers and companies.
Over the last decade, the RMB has generally appreciated on a real, trade-weighted basis.
This appreciation has led the IMF to shift its assessment of the RMB in recent years and
conclude that the RMB is broadly in line with economic fundamentals. Notwithstanding
this gradual real trade-weighted appreciation, on a bilateral basis RMB depreciation in the
last few months has brought the RMB back to where it stood against the dollar in nominal
terms almost a decade ago.
3.
3
Moreover, in the last couple of years, China has shifted from a policy of gradual economic
liberalization to one of reinforcing state control and increasing reliance on non-market
mechanisms. The pervasive use of explicit and implicit subsidies and other unfair practices
are increasingly distorting China’s economic relationship with its trading partners. These
actions tend to limit Chinese demand for and market access to imported goods, leading to a
wider trade surplus. China’s policies also inhibit foreign investment, contributing to
weakness in the RMB.
Of concern, the RMB has fallen notably in recent months. Since mid-June, the RMB has
depreciated to date against the dollar by more than 7 percent. The RMB has also fallen by
nearly 6 percent over the same period versus a broad trade-weighted basket of currencies.
The majority of depreciation against the dollar occurred between mid-June and mid-
August; from mid-August through end-September, the RMB remained within a relatively
narrow range of 6.8-6.9 RMB to the dollar. This depreciation of the RMB will likely
exacerbate China’s large bilateral trade surplus with the United States, as well as its overall
trade surplus.
While China’s exchange rate practices continue to lack transparency, including its
intervention in foreign exchange markets and its management of daily central parity
settings to influence the value of the RMB, Treasury estimates that direct intervention by
the People’s Bank of China (PBOC) this year has been limited. Since the summer, the
Chinese authorities have reportedly employed limited tools to stem depreciation pressures,
including implementing administrative measures and influencing daily central parity
exchange rate levels. Broader proxies for intervention indicate there have been modest
foreign exchange sales recently by state banks, helping stem depreciation pressures,
though it is clear that China is not resisting depreciation through intervention as it had in
the recent past.
Treasury Conclusions Related to China
Based on the analysis in this Report, Treasury determines, pursuant to the 2015 Act,
that China continues to warrant placement on the Monitoring List of economies that
merit close attention to their currency practices. Treasury determines.
• China continues to run an extremely large and persistent bilateral trade surplus with
the United States, by far the largest among any of the United States’ major trading
partners, with the goods trade surplus standing at $390 billion over the four quarters
through June 2018. As discussed above, recent depreciation of the RMB will likely
exacerbate China’s large bilateral trade surplus with the United States, as well as its
overall trade surplus. Treasury places significant importance on China adhering to its
G-20 commitments to refrain from engaging in competitive devaluation and to not
target China’s exchange rate for competitive purposes. China could pursue more
4
market-based economic reforms that would bolster confidence in the RMB. Treasury
continues to urge China to enhance the transparency of China’s exchange rate and
reserve management operations and goals. Treasury is deeply disappointed that China
continues to refrain from disclosing its foreign exchange intervention. Finally, to
enhance the sustainability of both Chinese and global growth, China needs to
aggressively advance reforms that support greater household consumption growth and
rebalance the economy away from investment.
Treasury Conclusions Related to Other Major Trading Partners
Pursuant to the 2015 Act, Treasury has found in this Report that no major trading
partner met all three criteria during the four quarters ending June 2018. Similarly,
based on the analysis in this Report, Treasury also concludes that no major trading
partner of the United States met the standards identified in Section 3004 of the 1988
Act.
Regarding the 2015 legislation, Treasury has established a Monitoring List of major trading
partners that merit close attention to their currency practices and macroeconomic policies.
An economy meeting two of the three criteria in the 2015 Act is placed on the Monitoring
List. Once on the Monitoring List, an economy will remain there for at least two
consecutive Reports to help ensure that any improvement in performance versus the
criteria is durable and is not due to temporary factors. As a further measure, this
Administration will add and retain on the Monitoring List any major trading partner that
accounts for a large and disproportionate share of the overall U.S. trade deficit even if that
economy has not met two of the three criteria from the 2015 Act. In this Report, in
addition to China, the Monitoring List comprises Japan, Korea, India, Germany, and
Switzerland.
With regard to the other five economies on the Monitoring List:
• Japan maintains the third-largest bilateral goods trade surplus with the United States,
with a goods surplus of $70 billion over the four quarters through June 2018. Japan’s
current account surplus over the four quarters through June 2018 was 4.0 percent of
GDP, close to its highest level in a decade. Japan has not intervened in the foreign
exchange market in almost seven years. Treasury’s expectation is that in large, freely-
traded exchange markets, intervention should be reserved only for very exceptional
circumstances with appropriate prior consultations. Japan should take advantage of the
current window of steady growth to enact critical structural reforms that can support
sustained faster expansion of domestic activity, create a more sustainable path for long-
term growth, and help reduce Japan’s public debt burden and trade imbalances.
• Korea has for many years maintained an excessively strong external position, though
there has been some moderation in its external imbalances recently. Korea’s goods
trade surplus with the United States continued to narrow to $21 billion over four
quarters through June 2018, contracting over $7 billion from its peak level in 2015.
Korea’s current account surplus also narrowed slightly over the four quarters through
5
June 2018 to 4.6 percent of GDP. The won appreciated 7 percent against the dollar over
the second half of 2017, but much of this move has reversed in 2018. There was a
notable and concerning pick-up in foreign exchange intervention in November 2017
and January 2018 that appears to have been for the purpose of slowing won
appreciation against the dollar. These purchases were partially reversed through net
foreign exchange sales in the first half of 2018 as the won depreciated against the
dollar. The IMF continues to describe Korea’s current account surplus as larger, and its
exchange rate as weaker, than justified by medium-term economic fundamentals.
Further, despite real effective appreciation over four quarters through June 2018 of 2
percent, the won is not notably strong compared to levels it has been over the last
couple decades. It is important that the Korean authorities act to strengthen domestic
demand; recent fiscal policy proposals would be a step in the right direction, but Korea
maintains ample policy space to more forcefully support demand growth. Treasury will
continue to monitor closely Korea’s currency practices, including the authorities’
recently announced plans to increase the transparency of exchange rate intervention.
• India’s circumstances have shifted markedly, as the central bank’s net sales of foreign
exchange over the first six months of 2018 led net purchases over the four quarters
through June 2018 to fall to $4 billion, or 0.2 percent of GDP. This represented a
notable change from 2017, when purchases over the first three quarters of the year
pushed net purchases of foreign exchange above 2 percent of GDP., but India’s current account is in deficit at 1.9 percent of
GDP. As a result, India now only meets one of the three criteria from the 2015 Act. If
this remains the case at the time of its next Report, Treasury would remove India from
the Monitoring List.
•. As it now stands, these surpluses represent a
substantial excess of income over spending, which translates into weaker imports by
Germany than could be, and thus very large capital outflows. Germany should take
policy steps to unleash domestic investment and consumption – including meaningful
fiscal reforms to minimize burdens from elevated labor and value-added taxes – which
would narrow the gap between domestic income and spending and help reduce large
6
external imbalances. The European Central Bank (ECB) has not intervened unilaterally
in foreign currency markets in over 15 years. 4
• Switzerland’s foreign exchange purchases have declined markedly in both scale and
persistence since mid-2017. This has come as economic conditions have also shifted:
inflation in Switzerland has turned positive, domestic economic activity has picked up,
and pressures from safe haven inflows have been less persistent. Treasury estimates
that net purchases of foreign exchange over the four quarters through June 2018
totaled $17 billion, equivalent to 2.4 percent of GDP, with purchases occurring less
frequently than in prior years. The Swiss franc appreciated modestly in both nominal
and real effective terms over the first half of 2018; however, the real effective exchange
rate remains less than 6 percent above its 20-year average level. Switzerland had a
very large current account surplus at 10.2 percent of GDP over the four quarters
through June 2018. To help narrow the large and persistent trade and current account
surpluses, Switzerland should adjust macroeconomic policies to more forcefully
support domestic economic activity. Treasury also urges the Swiss authorities to
enhance the transparency of exchange rate intervention.
Treasury continues to track carefully the foreign exchange and macroeconomic policies of
our trading partners under the requirements of both the 1988 and 2015 Acts, and to
review the number of economies covered in this Report.
4 For the purposes of Section 701 of the 2015 Act, policies of the ECB, which holds responsibility for monetary
policy for the euro area, will be assessed as the monetary authority of individual euro area countries.
7
Section 1: Global Economic and External Developments
This Report covers economic, trade, and exchange rate developments for the first six
months of 2018 and, where data are available, developments through end-September 2018.
This Report covers developments in the 12 largest trading partners of the United States, as
well as Switzerland, which is currently the United States’ 15th largest trading partner. 5
These economies’ total goods trade with the United States amounted to $2.9 trillion over
the four quarters through June 2018, over 70 percent of all U.S. goods trade during that
period. For some parts of the analysis, especially those parts having to do with Section 701
of the 2015 Act, data over the most recent four quarters for which data are available are
considered (typically up through the second quarter of 2018).
U.S. Economic Trends
The U.S. economic expansion accelerated markedly in the first half of 2018, growing at an
annual rate of 3.2 percent, compared with 2.6 percent in the second half of last year.
Growth of private domestic final demand remained strong in the first half of this year,
rising by 3.1 percent, compared with a rate of 3.3 percent in the latter half of 2017, while
net exports picked up, contributing positively to growth.
The underpinnings of growth have improved thus far in 2018, and include a faster pace of
job creation, strong labor markets with rising labor force participation, multi-year highs in
measures of consumer and small business confidence, solid household finances, and the
strongest outlook for business activity and private investment in many years. Further, the
effects of tax reform appear to be feeding through into the economy, with business fixed
investment growing strongly over the first half of the year. These factors boosted private
domestic demand to a 4.3 percent pace in the second quarter of 2018. Inflation (headline
as well as core, which excludes food and energy) continued to tick up but remained
moderate, and interest rates, including mortgage rates, also moved up. As of early October
2018, a consensus of private forecasters predicted that real GDP would expand at a rate of
3.1 percent in 2018.
Recent U.S. Growth Performance
Real GDP expanded at an average annual rate of 3.2 percent over the first half of 2018
2017, accelerating noticeably from the 2.6 percent rate in the second half of the year.
Domestic final demand remained firm, and after reaching its fastest pace in three years in
the final quarter of 2017 (4.4 percent), rebounded to 4.3 percent at an annual rate in the
second quarter of 2018. Consumer spending contributed 1.5 percentage points to GDP
growth in the first half of 2018, less than the 2.1 percentage points added in the latter half
of 2017. Business fixed investment added 1.3 percentage points to growth in the first half
of this year, nearly triple the 0.5 percentage point contribution made in the latter half of
5 Switzerland is included in this Report as it has previously appeared on Treasury’s Monitoring List since the
October 2016 Report.
8
last year. After making a modest, 0.2 percentage point contribution to growth in the
second half of 2017, residential investment subtracted 0.1 percentage point over the first
half of this year. Net exports added 0.6 percentage point to growth in the first half of 2018,
after posing a drag on growth of 0.4 percentage point in the latter half of 2017. Inventory
accumulation added 0.1 percentage point to growth during last year’s second half, but
subtracted 0.4 percentage point from growth in the first two quarters of this year.
Government spending boosted growth by 0.1 percentage point in the second half of 2017,
and by 0.3 percentage point in the first half of 2018.
Sound Fundamentals
Payroll employment growth accelerated in 2018, after growing at an already-firm pace
throughout 2017, and as of September 2018 the unemployment rate had declined to a 49-
year low. Nonfarm payroll employment added 208,000 jobs per month, on average, over
the first nine months of 2018, stepping up from the 182,000 average monthly pace in 2017.
In September the unemployment rate declined to 3.7 percent, the lowest rate since 1969.
Other measures of labor market conditions continue to improve: there are signs of faster
growth in wages, and broader measures of unemployment continue to trend lower.
Measures of consumer mood are at, or very near, multi-year highs according to recent
surveys, with households continuing to express positive views about current and future
economic conditions. Compensation growth continues to firm on a gradual basis: average
hourly earnings for production and nonsupervisory workers rose 2.7 percent over the
twelve months through September 2018, faster than the 2.6 percent, year-earlier pace, and
also stepping up from the rates that prevailed from 2011 through 2015. Total
compensation costs for civilian workers advanced 2.8 percent over the four quarters
ending in June 2018, 0.5 percentage point higher than the year-earlier pace. Moreover, the
debt-service ratio facing households is near historical lows, and household net worth
stands at a record high.
Business activity and investment have continued to accelerate this year, building on last
year’s solid gains. According to the most recent survey of the Institute for Supply
Management (ISM) in September, the composite index for the manufacturing sector
signaled brisk growth, standing just below the 14-year high reached in August. Fifteen of
18 industries reported expansion, while only three industries reported contraction. The
ISM’s non-manufacturing index also pointed to faster expansion in the services sector in
September, climbing to its highest level in over 20 years. After several weak quarters in
2015 and early 2016, business fixed investment has firmed noticeably over the past
eighteen months, rising by 10.1 percent during the first half of 2018, after growing by 4.1
percent in the latter half of 2017 and by 8.4 percent during last year’s first half.
Although headline inflation continues to accelerate, it remains moderate by historical
standards. The consumer price index (CPI) for all items rose 2.3 percent over the twelve
months through September 2018, faster than the 2.2 percent rate seen over the year
through September 2017. Growth in the core CPI (which excludes food and energy prices)
9
moved up to 2.2 percent over the year through September 2018, above the 1.7 percent rate
seen over the year through September 2017.
Fiscal Policy and Public Finances
In December 2017, the United States enacted the first major re-write of the U.S. tax code in
three decades. The new tax code is designed to markedly strengthen incentives for
business investment and to deliver tax relief to middle income households. The new tax
law lowered the U.S. corporate tax rate from one of the highest in the developed world to
near the average of other advanced economies; it allows businesses to immediately deduct
100 percent of the cost of most of their new capital investments for the next five years; and
it delivers relief to working families through lower income tax rates, a larger standard
deduction, and an expanded child tax credit. Combined with regulatory reforms and
infrastructure initiatives, tax reform is expected to encourage people to start new
businesses, draw more workers into the labor market, and support a sustained increase in
productivity.
The Administration estimates that in FY 2018 the federal government budget deficit was
$779 billion (3.9 percent of GDP), up from $666 billion (3.5 percent of GDP) in FY 2017.
Under the Administration’s budget proposals, the federal deficit over the next five years
(FYs 2019 to 2023) would total $5.1 trillion (4.4 percent of GDP on average). However, the
Administration expects that implementation of its budget proposals – including cuts to
non-defense discretionary spending, elimination of the Affordable Care Act, and reform of
multiple welfare programs – would gradually decrease the deficit to $539 billion (1.6
percent of GDP) by FY 2028. The Administration expects debt held by the public to rise
from an estimated 78 percent of GDP ($15.8 trillion) in FY 2018 to a peak near 83 percent
of GDP in FY 2022, before gradually declining to 75 percent of GDP by FY 2028.
U.S. Current Account and Trade Balances
The U.S. current account was in deficit by 2.2 percent of GDP in the first half of 2018,
broadly similar to its level in the second half of 2017 and slightly narrower than the 2.4
percent of GDP current account deficit over the same period a year earlier. While the goods
trade deficit has expanded U.S. Current Account Balance
slightly in nominal terms Income Services Goods Current Account Balance
(increasing $26 billion in the 3
first half of 2018 compared 2
Percent of GDP
1
to the same period a year 0
earlier), it has been -1
relatively steady as a share -2
of GDP. The wider goods -3
deficit has also been partly -4
-5
offset by a small rise in the
H1 2011
H2 2011
H1 2012
H2 2012
H1 2013
H2 2013
H1 2014
H2 2014
H1 2015
H2 2015
H1 2016
H2 2016
H1 2017
H2 2017
H1 2018
services trade surplus (up
$10 billion year-over-year in
the first half of 2018). Sources: Bureau of Economic Analysis, Haver
10
After narrowing in the post- U.S. Goods Balance
crisis era to just below 2 0
percent of GDP in the second -1
half of 2013, the headline
-2
Percent of GDP
U.S. current account deficit
has been quite stable since -3
2015 in the ballpark of 2–2½ -4
percent of GDP. Similarly,
-5
the goods trade balance has Non-Oil Balance
been relatively stable in -6
Oil Balance
recent years, in the range of -7
4–4½ percent of GDP. But 2006 2008 2010 2012 2014 2016 2018
significant shifts have Source: Bureau of Economic Analysis
occurred within the goods balance. The U.S. petroleum deficit has fallen to its lowest level
in decades and has been steadily below 0.5 percent of GDP since the second half of 2015 as
domestic production has expanded, compressing net petroleum imports. The non-oil
goods deficit, by comparison, has been widening and now stands close to 4 percent of GDP.
In general over the last few years, the widening non-oil goods deficit reflected strong
import growth and relatively stagnant export growth, likely an effect of the broad
strengthening of the dollar from mid-2014 to early 2017 alongside relatively stronger
domestic demand growth in the United States compared to major trading partners in
recent years. This picture has shifted slightly in 2018, however: while goods imports have
continued to expand, U.S. goods exports have picked up in recent quarters, with non-oil
goods exports more than 7 percent higher year-over-year in the first half of 2018.
At the end of the second quarter of 2018, the U.S. net international investment position
stood at a deficit of $8.6 trillion (42.3 percent of GDP), a deterioration of more than $900
billion compared to end-2017. The value of U.S.-owned foreign assets was $27.1 trillion,
while the value of foreign-owned U.S. assets stood at $35.7 trillion. Recent deterioration in
the net position has been due in part to valuation effects from an appreciating dollar that
lowered the dollar value of U.S. assets held abroad, as well as the relative
underperformance of foreign equity markets compared to U.S. stock markets in 2018.
International Economic Trends
After a synchronized upswing across the global economy in 2017, global growth has
become more uneven and less broad-based over the first half of 2018. Growth in advanced
economies outside the United States has generally disappointed, with output growth across
the euro area, Japan, and the United Kingdom stepping down from its 2017 level. Among
emerging markets, both China and India continue to expand robustly, though in China there
are signals that real activity may be slowing. Many other emerging markets, meanwhile,
have come under pressure as rebounding commodity prices, rising U.S. interest rates, and
shifts in investor sentiment have interacted with preexisting weaknesses and led to bouts
of financial volatility, weighing on growth prospects. According to the IMF’s October 2018
WEO, global growth is expected to be broadly stable at 3.7 percent over 2018 and 2019,
similar its 2017 level. However, the outlook for several key advanced and emerging market
11
economies has been marked GDP Growth
down, and risks are tilted to the 9
Percent change (annualized rate)
downside as uncertainty and 2017
recent lackluster growth among 6
H1 2018
several large economies
suppress medium-term 3
prospects.
0
India
Canada
Italy
France
Japan
Brazil
China
Mexico
Taiwan
UK
Korea
United States
Switzerland
Germany
Foreign Exchange Markets
The U.S. dollar appreciated 5.6
percent on a nominal effective
Note: H1 2018 for China and India based off Q2/Q2 NSA data.
basis over the first three Sources: National Authorities, Haver
quarters of 2018, retracing most
of its decline over 2017 and
U.S. Dollar vs. Major Trading Partner Currencies
approaching its peak levels in (+ denotes dollar appreciation)
the post-crisis period. The dollar Korea
has strengthened broadly Euro H2 2017
Canada
against a variety of advanced UK Q1-Q3 2018
economy and emerging market Taiwan
Japan
currencies. Notably, the China
Brazilian real, pound sterling, Switzerland
Mexico
renminbi, and euro faced sizable India
depreciation vis-à-vis the dollar Brazil
amidst uncertainty surrounding -10 0 10 20 30
the Brazilian economic outlook, Percent change (relative to end-June 2017)
Source: FRB
Brexit, U.S.-China trade-related
risks, and flagging European growth signals. Strong U.S. growth and the divergence in
monetary policy of major economies also has played a role in currency movements, as
relatively higher interest rates in the United States have attracted capital flows and put
upward pressure on the dollar.
Of concern, the dollar is strengthening at a time when the IMF judges that the dollar is
moderately overvalued on a real effective basis. Over the first three quarters of 2018, the
dollar appreciated by 4.7 percent in real effective terms and now stands around 6 percent
above its 20-year average. Continued dollar strength would likely exacerbate persistent
trade and current account imbalances.
Notwithstanding recent broad dollar strength, a few key currencies have strengthened in
nominal effective and real effective terms due to appreciation relative to their non-U.S.
trading partners. Most notably, the euro has risen on a real effective basis in 2018 in a
manner that helps correct for the undervaluation the IMF assessed for 2017. However,
aside from the euro, real effective exchange rates across the United States’ major trading
partners have generally not moved in a direction that corrects for pre-existing
misalignments.
12
IMF Estimates of Exchange Rate Misalignment
2017 REER Misalignment (mid)¹ 2018 REER ∆²
20
CA Deficit Economies CA Surplus Economies
Overvalued
10
Percent
0
-10
Undervalued
-20
India
U.K.
Euro Area
Canada
Italy
France
Japan
Brazil
Mexico
China
Korea
United States
Switzerland
Germany
Sources: IMF 2018 External Sector Report, BIS REER Indices, and FRB
1/The IMF's estimate of real effective exchange rate (REER) misalignment (expressed as a range) compares
the country's average REER in 2017 to the level consistent with the country's medium-term economic
fundamentals and desired policies. The midpoint of the misalignment range is depicted above.
2/Change through August 2018 versus 2017 average.
Note: The IMF does not provide an estimate of Taiwan's REER misalignment.
Treasury judges that foreign exchange markets have continued to function smoothly in
recent months, including as the Federal Reserve raised its interest rate corridor (in March,
June, and September this year) and continued reducing the size of its balance sheet. The
dollar continues to be the world’s principal currency in international foreign exchange
markets, reflecting its dominant global position both in terms of market turnover (being
bought or sold in 88 percent of all currency trades) and trade settlement. 6
Global Imbalances
Global current account imbalances remain large. Imbalances narrowed slightly to 1.8
percent of global GDP in 2017, but from a historical perspective, imbalances had not
reached 2 percent of global GDP prior to 2000. Persistent and concentrated imbalances
have characterized the post-crisis landscape, particularly in the surplus economies of Asia
and northern Europe. In part, this has reflected a rotation of surpluses from oil exporting
economies (as global energy prices fell) into oil-importing industrial economies. The
persistence of imbalances has also reflected relative real exchange rates – as noted in the
previous section – with the dollar being relatively strong in historical terms since mid-
2014.
6 Currency market turnover according to the 2016 Bank for International Settlement Triennial Central Bank
Survey of Foreign Exchange and OTC Derivatives.
13
Global Current Account Imbalances
China Germany Japan
Other Surplus United States Other Deficit
4 Statistical Discrepancy
3
2
Percent of Global GDP
1
0
-1
-2
-3
-4
1980
1982
1984
1986
1988
1990
1992
1994
1996
1998
2000
2002
2004
2006
2008
2010
2012
2014
2016
Sources: IMF WEO, Haver
Global Current Account Balances - Adjustment 2015Q2-2018Q2
(rolling 4Q sum)
5
Shrinking CA Deficit
Growing CA Surplus
3-Year Change in Balance (% of GDP)
4
Brazil
3
Japan
Taiwan
UK Mexico France
2
1
United States Italy Switzerland
0
-10 -5 0 5 10 15
-1
Germany
Canada -2
India
Growing CA Deficit -3
China Korea
Shrinking CA Surplus
2018Q2 Current Account Balance (% of GDP)
Sources: Haver, IMF WEO, National Authorities
Note: Size of bubble is relative to share of global imbalances
Over the last three years, the majority of the United States’ major trading partners have
seen current account imbalances widen – as has the United States – though there are some
exceptions. China’s current account surplus has narrowed markedly, though its
merchandise trade surplus remains large and researchers have raised questions about
measurement issues that could cause the reported current account balance to be
understated. Korea’s surplus has also narrowed somewhat from recent peak levels. But
14
several European economies, as well as Japan and Taiwan, have seen external surpluses
grow.
Imbalances have been sustained by the asymmetric composition of growth across key
economies: Asian and European economies, where persistent surpluses are concentrated,
relied heavily on positive contributions from net exports to drive growth between 2010
and 2015. More recently, gross capital formation in several of these economies has been
stagnant with no downward adjustment to national saving, particularly in Germany, Japan,
and Switzerland. Growth in North and Latin America since the crisis, by comparison, has
been led by domestic demand, with the strengthening of U.S. demand being central to the
recent global growth uptick. In order to reduce the risk of a future adjustment in external
balances that weighs on global growth, major economies must put in place a more
symmetric rebalancing process that entails all economies carrying a share of the
adjustment.
Capital Flows
Financial turbulence in key Net Capital Flows to Emerging Markets
600 EM excluding China China
emerging market economies
in 2018 had broader 400
spillovers and – coupled with 200
rising U.S. interest rates that
USD Billions
0
attracted capital flows into
the United States – led -200
foreign portfolio flows to -400
emerging markets (excluding -600
China) to fall off over the first
-800
half of 2018, with flows
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
YTD 2018
turning negative in the
second quarter. Higher Note: Financial account (excluding reserves) adjusted for errors and ommissions.
2018 reflects data through the first two quarters where available.
frequency data (from sources Source: National Authorities, U.S. Department of the Treasury Staff Calculations
beyond quarterly balance of
payments data) suggest that economies with relatively weak domestic fundamentals have
experienced the largest and most sustained foreign portfolio outflows, particularly of
portfolio debt. During the first two quarters of 2018, net portfolio flows in emerging
markets (ex-China) totaled -$114 billion (based on data available through mid-October),
declining by about $176 billion relative to the same period in 2017, with several emerging
markets experiencing sustained portfolio outflows. Foreign direct investment to emerging
markets, on the other hand, remained stable and positive in 2018, effectively
counterbalancing net portfolio outflows. Overall, net capital flows to emerging markets
(ex-China) were slightly positive, as in 2017, well below the levels typically witnessed a few
years ago.
In China, stronger-than-expected domestic growth, tighter capital controls, and a more
balanced renminbi outlook helped stem resident outflows while boosting foreign inflows
during 2017, reversing a two-year trend of sizable net capital outflows. Since end-2017,
15
domestic outflows have remained relatively modest while foreign direct and nonresident
portfolio investment flows continue to pick up. Relative to the same period last year, net
portfolio flows for the first two quarters increased by $91 billion, while net direct
investment increased by $66 billion.
Foreign Exchange Reserves
Global foreign currency reserves Change in Foreign Currency Reserves
have been broadly stable this H2 2017 H1 2018
Canada
year, with headline reserves Germany
now close to $11.5 trillion, up Italy
$41 billion over the first half of Mexico
Brazil
the year. After valuation
UK
changes pushed up headline Japan
reserve levels in the second half France
of 2017, the rise in the dollar in Taiwan
2018 has weighed on the dollar India
Korea
value of global reserve stocks, Switzerland
with some net reserve China
accumulation over the first half World
of 2018 acting to keep headline -100 0 100 200 300 400
reserves rising slightly. The Note: Includes valuation effects USD Billions
increase in global reserves over Sources: International Monetary Fund, Haver (Cumulative change)
the last year continues to
reverse the $1.3 trillion decline in Table 1: Foreign Exchange Reserves
reserves witnessed between mid- FX Reserves
2014 and the end of 2016 that was FX Reserves FX Reserves (months of
associated with many economies’ (% of GDP) (% of ST debt) imports)
reserve asset sales to stem or slow Switzerland 107% 68% 24.3
local currency depreciation. Taiwan 78% 257% 16.9
Korea 24% 324% 7.9
The economies covered in this Japan 24% 42% 16.7
China 23% 279% 16.1
Report continue to maintain ample
Brazil 18% 606% 19.4
– or more than ample – foreign India 14% 373% 7.9
currency reserves compared to Mexico 14% 331% 4.3
standard adequacy benchmarks. UK 4% 2% 1.8
Reserves in most economies are Canada 4% 11% 1.5
more than sufficient to cover short- Italy 2% 4% 0.8
term external liabilities and France 2% 2% 0.7
anticipated import costs. Excessive Germany 1% 2% 0.3
reserve accumulation imposes Foreign exchange reserves as of Jun 2018.
costs both on the local economy (in Sum of rolling 4Q GDP through Q2-2018.
Short-term debt consists of gross external debt with original
terms of sterilization costs and
maturity of one year or less, as of the end of Q1-2018.
foregone domestic investment) and
Sum of rolling 4Q imports of goods and services through Q1-2018.
the world. Economies should focus Sources: National Authorities, World Bank, IMF
on enhancing resilience through
16
stronger policy frameworks, as recommended by the IMF, rather than through continued
reserve accumulation. 7
Economic Developments in Selected Major Trading Partners
China
China’s trade surplus with the United States continues to be the largest trade imbalance
across the United States’ major trading partners, with the goods trade surplus growing to a
record level of $390 billion over the four quarters through June 2018. While U.S. goods
exports to China have risen (to $135 billion over the four quarters through June 2018, up
$12 billion from the same period 12 months prior), goods imports have increased more (up
$45 billion year-over-year to $525 billion over the four quarters through June 2018). The
U.S. services trade surplus with China held steady near $20 billion over the first half of
2018, after totaling $40 billion in 2017.
Treasury remains deeply concerned by this excessive trade imbalance which is
exacerbated by persistent non-tariff barriers, widespread non-market mechanisms, the
pervasive use of subsidies, and other unfair practices which increasingly distort China’s
economic relationship with its trading partners. Treasury urges China to create a more
level and reciprocal playing field for American workers and firms, implement
macroeconomic reforms that support greater consumption growth, reduce the role of state
intervention, and allow a greater role for market forces. It is in China’s interest to
implement measures that would reduce the bilateral trade imbalance.
Recent movements in China’s China: Exchange Rates
currency have not been in a CFETS Bilateral vs. USD
direction that will help reduce
Indexed December 2014 = 100
106
China’s large trade surplus.
102
Since mid-June, the RMB has
weakened more than 7 percent 98
versus the dollar and close to 6
94
percent against the CFETS
nominal basket. Treasury staff 90
estimate China’s direct
86
intervention in the foreign
Dec-14 Jun-15 Dec-15 Jun-16 Dec-16 Jun-17 Dec-17 Jun-18
exchange market to have been Sources: CFETS, Bloomberg
limited this year, including in
recent months when the RMB was depreciating. After accounting for valuation effects,
Treasury staff estimate net foreign exchange intervention by the People’s Bank of China
(PBOC) to be effectively neutral year-to-date. Broader measures that proxy for
intervention suggest that foreign exchange purchases by financial entities beyond PBOC –
7 International Monetary Fund, 2011, “Assessing Reserve Adequacy,” IMF Policy Paper, February
(Washington: International Monetary Fund).
17
notably state banks – increased in April and May, totaling close to $45 billion in the second
quarter. Since the summer, authorities have reportedly used a few different tools to stem
depreciation pressures including implementing administrative measures and influencing
daily central parity exchange rate levels, including through reintroduction of a
countercyclical adjustment
factor. Alternatively, Treasury China: Estimated FX Intervention
Preferred Methodology* Bank FX Settlement
staff estimate that the PBOC has 50
refrained from intervention to
Billion U.S. Dollars
0
counter depreciation pressures.
The same broader measure that -50
indicated foreign exchange was
-100
purchased by entities beyond
PBOC in the second quarter -150
showed that there were foreign
Oct-15
Oct-16
Oct-17
Jan-15
Jul-15
Jan-16
Jul-16
Jan-17
Jul-17
Jan-18
Jul-18
Apr-15
Apr-16
Apr-17
Apr-18
exchange sales of around $10
billion by the same set of entities Sources: PBOC, SAFE, U.S. Treasury Estimates
in August. *Based on change in FX-denominated assets on PBOC balance sheet
Treasury continues to place considerable importance on China adhering to its G-20
commitments to refrain from engaging in competitive devaluation and to not target China’s
exchange rate for competitive purposes. Treasury also strongly urges China to provide
greater transparency of its exchange rate and reserve management operations and goals.
China’s overall balance of China: Current Account Balance
Income Services Goods Current Account Balance
payments situation has generally
10
stabilized since the second half
of last year, with foreign
Percent of GDP
exchange reserves steadying (at 5
around $3.1 trillion), and
financial and capital outflows 0
slowing. Recent RMB
depreciation has not been
-5
accompanied by capital outflow
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018H1
pressures, which have fallen
substantially this year compared Sources: SAFE, Haver
to the period from late 2015 to early 2017. Treasury estimates that, in the first half of this
year, net outflows (excluding flows accounted for by trade and direct investment) totaled
around $10 billion, markedly lower than $160 billion in the first half of 2017 or the $290
billion in the year prior. This moderation in net Chinese resident capital outflows was
aided by relatively tighter capital control measures, in addition to an uptick of inflows into
Chinese financial assets. Nonetheless, the persistent presence of sizeable net errors and
omissions, which have been negative for seventeen consecutive quarters, could suggest
continued undocumented capital outflows. Meanwhile, China’s current account surplus
18
over the four quarters through June 2018 totaled $68 billion, with a large goods surplus
continuing to offset deficits in the services trade and the income balance. 8
High-frequency indicators suggest economic activity has decelerated in 2018 as authorities
have pursued the needed deleveraging campaign to address financial stability risks.
Officially reported real GDP growth fell slightly to 6.7 percent in the second quarter
compared to 6.8 percent in the first quarter on a year-over-year basis, with overall
consumption as the largest contributor. Going forward, structural reforms that durably
open China’s economy to U.S. goods and services, alongside efforts to reduce state
intervention, allow a greater role for market forces, and strengthen household
consumption growth would provide more opportunities for American firms and workers to
compete in Chinese markets and facilitate a more balanced economic relationship between
the United States and China.
Japan
Japan’s current account surplus Japan: Current Account Balance
Income Services Goods Current Account Balance
remained elevated over the four 6
quarters through June 2018 at
4.0 percent of GDP, up from a
Percent of GDP
3
surplus of 3.8 percent of GDP for
the same period 12 months
prior. The large current account 0
surplus continues to be driven
primarily by high net foreign -3
income, which accounted for
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018H1
over 90 percent of the overall
surplus in the first half of 2018. Sources: Bank of Japan, Ministry of Finance, Cabinet Office
Many past years of surpluses have produced sizable net foreign assets: Japan’s net
international investment position stood at 64 percent of GDP in 2017, the highest in the G-
7, and the IMF projects it will rise to 77 percent of GDP in the medium term, suggesting
sizable net foreign income flows for years to come. These foreign income flows are
potential spendable income that could be used to bolster demand growth and help reduce
Japan’s sizeable current account surplus.
Japan’s goods trade surplus with the United States over the four quarters through June
2018 was $70 billion, broadly stable relative to the same period 12 months prior. The
United States has a small surplus in services trade with Japan ($12 billion over the four
quarters though June 2018), offsetting a small portion of the large goods trade imbalance.
8There is evidence that China’s deficit in services trade has been overstated by as much as 1 percent of GDP,
with the actual current account balance being higher by a corresponding amount. See Wong, Anna (2017).
"China's Current Account: External Rebalancing or Capital Flight?" International Finance Discussion Papers
1208. Board of Governors of the Federal Reserve System (U.S.).
19
Treasury remains concerned by the persistence of the large bilateral trade imbalance
between the United States and Japan.
Safe-haven inflows amid Japan: Exchange Rates
heightened geopolitical tensions REER NEER Bilateral vs. USD
140 140
Indexed to 20Y Avg = 100
likely played a role in the 6.1
percent appreciation of the yen 120 120
versus the dollar from January
100 100
through end-March. From end-
March through mid-July the yen 80 80
depreciated around 6 percent
against the dollar, 60 60
Jan-07
Jan-08
Jan-09
Jan-10
Jan-11
Jan-12
Jan-13
Jan-14
Jan-15
Jan-16
Jan-17
Jan-18
predominantly reflecting broad
dollar appreciation over the
period. As of end-September, it Sources: Bank of Japan, Bank for International Settlements
stood 0.7 weaker against the dollar year-to date. On a real effective basis, the yen has been
relatively stable and remains near the historically weak levels it has hovered around since
the first half of 2013.
Japan publishes its foreign exchange intervention. Japan has not intervened in foreign
exchange markets since 2011.
After weak growth in Q4 2017 and Q1 2018, growth rebounded in Q2 2018 to 3.0 percent
annualized. Private final consumption and domestic fixed capital formation remain
volatile, while the growth impulse from net exports has declined relative to 2016 and 2017.
After peaking at 1.5 percent year-on-year in February, CPI inflation has moderated
somewhat, and stood at 1.3 percent year-on-year as of August. The Bank of Japan (BOJ) has
maintained a policy of “Quantitative and Qualitative Easing with Yield Curve Control” since
September 2016. The BOJ maintains the overnight policy rate at negative 10 basis points
and purchases Japanese Government Bonds so that the 10-year yield remains “around”
zero percent. In its July Monetary Policy meeting, the BOJ announced that it would increase
the flexibility of its asset purchase program, reduce the size of account balances subject to
negative interest rates, and allow more movement in the 10-year yield around its zero
percent target. It also provided forward guidance that “the Bank intends to maintain the
current extremely low levels of short- and long-term rates for an extended period of time”
citing the need to monitor economic developments, including the impact of the increase in
the consumption tax slated for 2019. Following this announcement, the BOJ purchased
$3.6 billion in 5- to 10-year Japanese government bonds to stem a selloff that saw the 10-
year yield touch an 18-month high of 0.15 percent.
Looking forward it will be important that the Japanese authorities continue with their
structural reform agenda to entrench stronger growth, while ensuring the sustainability of
public finances. In the context of the proposed consumption tax hike slated for fall of 2019,
the authorities should ensure the contemplated offsets will be sufficient in both magnitude
and design to sustain economic growth.
20
Korea
After peaking at close to 8 Korea: Current Account Balance
Income Services Goods Current Account Balance
percent of GDP in 2015, Korea’s 10
current account surplus has
been gradually narrowing,
Percent of GDP
5
reaching 4.2 percent of GDP in
the first half of 2018. The
decline in the current account 0
has been largely due to a
widening of Korea’s services -5
trade deficit. Korea’s overall
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018H1
goods trade surplus has also
moderated somewhat, though it Sources: Bank of Korea, Haver
remains high at around 7 percent of GDP. The IMF in its most recent analysis continued to
describe Korea’s current account surplus as moderately stronger than justified by
economic fundamentals.
Korea’s goods trade surplus with the United States stood at $21 billion over the four
quarters through June 2018, down from a peak of $28 billion in 2015. The United States
has a surplus in services trade with Korea, at $14 billion over the four quarters through
June 2018.
Korea does not yet publish its Korea: Estimated FX Intervention
foreign exchange market Est. Spot Market Intervention Change in Net Forward Book
10
intervention. Korean authorities
Billion U.S. Dollars
announced earlier this year that 5
they would begin disclosing
0
intervention data in early 2019.
Treasury estimates that between -5
July 2017 and June 2018 Korean
authorities made net purchases -10
Oct-16
Oct-17
Jan-16
Jul-16
Jan-17
Jul-17
Jan-18
Jul-18
Apr-16
Apr-17
Apr-18
of foreign exchange of $4.1
billion (0.3 percent of GDP),
including activity in the forward Sources: Bank of Korea, U.S. Treasury estimates
market. Net purchases were concentrated in November 2017 and January 2018 (around
$9 billion), a period when the won was appreciating both against the dollar and on a real
effective basis. Appreciation against the dollar reversed in January, and the won has
depreciated roughly 6 percent to date in 2018 against the dollar, while appreciating by 0.2
percent on a real effective basis as of August. Net intervention since January, meanwhile,
has been relatively modest, with a decline in the Bank of Korea’s net forward position
largely offset by estimated spot market purchases.
The IMF has considered the Korean won to be undervalued every year since 2010, and in
its most recent evaluation considered the won to be undervalued by 2-7 percent. Korea
has well-developed institutions and markets and should limit currency intervention to only
21
truly exceptional circumstances Korea: Exchange Rates
of disorderly market conditions. Bilateral vs. USD REER NEER
Korea maintains ample reserves 130 130
Indexed to 20Y Avg = 100
at $390 billion as of June 2018, 120 120
equal to more than three times 110 110
gross short-term external debt 100 100
and 24 percent of GDP. 90 90
Treasury will be closely 80 80
monitoring authorities’ plans to 70 70
begin reporting foreign
Jan-07
Jan-08
Jan-09
Jan-10
Jan-11
Jan-12
Jan-13
Jan-14
Jan-15
Jan-16
Jan-17
Jan-18
exchange intervention in a more
transparent and timely manner. Sources: Bank of Korea, Bank for International Settlements
Though Korea’s external position has adjusted somewhat since the peak of the current
account surplus in 2015, there remains scope for policy reforms that would support a more
durable strengthening of domestic demand. Korea was strongly reliant on external
demand in the first few years after the global financial crisis, with net exports accounting
for more than one-third of cumulative growth over 2011-2014. Domestic demand growth
has generally been stronger since 2015, averaging above 4 percent annually, though it
stepped down in the first half of 2018 and the outlook for domestic demand growth going
forward is also clouded by elevated household debt.
In order to decisively rebalance the economy and further reduce the still-large trade and
current account surpluses, Korea will need to have a sustained period in which domestic
growth exceeds overall GDP growth. Korea maintains sufficient policy space to support
domestic demand, particularly as public sector debt remains relatively low at around 40
percent of GDP. Recent policy proposals appear to be a step in the right direction: the
Korean authorities’ 2019 budget calls for a 9.7 percent increase in fiscal spending next
year, which would be the highest increase in a decade. Proposed expenditures would
enhance the social safety net through subsidies for hiring young and elderly workers and
initiatives to increase female employment and childcare. The impact of these measures
could be enhanced by extending their duration and better targeting them at those living
below the poverty line, while pairing them with more comprehensive labor market reforms
that reduce restrictions on laying off regular workers and incentivize hiring non-regular
workers. Structural fiscal reforms to support household consumption could also be
particularly helpful to raise domestic demand and avoid reliance on net exports to drive
growth going forward.
India
India’s current account deficit widened in the four quarters through June 2018 to 1.9
percent of GDP, following several years of narrowing from its 2012 peak. The current
account deficit has been driven by a large and persistent goods trade deficit, which has in
turn resulted from substantial gold and petroleum imports. The goods trade deficit has
widened out in the first half to 6.4 percent of GDP as oil prices have risen. The IMF projects
22
the current account deficit to be India: Current Account Balance
around 2.5 percent of GDP over Income Services Goods Current Account Balance
the medium term as domestic 10
demand strengthens further and 5
Percent of GDP
favorable growth prospects
0
support investment.
-5
India’s goods trade surplus with -10
the United States was $23 billion
-15
for the four quarters through
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018H1
June 2018. India also had a
small surplus in services trade Sources: Reserve Bank of India
with the United States of $4
billion over the same period. India’s exports to the United States are concentrated in
sectors that reflect India’s global specialization (notably pharmaceuticals and IT services),
while U.S. exports to India are dominated by key service trade categories, particularly
travel and higher education.
India has been exemplary in publishing its foreign exchange market intervention. The
Reserve Bank of India (RBI) has noted that the value of the rupee is broadly market-
determined, with intervention used only during “episodes of undue volatility.” 2 percent of GDP over 2017.
Foreign exchange purchases India: FX Intervention
Net Spot Market Intervention Change in Net Forward Book
generally declined in the second 15
half of 2017, and the RBI shifted
Billion U.S. Dollars
10
to selling foreign exchange in the 5
first half of 2018. Net purchases 0
of foreign exchange over the -5
past four quarters through June -10
totaled $4 billion (0.2 percent of -15
GDP), including activity in the
Oct-2016
Oct-2017
Jan-2016
Jul-2016
Jan-2017
Jul-2017
Jan-2018
Jul-2018
Apr-2016
Apr-2017
Apr-2018
forward market. Sales of foreign
exchange in the first half of this
year came in the context of Source: Reserve Bank of India
foreign portfolio outflows of $7 billion, as India experienced outflows (particularly of
foreign portfolio debt) that were witnessed across many emerging markets in the second
quarter. This mirrored the pattern of the last few years, in which intervention has typically
tracked institutional portfolio flows. India maintains ample reserves according to IMF
metrics for reserve adequacy, particularly given that India maintains some controls on both
inbound and outbound flows of private capital. As of June 2018, foreign currency reserves
23
stood at $380 billion, equal to India: Exchange Rates
3.7 times gross short-term Bilateral vs. USD REER NEER
external debt, 8 months of 130 130
Indexed to 20Y Avg = 100
import cover, and 14 percent of 120 120
GDP. 9 110 110
100 100
The rupee depreciated 7 percent 90 90
against the dollar in the first half 80 80
of the year, while the real 70 70
effective exchange rate also
Jan-07
Jan-08
Jan-09
Jan-10
Jan-11
Jan-12
Jan-13
Jan-14
Jan-15
Jan-16
Jan-17
Jan-18
reversed its general uptrend
from the last few years, Sources: Reserve Bank of India, Bank for International Settlements
depreciating by 4 percent. In its
most recent analysis, the IMF assessed the real effective exchange rate to be in line with
economic fundamentals. The RBI’s most recent annual report assessed the rupee to be
“closely aligned to its fair value over the long term.”
The Euro Area and Germany
Euro area GDP growth moderated this year after posting its strongest overall performance
in a decade in 2017, but the economy continues to exhibit broad-based output growth
across both countries and sectors. While the aggregate euro area output gap has been
narrowing, the cyclical positions of individual member economies within the currency
union remain divergent due to the legacies of the euro area crisis. Further, trend growth
also varies widely across member countries, due in part to structural differences that affect
competitiveness. These dynamics have weighed on the value of the euro, making the euro’s
exchange rate appear undervalued for some of the strongest-performing individual
member countries in the currency union (e.g., Germany).
The euro depreciated by 3.5 percent against the dollar year-to-date through the end of
August, but it has strengthened in 2018 on both a nominal effective and real effective basis,
by 3.5 percent and 2.6 percent, respectively. Recent movements leave the euro still on the
weaker side of longer-term trends: The euro is about 1 percent below its 20-year average
in real effective terms and around 4 percent weaker on a nominal bilateral basis against the
dollar versus its 20-year average. The weakness of the euro is a multi-year phenomenon,
spurred initially by concerns about the resilience of the monetary union in the midst of the
regional crisis and sustained more recently by monetary policy. The ECB’s quantitative
easing and negative interest rate policy opened a sizable gap in bond market yields
between the euro area and other advanced economies, which has contributed to the euro’s
weakness versus its historical level in recent years. The euro area’s improved economic
performance helped support the common currency in 2017, but downside growth
surprises and political uncertainty have weighed on the currency in recent months.
9Gross short-term external debt reflects external debt with remaining maturity of one year or less, as
reported by the Joint External Debt Hub.
24
The ECB publishes its foreign exchange intervention, and has not intervened unilaterally in
over 15 years.
Germany’s current account surplus has been the largest in the world in nominal terms
since 2016, standing at $329 billion over the four quarters through June 2018 (equivalent
to 8.2 percent of GDP). German economic policies supporting high domestic saving and low
consumption and investment have pushed up Germany’s current account surplus, with
lower oil prices also supporting the external position since 2014. Over the long run, there
has been a meaningful divergence between German domestic inflation and wage growth
and (faster) average euro area inflation and wage growth. This has contributed to a
general rise in Germany’s competitiveness vis-à-vis its euro area neighbors. However,
given the wide dispersion of economic performance across the euro area, the euro’s
nominal exchange rate has not tracked this rise in German competitiveness. Consistent
with this, the IMF estimates that Germany’s external position remains substantially
stronger than implied by economic fundamentals, and Germany’s real effective exchange
rate undervalued by 10-20 percent. Further, with other euro area member countries
implementing reforms to rebalance their economies and reduce external deficits, the
strength of Germany’s external position is impacting the external balance of the euro area
overall: The IMF for the first time this year assessed the euro area as a whole to have an
external position moderately stronger than the level implied by economic fundamentals.
A number of German economic policies have restrained domestic consumption and
investment, including elevated labor and value-added taxes and strict fiscal rules. Growth
was strongly supported by net exports for several years following the crisis, which led to a
substantial widening of the current account surplus. Since 2015, growth has been more
balanced, with German domestic demand largely accounting for growth over the last three
years. This has helped stall the growth in the current account surplus, but it has not been
sufficient to appreciably reduce external imbalances. Demand growth needs to accelerate
substantially for a sustained period for external rebalancing to proceed at a reasonable
pace, which would be supported by growth-friendly tax and other policy reforms.
Germany’s bilateral trade surplus with the United States is excessive and a matter of
significant concern. Treasury recognizes that Germany does not exercise its own monetary
policy and that the German economy continues to experience strong gains in employment.
Nevertheless, Germany has a responsibility as the fourth-largest economy globally and as
an economy with a very large external surplus to contribute to more balanced demand
growth and to more balanced trade flows. Allowing an increase in domestic demand
against relatively inelastic supply should help push up wages, domestic consumption,
relative prices against many other euro area members, and demand for imports; and higher
relative prices would help appreciate Germany’s undervalued real effective exchange rate.
This would contribute to both global and euro area rebalancing.
Switzerland
Prior to 2017, Switzerland had for several years received safe haven capital inflows amidst
deflationary price pressures and muted domestic economic activity. In this context, foreign
25
exchange intervention had been Switzerland: Estimated FX Intervention
used – alongside negative 70
interest rates – to contain 60
Billion U.S. Dollars
appreciation pressures and 50
combat deflation. Since mid- 40
2017, the picture has shifted 30
markedly: inflation in 20
Switzerland has turned positive, 10
domestic economic activity has 0
Q1-2015
Q2-2015
Q3-2015
Q4-2015
Q1-2016
Q2-2016
Q3-2016
Q4-2016
Q1-2017
Q2-2017
Q3-2017
Q4-2017
Q1-2018
Q2-2018
accelerated, and pressures from
safe haven inflows have been
less persistent. In line with Sources: SNB, Haver, U.S. Treasury estimates based on sight deposits
these developments, foreign
exchange intervention has declined notably, in both scale and frequency. The Swiss
National Bank (SNB) does not report foreign exchange intervention outside of a yearly total
in its annual report. Based on sight deposit data, Treasury estimates that net purchases of
foreign exchange over the four quarters through June 2018 were relatively limited, though
possibly slightly in excess of 2 percent of GDP. Moreover, foreign exchange purchases are
estimated to have been less frequent, particularly in 2018, compared to previous years.
Switzerland’s current account Switzerland: Current Account Balance
Income Services Goods Current Account Balance
surplus remains elevated. The
15
current account surplus in the
first half of 2018 was 11.5 10
Percent of GDP
percent of GDP, up from 10.0 5
percent of GDP in the first half of
0
2017. The United States’ goods
trade deficit with Switzerland -5
was $17 billion over the four -10
quarters through June 2018, up
2008
2009
2010
2011
2012
2013
2014
2015
2016
2017
2018H1
from $13 billion compared to the
same period a year earlier. Sources: Swiss National Bank, Haver
The Swiss franc has appreciated year-to-date through the end of August, by 0.4 percent
against the dollar and 3.1 percent against the euro. Reflecting the euro’s greater
importance for Switzerland’s trade-weighted exchange rate, both the nominal and real
effective exchange rate (NEER and REER) appreciated over the same time period, by 3.9
percent and 3.4 percent, respectively, unwinding a portion of the decline over the latter
half of 2017. The depreciation of the franc over the second half of 2017 had led the SNB to
shift its assessment of the franc to “highly valued” – a characterization that maintained
through the first half of 2018. As of August 2018, the REER stood 5.5 percent above its 20-
year average.
As a result of interventions and valuation changes, foreign reserves had grown to $772
billion by the end of the first quarter 2018 (from $762 billion at end-2017) but declined
during the second quarter to $753 billion. This can be partly explained by a 4.1 percent
26
appreciation of the dollar against the Swiss franc during the second quarter. With inflation
now positive and safe haven pressures less persistent, the current window offers an
opportunity to consider how to unwind this large stock of foreign assets on the central
bank’s balance sheet. Further, given that external surpluses remain very large and the
acceleration in activity relatively nascent, Switzerland should adjust macroeconomic
policies to more forcefully support domestic economic activity. For example, Switzerland
appears to have ample fiscal space – with the budget broadly balanced and public debt
around 40 percent of GDP – and could pursue tax or other structural reforms aimed at
durably raising investment and productivity. Treasury continues to encourage the Swiss
authorities to transparently publish all intervention data on a higher frequency basis.
27
Section 2: Intensified Evaluation of Major Trading Partners
The Trade Facilitation and Trade Enforcement Act of 2015 (the “2015 Act”) requires the
Secretary of the Treasury to provide semiannual reports on the macroeconomic and
foreign exchange rate policies of the major trading partners of the United States. Section
701 of.” Additionally, the 2015 Act establishes a process to engage economies that may be
pursuing unfair practices and impose penalties on economies that fail to adopt appropriate
policies.
Key Criteria
Pursuant to Section 701 of the Trade Facilitation and Trade Enforcement Act of 2015, this
section of the Report (July 2017 to June 2018, unless
otherwise noted) are provided in Table 1 (on p. 16) and Table 2 (below).
As noted earlier, Treasury’s focus is on the 12 largest trading partners of the United States;
these economies account for more than 70 percent of U.S. trade in goods. Additionally, this
Report covers Switzerland, which is currently the United States’ 15th largest trading
partner, but has previously been among the 12 largest trading partners and has appeared
on Treasury’s Monitoring List. Treasury’s goal is to focus attention on those economies
whose bilateral trade is most significant to the U.S. economy and whose policies are the
most material for the global economy.
The results of Treasury’s latest assessment pursuant to Section 701 of the 2015 Act are
discussed below.
28
Table 2. Major Foreign Trading Partners Evaluation Criteria
Bilateral Trade Current Account Foreign Exchange Intervention
Goods Surplus with Balance 3 Year Change Balance Net Purchases Net Purchases Net Purchases Net Purchases
United States (USD (% of GDP, in Balance (USD Bil., (% of GDP, (USD Bil., (USD Bil., 8 of 12
Bil., Trailing 4Q) Trailing 4Q) (% of GDP) Trailing 4Q) Trailing 4Q) Trailing 4Q) Trailing 2Q) Months†
(1) (2a) (2b) (2c) (3a) (3b) (3c) (3d)
China 390 0.5 -2.3 68 0.0 1 6 Yes
Mexico 73 -1.6 0.3 -20 0.0 0 0 No
Japan 70 4.0 1.8 198 0.0 0 0 No
Germany 67 8.2 0.0 329 .. .. .. ..
Italy 32 2.8 1.0 57 .. .. .. ..
India 23 -1.9 -0.6 -50 0.2 4 -23 No
Korea 21 4.6 -2.3 73 0.3 4 -1 No
Taiwan 17 14.3 1.4 85 1.2 7 2 Yes
Switzerland 17 10.2 0.0 72 2.4 17 8 No
France 16 -0.6 -0.2 -16 .. .. .. ..
Canada 15 -3.1 0.0 -53 .. .. .. ..
United Kingdom -7 -3.5 1.5 -98 .. .. .. ..
Brazil -9 -0.7 3.5 -14 -2.0 -41 -39 No
Memo : Euro Area 143 3.6 0.7 486 0.0 0 0 No
Sources: U.S. Census Bureau; Haver Analytics; National Authorities; U.S. Department of the Treasury Staff Estimates
†In assessing the persistence of intervention, Treasury will consider an economy that is judged to have purchased foreign exchange on net for 8 of the 12 months to
have met the threshold.
Criterion (1) – Significant bilateral trade surplus with the United States:
Column 1 in Table 2 provides the Table 3. Major Foreign Trading Partners - Expanded Trade Data
Bilateral Trade
bilateral goods trade balances for Goods Surplus with Goods Trade Services Surplus with Services Trade
the United States’ 12 largest United States (USD (USD Bil., United States (USD (USD Bil.,
Bil., Trailing 4Q) Trailing 4Q) Bil., Trailing 4Q)* Trailing 4Q)*
trading partners and Switzerland (1a) (1b) (1c) (1d)
for the four quarters ending June China 390 660 -41 78
2018. 10 China has the largest Mexico
Japan
73
70
584
211
-8
-12
60
80
trade surplus with the United Germany 67 180 1 69
States by far, after which the sizes Italy 32 74 3 23
India 23 81 4 54
of the bilateral trade surpluses Korea 21 122 -14 36
decline notably. Treasury Taiwan 17 70 -1 18
Switzerland 17 61 n.a. n.a.
assesses that economies with a France 16 87 -2 38
bilateral goods surplus of at least Canada 15 604 -27 95
$20 billion (roughly 0.1 percent of United
Brazil
Kingdom -7
-9
119
69
-13
-21
131
35
U.S. GDP) have a “significant” Memo : Euro Area 143 589 n.a. n.a.
Source: U.S. Census Bureau, Bureau of Economic Analysis
surplus. Highlighted in red in *Services data is through Q2 2018. Services data is reported on a balance of payments basis (not
column 1 are the seven major seasonally adjusted), while goods data is reported on a census basis (not seasonablly adjusted).
Bilateral services trade data through Q2 2018 is not yet available for some trading partners.
trading partners that have a
bilateral surplus that meets this threshold over the most recent four quarters. Table 3
provides additional contextual information where available on bilateral services trade with
these trading partners.
10 Although this Report does not treat the euro area itself as a major trading partner for the purposes of the
2015 Act – this Report assesses euro area countries individually – data for the euro area are presented in
Table 2 and elsewhere in this Report both for comparative and contextual purposes, and because policies of
the ECB, which holds responsibility for monetary policy for the euro area, will be assessed as the monetary
authority of individual euro area countries.
29
Criterion (2) – Material current account surplus:
Treasury assesses current account surpluses in excess of 3 percent of GDP to be “material”
for the purposes of enhanced analysis. Highlighted in red in column 2a of Table 2 are the
five economies that had a current account surplus in excess of 3 percent of GDP for the four
quarters ending June 2018. In the aggregate, these five economies accounted for more than
half of the value of global current account surpluses as of the end of 2017. Column 2b
shows the change in the current account surplus as a share of GDP over the last three years,
although this is not a criterion for enhanced analysis.
Criterion (3) – Persistent, one-sided intervention:
Treasury assesses net purchases of foreign currency, conducted repeatedly, totaling in
excess of 2 percent of an economy’s GDP over a period of 12 months to be persistent, one-
sided intervention. 11 Columns 3a and 3d in Table 2 provide Treasury’s assessment of this
criterion. 12 In economies where foreign exchange interventions are not published,
Treasury uses estimates of net purchases of foreign currency to proxy for intervention. No
economy meets this criterion for the four quarters ending June 2018, per Treasury
estimates. 13
Summary of Findings
Pursuant to the 2015 Act, 14 Treasury finds that no major trading partner of the United
States met all three criteria in the current reporting period. Five major trading partners of
the United States, however, met two of the three criteria for enhanced analysis in this
Report or in the April 2018
11 Notably, this quantitative threshold is sufficient to meet the criterion.
Other patterns of intervention, with
lesser amounts or less frequent interventions, might also meet the criterion depending on the circumstances
of the intervention.
12 Treasury uses publicly available data for intervention on foreign asset purchases by authorities, or
estimated intervention based on valuation-adjusted foreign exchange reserves. This methodology requires
assumptions about both the currency and asset composition of reserves in order to isolate returns on assets
held in reserves and currency valuation moves from actual purchases and sales, including estimations of
transactions in foreign exchange derivatives markets. Treasury also uses alternative data series when they
provide a more accurate picture of foreign exchange balances, such as China’s monthly reporting of net
foreign assets on the PBOC’s balance sheet and Taiwan’s reporting of net foreign assets at its central bank. To
the extent the assumptions made do not reflect the true composition of reserves, estimates may overstate or
understate intervention. Treasury strongly encourages those economies in this Report that do not currently
release data on foreign exchange intervention to do so.
13 While Switzerland’s net purchases of foreign exchange are estimated at above 2 percent of GDP, there has
been a notable decline in the frequency and persistence of intervention.
14 Section 701 of the Trade Facilitation and Trade Enforcement Act of 2015, 19 U.S.C. § 4421.
30
material current account surpluses combined with significant bilateral trade surpluses
with the United States. Switzerland met two of the three criteria in every Report between
October 2016 and April 2018 – having a material current account surplus and having
engaged in persistent, one-sided intervention in foreign exchange markets – and it met one
of the three criteria in this Report, a material current account surplus. India met two of the
three criteria in the April 2018 Report – having a significant bilateral surplus with the
United States and having engaged in persistent, one-sided intervention in foreign exchange
markets – and it met one of the three criteria in this Report, a significant bilateral surplus
with the United States. In both Switzerland and India, there has been a notable decline
recently in the scale and frequency of foreign exchange purchases. Both Switzerland and
India must demonstrate that this improvement against the intervention criteria is durable
before they will be removed from the Monitoring List. China has met one of the three
criteria in every Report since the October 2016 Report, having a significant bilateral trade
surplus with the United States, with this surplus accounting for a disproportionate share of
the overall U.S. trade deficit. Treasury will closely monitor and assess the economic
trends and foreign exchange policies of each of these economies.
Further, based on the analysis in this Report, Treasury has also concluded that no major
trading partner of the United States met the standard in the 1988 Act of manipulating the
rate of exchange between its currency and the United States dollar for purposes of
preventing effective balance of payments adjustments or gaining unfair competitive
advantage in international trade during the period covered in the Report.
Notwithstanding these findings, Treasury remains deeply concerned by the significant
trade imbalances in the global economy. Real exchange rate movements in 2018 –
particularly the strengthening of the dollar and the decline in China’s currency – would, if
sustained, exacerbate persistent trade and current account imbalances. China’s economic
model, which continues to rely significantly on non-market mechanisms, is posing growing
risks to the long-term global growth outlook. The United States is committed to working
towards a fairer and more reciprocal trading relationship with China. To this end, we are
engaging China to address its market-distorting policies and practices. Treasury also
continues to press major trading partners of the United States that have maintained large
and persistent external surpluses to support stronger and more balanced global growth by
facilitating domestic demand growth as the primary engine for economic expansion.
31
Glossary of Key Terms in the Report
Exchange Rate – The price at which one currency can be exchanged for another. Also
referred to as the bilateral exchange rate.
Exchange Rate Regime –The manner or rules under which an economy manages the
exchange rate of its currency, particularly the extent to which it intervenes in the foreign
exchange market. Exchange rate regimes range from floating to pegged.
Floating (Flexible) Exchange Rate – An exchange rate regime under which the foreign
exchange rate of a currency is fully determined by the market with intervention from the
government or central bank being used sparingly.
Foreign Exchange Reserves – Foreign assets held by the central bank that can be used to
finance the balance of payments and for intervention in the exchange market. Foreign
assets consist of gold, Special Drawing Rights (SDRs), and foreign currency (most of which
is held in short-term government securities). The latter are used for intervention in the
foreign exchange markets.
Intervention – The purchase or sale of an economy’s currency in the foreign exchange
market by a government entity (typically a central bank) in order to influence its exchange
rate. Purchases involve the exchange of an economy’s own currency for a foreign currency,
increasing its foreign currency reserves. Sales involve the exchange of an economy’s
foreign currency reserves for its own currency, reducing foreign currency reserves.
Interventions may be sterilized or unsterilized.
Nominal Effective Exchange Rate (NEER) – A measure of the overall value of an
economy’s currency relative to a set of other currencies. The effective exchange rate is an
index calculated as a weighted average of bilateral exchange rates. The weight given to
each economy’s currency in the index typically reflects the amount of trade with that
economy.
Pegged (Fixed) Exchange Rate – An exchange rate regime under which an economy
maintains a set rate of exchange between its currency and another currency or a basket of
currencies. Often the exchange rate is allowed to move within a narrow predetermined
(although not always announced) band. Pegs are maintained through a variety of
measures, including capital controls and intervention.
Real Effective Exchange Rate (REER) – A weighted average of bilateral exchange rates,
expressed in price-adjusted terms. Unlike the nominal effective exchange rate, it is further
adjusted for the effects of inflation in the countries concerned.
Trade Weighted Exchange Rate – see Nominal Effective Exchange Rate.
32 | https://www.scribd.com/document/391072143/Treasury-Fall-2018-FX-Report | CC-MAIN-2019-04 | refinedweb | 13,913 | 50.06 |
I have an assignment a C++ assignment and here is my code so far;
#include <iostream.h> #include <stdlib.h> #include <cstring> #include <cctype> class Student { private: char Name[80]; long SSN ; public: Student (char, long); void setSSN (int SSN); void setName (int Name); int getSSN (long); int getName (char); }; Student::Student (char Name, long SSN) { char Name [80] = "unassigned"; long SSN = 999999999; } int Student::getName() { return Name; } int Student::getSSN() { return SSN; } void Student::setName(int name) { int name = "John Doe" } void Student::setSSN(int ssn) { int ssn = 123456789 } void printName(Student *nameprint); void updateName(Student *nameprint); void printSSN(Student *ssnprint); void updateSSN(Student *ssnprint); int main() { Student myStudent; Student mySSN; printName(&myStudent); updateName(&myStudent); printName(&myStudent); printSSN(&mySSN); updateSSN(&mySSN); printSSN(&mySSN); return 0; } void printName(Student *dName) { cout << dName->getName( ) << endl; } void printSSN(Student *dSsn) { cout << dSsn->getSSN( ) << endl; } void updateName(Student *nameprint) { namePrint->setName(int name); } void updateSSN(Student *ssnprint) { namePrint->setSSN(int ssn); }
I need it to do this:
Create a class named Student. The class should consist of the following private member variables: social security number and name (last, first or first, last?). The social security number (SSN) should be a long integer. The name variable should be a character array of 80 characters. (This means use a C-style string only. You may not use a string/String class anywhere.)
Create the following class member functions: setSSN, getSSN, setName, getName. Each of the functions should be public.
The setSSN function should accept 1 argument and update the the social security number member variable. Do not allow the the social security number to be set to zero or less than zero. The getSSN should return the class SSN.
The setName member function should accept one string argument. Use the argument to update the name class member variable. Do not update the class variable for name if the argument has a length of 0. (This indicates the name in the argument is "empty".) The getName method should return the class value for name.
Create a default constructor. (This constructor will accept no arguments.) Use the default constructor to initialize the social security number to 999999999 and the name to "unassigned".
Make sure all your methods are defined in the implementation section of the class. Do not use any inline member functions.
Do not print from the Student class. Instead retrieve the data in the main() function and print from main.
Create a main function. In the main method create two Student objects. Use the appropriate get functions to print all the values of all the member variables for the first Student object. For the second object, use the set methods to change the student name to John Doe and the social security number to 123456789. Use the appropriate get functions to print all the values of all the member variables for the second Student object.
I am having MANY issues, what am I doing wrong?? | https://www.daniweb.com/programming/software-development/threads/274283/problems-with-my-program-any-help-will-be-appreciated | CC-MAIN-2016-50 | refinedweb | 490 | 64.91 |
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side by side
ncurses 5.7 - patch 20101128
[ncurses.git]
/
NEWS
diff --git
a/NEWS
b/NEWS
index 8614a009c98b02bb4602c17dd59ddff116a6e1c9..6a919665159cbdfa4de3e19d16a5d08ecda4ba9e 100644
(file)
--- a/
NEWS
+++ b/
NEWS
@@
-25,7
+25,7
@@
-- sale, use or other dealings in this Software without prior written --
-- authorization. --
-------------------------------------------------------------------------------
--- $Id: NEWS,v 1.1
504 2010/02/13 22:44:31
tom Exp $
+-- $Id: NEWS,v 1.1
615 2010/11/28 16:43:28
tom Exp $
-------------------------------------------------------------------------------
This is a log of changes that ncurses has gone through since Zeyd started
@@
-45,6
+45,338
@@
See the AUTHORS file for the corresponding full names.
Changes through 1.9.9e did not credit all contributions;
it is not possible to add this information.
@@
-221,7
+553,7
@@
it is not possible to add this information.
+ move leak-checking for comp_captab.c into _nc_leaks_tinfo() since
that module since 20090711 is in libtinfo.
+ add configure option --enable-term-driver, to allow compiling with
- terminal-driver. That is used in
mingw
port, and (being somewhat
+ terminal-driver. That is used in
MinGW
port, and (being somewhat
more complicated) is an experimental alternative to the conventional
termlib internals. Currently, it requires the sp-funcs feature to
be enabled.
@@
-638,7
+970,7
@@
it is not possible to add this information.
overlooked til now.
20081011
- +
update
html documentation.
+ +
regenerated
html documentation.
+ add -m and -s options to test/keynames.c and test/key_names.c to test
the meta() function with keyname() or key_name(), respectively.
+ correct return value of key_name() on error; it is null.
@@
-2765,7
+3097,7
@@
it is not possible to add this information.
(request by Mike Aubury).
+ add symbol to curses.h which can be used to suppress include of
stdbool.h, e.g.,
- #define NCURSES_ENABLE_STDBOOL_H 0
+ #define NCURSES_ENABLE_STDBOOL_H 0
#include <curses.h>
(discussion on XFree86 mailing list).
ncurses, with patches starting at ncurses-5.6; new users should use
RSS
Atom | https://ncurses.scripts.mit.edu/?p=ncurses.git;a=blobdiff;f=NEWS;h=6a919665159cbdfa4de3e19d16a5d08ecda4ba9e;hp=8614a009c98b02bb4602c17dd59ddff116a6e1c9;hb=82035cb9d3375b8c65b4a5a5d3bd89febdc7e201;hpb=06d92ef542e2ae2f48541e67a02acc50336e981c | CC-MAIN-2021-31 | refinedweb | 331 | 62.75 |
Introduction
About a month ago, I was using the MoTeC i2 Data Analysis software to look through some telemetry data that I had exported from a popular racing simulator game. Although MoTeC is feature rich and a great tool for motor racing professionals and enthusiasts, I had the idea to create a simplified, styled version using Silverlight. I had been looking for an interesting idea to test out my newfound Silverlight skills for a while, and this seemed like the perfect opportunity.
Before reading the rest of the article, you may like to view the sample application, located at the bottom of this post.
Using the Code
Architecture
The application as it is presented here is not the first version that I created. I had worked on an initial version before this which did not use the MVVM pattern. As a result of this, making changes were difficult, duplicate strings representing the same series name were littered throughout the application, the code behind was duplicated for each of the three chart components, and performance was far less than optimal. In my defense, the application I first envisioned was a single, simple chart with one series and no further information. But when I started to expand the application, all of these issues arose and started to get progressively worse.
So I decided to start again, switching to a cleaner, more manageable architecture that made use of data binding and limited code behind. The code is now structured using the MVVM architectural pattern . This should hopefully be clear by examining the solution and source code provided alongside the article.
Model
When creating the model, the aim was for it to be as reusable as possible. Originally I had dependencies on the Visiblox Charting Component (see the Charts section). However, these were removed, in favour of a model with simple lists of values. It would be the responsibility of the ViewModel to convert these values into the appropriate format before they were displayed by the charts in the view.
The model in the solution provided is in the
TelemetryData Project. This project reads and parses the .csv values exported from MoTeC.
TelemetryDataProvider implements
ITelemetryDataProvider and creates and populates a list of
TelemetrySeries in its constructor. One of the main goals when creating the
TelemetryDataProvider was for it to be as generic as possible. Users of the model can therefore obtain a list of
strings representing the names of all the series by reading the
SeriesList property. This means the
string representations of the series names do not need to be replicated anywhere else in the code. Users can also obtain a particular telemetry series by calling the
FindSeriesFromName method and passing a
string representation of the
TelemetrySeries.
A
TelemetrySeries represents a series of
TimestampedDataPoints along with the Name of the series and the index of the column in the csv file that the series data is stored in.
The next challenge was how to populate the
SeriesList in
TelemetryDataProvider. In the
ReadFile(StreamReader) method, the provider creates a
TelemetrySeriesDictionaryPopulator, passing its constructor the location of the .csv file and the
SeriesList. For every valid line in the .csv file, the
TelemetrySeriesDictionaryPopulator will call its
FillFromCSV method, which will add the relevant values to each
AllSeries entry, based on the entry's
IndexInCSV value.
One of my favourite things about the way
TelemetryDataProvider is implemented is how easy it is to add new Series data to the application. To add a
TelemetrySeries to the application, only one line of code is required:
_allSeries.Add(new TelemetrySeries("Series_Name", IndexInCSVFile));
This will add a series to the application, and no other references in the project need to be updated for the series to be visible. The
FillFromCSV method mentioned earlier will also need no modifications. I chose to display the 10 data sets which I saw to be most appropriate, but this is easily configurable through
TelemetryDataProvider. There are 115 columns to choose from in the exported MoTeC file.
View
The View presents the data provided by the View Model. Both the View and View Model are located in the
TelemetryPrototype project. There is very little code behind in the .xaml view files. The only code that is present is strictly necessary and could not be easily achieved through XAML.
TelemetryChannelCollectionView for example, rebuilds the
ChannelView grid depending on how many
ChannelViews are currently being displayed. Through reducing the code behind, I was able to ensure that the
View and the
ViewModel became almost independent of each other. This allows other Views to be attached to the same ViewModel in future, without any loss of functionality.
The views are attached to the view model through the use of .xaml bindings, which update automatically when the respective property in the ViewModel changes.The
TelemetryView,
TelemetryChannelCollectionView and
TelemetryChannelView have their Data Contexts set to their ViewModels upon initialisation, which are described in the section below.
ViewModel
I wanted all of the logic of the application to be contained in the ViewModel and not inside of the Model or the View. The ViewModel therefore abstracts from the View and provides a binding between the View and the Model. Any commands from the View are simply passed to the ViewModel via an
ICommand object, which will cause some property on the ViewModel to update. Through bindings, this will then update the view accordingly.
TelemetryViewModel provides the top level data context, and contains a
TelemetryChannelCollectionViewModel which stores and displays the
ChannelViewModels currently added to the application. It also holds properties for the custom controls in the bottom panel, which are updated in
ViewModelBase as well as Commands for playback speed, restart, full data, play/pause, import data and add chart.
Another of its main responsibilities is to update the charts during live playback of the data. The
UpdateChannelViewModels method is called by a dispatcher timer every 50ms.It calculates the time elapsed since the last update, and then calls
updateChart on the
ChannelViewModels in the
ChannelViewModel collection. The widgets are also updated based on the counter. If the chart is paused, the widgets are updated based on the selected index of the top chart (which should be synchronised with the other charts in the application).
The
TelemetryChannelViewModel contains the properties and values required to display a chart. It provides the data context for a
TelemetryChannelView and contains two data series to display on the chart from that view. It also contains behaviours and operations to modify, remove and add data series to the chart.
Charts
Custom Zoom Behaviour
To add the charts to the application, I used Visiblox Silverlight Charts. I chose to use Visiblox as I was looking for a high performance charting component. I knew I would be plotting a lot of data on the charts and the performance comparisons on Colin Eberhardt's blog here, as well as opinions on Stack Overflow led me to select Visiblox. I found the examples to be a great help when setting up the charts for the application.
Sticking to the MVVM architecture for the charts, the data for the charts comes from the Model, is converted by the ViewModel and displayed by the View, using the following method. Each chart is populated by its
TelemetryChannelViewModel, which obtains data for the two series from the
GetChannelData method in
TelemetryViewModel. This method retrieves the relevant
TelemetrySeries from the Data Provider in the Model, and calls
TelemetryDataToVisibloxDataSeries, which adds each point in the
TelemetrySeries to a
Visiblox DataSeries type. The
Visiblox LineSeries'
DataSeries in
TelemetryChannelView then has a binding to the
TelemetryChannelViewModel's
LivePrimaryChartDataSeries/
LiveSecondaryChartDataSeries property.
<visi:LineSeries DataSeries="{Binding Path=LivePrimaryChartDataSeries}" ...
To keep the data series on each of the charts in context, I decided it would be a good idea to restrict the zoom behaviours to the X-Axis. There is no way to restrict the standard Visiblox
ZoomBehaviour to the X-Axis, so I had to define a new one.
XAxisZoomBehaviour implements the Visiblox
BehaviourBase abstract Class. The
MouseLeftButtonDown method sets a zoom rectangle to the height of the chart, and when the
MouseMove method is called, the width of this rectangle is modified to the value of the mouse position minus the start position. The method also checks if the rectangle covers a large enough area on the chart to allow a zoom. By checking this, it stops the zoom area from becoming too small.If the mouse is released and the zoom area is large enough, the
ZoomTo method is called.
Storyboard sb = new Storyboard(); DoubleAnimation b = new DoubleAnimation() { From = Chart.XAxis.Zoom.Scale, To = zoom.Scale }; b.Duration = new Duration(new TimeSpan(0, 0, 0, 0, milliseconds)); sb.Children.Add(b); Storyboard.SetTarget(b, Chart.XAxis.Zoom); Storyboard.SetTargetProperty(b, new PropertyPath("(Scale)")); DoubleAnimation b2 = new DoubleAnimation() { From = Chart.XAxis.Zoom.Offset, To = zoom.Offset }; b2.Duration = new Duration(new TimeSpan(0, 0, 0, 0, milliseconds)); sb.Children.Add(b2); Storyboard.SetTarget(b2, Chart.XAxis.Zoom); Storyboard.SetTargetProperty(b2, new PropertyPath("(Offset)"));
This code from
ZoomTo creates two double animations, one for the Scale, and one for the Offset of the zoom. This is the code which actually modifies the offset and scale of the chart when the storyboard
sb begins.
Controls
When the charts were added to the application, I still felt like it was missing something. I had the idea to add widget-style custom controls below the chart to add more interest and interactivity. Each of the controls is defined in its own class in the
TelemetryPrototype.controls namespace within the controls folder. They all have at least one dependency property and subscribe to
onPropertyChanged events, which allows the controls to automatically update whenever one of their dependency properties is modified. The layout and elements of all the controls are defined in the Generic.xaml file.
ThrottleBrakeControl.cs
Dependency Properties:Throttle, Brake
The throttle Control is a three column grid, with a throttle indicator on the left, a brake indicator on the right and labels in the centre. The indicators are created by displaying a rectangle inside of a border. The rectangles are styled appropriately (green for throttle and red for brake) and their height is bound to their respective dependency property.
CarLocationControl.cs
Dependency Properties:Position
The car location control shows where the car currently is on the track.The track itself was created in Microsoft Expression Blend 4 using a path. The
Microsoft.Expression.Controls and
Microsoft.Expression.Drawing .dll files are therefore included in the references of this project. A
PathListBox then binds its
LayoutPath SourceElement to this path. The car itself is simply an ellipse inside of this
PathListBox. By binding the
Start property of the
LayoutPath to the
Position dependency property, the ellipse will move around the path.
Position must therefore be a percentage value. To calculate the percentage completion of a lap, it is necessary to have the start and end distance, which are calculated in the TelemetryDataProvider.cs when the data is first read into the application.
GForceControl.cs
Dependency Properties:Lateral, Long
There is slightly more code for the G-Force control and no bindings for the values on the chart, as these are set manually whenever a property changes in the
OnLateralPropertyChanged and
OnLongPropertyChanged methods. Within the
OnApplyTemplate() method of the control, a
DataPoint is created and added to a line series. This line series is then added to the chart.
The G-Force chart has also been retemplated to remove the border and to hide any axis values. The template is contained in App.xaml, with a target type of Chart. It has a key value of Gchart, which is referenced in the control's layout in the Generic.xaml by
"Template="{StaticResource Gchart}".
SpeedometerControl.cs
The speedometer control is a modified version of the gauge control developed by Colin Eberhardt as part of a blog post entitled "Developing a (very) Lookless Silverlight Radial Gauge Control". The only modifications from the original source code from the article are the styles, layout and namespace declarations. The style is defined at the bottom of the generic.xaml file in the Themes folder of the
SilverTrack project.
Util/Other Classes
Data Context Changed Handler
In order to register change events on the Data Context within the Telemetry Application, Jeremy Likeness'
DataContextChangedHelper class was used.
App.xaml
The styles, brushes, and custom templates for the charts are all defined in the App.xaml file.
Generic.xaml
The layout for the controls and the templates are defined in the Generic.xaml file.
Points of Interest
This was the first time I had used the MVVM architecture, and I will certainly use it again in the future. I had developed a prototype version of this application without MVVM. I had planned on building on this to create the final version, but found that it was much harder to modify and add additional functionality to. Mixing UI code with Logic code is bad practice, and it is something I will now be keen to avoid in the future.
It was also the first time I had used a charting component in Silverlight, other than the toolkit version. I decided on Visiblox after reading this article from Colin Eberhardt and others like it, as well as reading charting recommendations from members of Stack Overflow.
Exporting Data From MoTeC
Using the import data button in the top left of the application, it is possible to load your own MoTeC data into SilverTrack. If you do not wish to use the sample files provided, and have your own way to import telemetry data to MoTeC, exporting to the .csv format used by the application is relatively straightforward:
- Open a Log File, then select Export Data...
- Set current range to a single lap, and output format as CSV.
- Performance is optimal with sample rate of 20Hz.
- Include Time Stamp and Distance Data.
NOTE: The car location control will only operate correctly if you load data from the Calder Road Course. | https://blog.scottlogic.com/2012/06/07/creating-a-telemetry-application-using-silverlight-visiblox-and-custom-controls.html | CC-MAIN-2018-34 | refinedweb | 2,324 | 54.22 |
I hate writing client/server code. Why? Look at this example:
export interface User { name: string } export async function greet(user: User) { await doSomeStuff(user) return `Hellow ${user.name}` }
And this client code using it:
const jack: User = { name: 'Jack' } greet(jack).then(console.log)
If my
greet() function is executed in the client environment, then I just need to import it and I'm done. Everything works perfectly, I get proper type-checking, etc. But if it has to be executed on the server environment, then I would need to add this network layer boilerplate-ish to the server to make it work:
import express from 'express' import cors from 'cors' import { greet } from './my-func' const app = express() app.use(cors()) app.post('/greet', async (req, res) => { const user = JSON.parse(req.query.user) const response = await greet(user) res.status(200).send(response) }) app.listen(4000)
And this boilerplate-ish to the client:
export interface User { name: string } export async function greet(user: User) { const stringified = JSON.stringify(user) const encoded = encodeURIComponent(stringified) const response = await fetch( `{encoded}`, { method: 'POST' } ) return await response.text() }
The problem is not just that this is a lot of boilerplate, but also:
It is boilerplate that also introduces (and depends on) TONs of arbitrary decisions. The http method is one example (is it / was it / should it be POST / GET / PUT?), the URL is another one, as is the place where the parameters are put (the body, the query parameters, the URL itself, etc).
I've lost any meaningful type-checking now. I am maintaining two versions of
Userinterface and two definitions of
greet()function that I need to keep in sync manually.
Sharing Types
If we look at the main server code (where
greet() and
User are defined) and frontend boilerplate code, we can see that these two files have identical types. The body of
greet() differs between them, but all type declarations are exactly the same (TypeScript would generate the same
.d.ts file for both):
export interface User { name: string } export declare function greet(user: User): Promise<string>
What if we could share this type definition between server and client? This way, we would have a single source of truth for our types, while the client would get seamless type-checking.
How could we share type definitions? Well, people coding in TypeScript need to use lots of pure JavaScript libraries without loosing type checking, so TypeScript allows adding independent type definitions alongside JavaScript code. This means we can have different versions of our functions (e.g.
greet()) to actually share their type definitions, which is exactly what we need since our functions, though identical in type, need to behave differently on the server and on the client.
This would mean that we would need to write the frontend network layer code in JavaScript, then extract type definition files from backend code and set them alongside each other. It would resolve the type checking issue, but introduce the problem of manually maintaining a JavaScript code that needs to be in sync with those type definitions.
Auto-Generating Boilerplates
Well what if we could auto-generate the JavaScript code of the frontend boilerplate as well? If written in pure JavaScript, this boilerplate would look like this:
function greet(user) { const stringified = JSON.stringify(user) const encoded = encodeURIComponent(stringified) const response = await fetch( `{encoded}`, { method: 'POST' } ) return await response.text() } module.exports = { greet }
To write this code, we would need to know the following (and nothing more):
- The name of the function
greet()
- The URL of the corresponding endpoint
- The http method of the corresponding endpoint
- Where parameters should be injected (request body, header, url, query parameters, etc)
Note that the last 3 are the exact same problematic arbitrary choices we encountered in problem #1. Since the choices are (mostly) arbitrary, we could just decide on them based on the only non-arbitrary parameter here, i.e. the function name. For example, we could follow this convention:
👉 If the function name is "getX()": - the URL would be "/x" - the method would be GET - parameters would be in query params 👉 If the function name is "updateX()": - the URL would be "/x" - the method would be PUT - parameters would be in request body 👉 If the function name is "createX()": - the URL would be "/x" - the method would be POST - parameters would be in request body 👉 If the function name is "x()": - the URL would be "/x" - the method would be POST - parameters would be in request body
This means that knowing only the names of the functions and assuming they follow this convention, we could fully auto-generate the client-side boilerplate.
The backend boilerplate would also need to strictly follow this convention. Fortunately, that code can also be fully auto-generated knowing the names of the functions and following the same convention:
import express from 'express' import cors from 'cors' import { greet } from './my-func' const app = express() app.use(cors()) app.post( // --> from the convention '/greet', // --> from the convention async (req, res) => { const user = JSON.parse(req.body.user) // --> from the convention const response = await greet(user) // --> from function name res.status(200).send(response) } ) app.listen(4000)
Putting Everything Together
Let's recap a bit:
👉 Typical client/server code is problematic because:
- It has lots of boilerplate code with arbitrary decisions in it
- It takes type-checking away
👉 To fix that:
- We can share type definitions
- We can auto-generate client network layer boilerplate knowing function names and following some convention
- We can auto-generate server network layer boilerplate knowing function names and following some convention
All of these fixes rely on knowing the name of the server functions we want to use on the client-side. To fix that issue, lets add another rule: we will export all such functions from
index.ts on our server-side code, and our client/server code will be reduced to the following:
// server/index.ts export interface User { name: string } export async function greet(user: User) { await doStuff(user) return `Hellow ${user.name}` }
// client code import { greet } from '<auto-generated-code>' const jack: User = { name: 'Jack' } greet(jack).then(console.log)
Will this really work? Well I have actually built a CLI tool that does exactly what I've described here to find out. You can try it out for yourself:
👉 Install the CLI tool:
npm i -g tyfon
👉 Create a folder for server-side code:
mkdir test-server cd test-server npm init
👉 Add the server code:
// test-server/index.ts export interface User { name: string } export async function greet(user: User) { return `Hellow ${user.name}` }
👉 Run the server:
tyfon serve
🚀 You can already try out your server:
curl -d '{"0":{"name":"Jack"}}' -H "Content-Type: application/json" -X POST localhost:8000/greet
👉 Create a folder for the client-side code (in another terminal, keep the server running):
mkdir test-client cd test-client npm init npm i -g ts-node # --> if you don't have ts-node
👉 Autogenerate network boilerplate:
tyfon i localhost:8000
👉 Add the client code:
// test-client/index.ts import { User, greet } from '@api/test-server' const jack: User = { name: 'Jack' } greet(jack).then(console.log)
🚀 Try it out:
ts-node .
Observations
Although the TyFON CLI tool is pretty young and the concept of using type definitions as API specification is new (at least to me), I've been using it in real-life projects for some time now, and like everything else, there are pros and cons to this approach:
Pros
- Cleaner Code: I write simple functions on the server, and I call them on the client-side. The network layer (and all its boilerplate and hassle) completely vanishes.
- Strong Type Checking: When I make changes to server code that require changes in the client, my IDE will tell me, or when I want to call some server function, I don't need to go check a list of API URLs, the IDE suggests to me all the functions at my disposal.
- Single Source of Truth: All my data types are now defined in the server and seamlessly used in the client.
Cons / Oddities
- No Network Layer Access: The down-side of completely masking the network layer is that you won't have access to the network layer. This means right now I cannot put stuff in request headers or handle file uploads, though I've got some ideas of for tackling that issue
- No Middleware: I was used to Express middlewares that worked in tandem with Angular interceptors, to for example make authentication happen behind the scenes. Without any access to the network layer, all of that is gone as well, which means I have to explicitly pass auth tokens around now.
- New Security Concepts: Now I need to consider whether a server function is to be used internally by other functions or can it be safely used over network as well.
All in all, I am pretty happy with the early results of this approach. Of course as with anything new there are downsides and stuff that I would need to get used to, but the increase in development speed (and my confidence in the generated code) is so much that I will happily make that exchange for all possible future projects.
Discussion (2)
Hi, thanks for rising this point. I personally solved the issue by writing my server controller in typescript with tsoa annotations that generate a swagger. From it I can generate the ui stub. So, the server and client are sync.
Yes I've also seen TSOA and it seems pretty close in concept, though still it bears some overhead compared to TyFON (and of course in exchange it is more flexible and versatile). | https://practicaldev-herokuapp-com.global.ssl.fastly.net/loreanvictor/type-definitions-as-api-specification-36i | CC-MAIN-2021-17 | refinedweb | 1,623 | 56.59 |
I've tried to articulate this into google, but have failed to find anything useful describing it. Here's the code:
struct Segdesc gdt[] =
{
// 0x0 - unused (always faults -- for trapping NULL far pointers)
SEG_NULL,
// 0x8 - kernel code segment
[GD_KT >> 3] = SEG(STA_X | STA_R, 0x0, 0xffffffff, 0),
// 0x10 - kernel data segment
[GD_KD >> 3] = SEG(STA_W, 0x0, 0xffffffff, 0),
// 0x18 - user code segment
[GD_UT >> 3] = SEG(STA_X | STA_R, 0x0, 0xffffffff, 3),
// 0x20 - user data segment
[GD_UD >> 3] = SEG(STA_W, 0x0, 0xffffffff, 3),
// 0x28 - tss, initialized in trap_init_percpu()
[GD_TSS0 >> 3] = SEG_NULL
};
This obscure syntax is called a designated initializer and it lets you skip elements when creating an array aggregate.
Take a look at this program:
#include <stdio.h> int a[] = { 1, [2]=3, [5]=7 }; int main() { int i; for(i=0;i!=sizeof(a)/sizeof(int);i++) printf("a[%d] = %d\n", i, a[i]); return 0; }
It uses the same syntax to skip elements 1, 3, and 4 of the array
a.
This is what this program prints:
a[0] = 1 a[1] = 0 a[2] = 3 a[3] = 0 a[4] = 0 a[5] = 7
Your program does the same thing, but it initializes an array of structures, and calculating the indexes into its array aggregate using bit shifts of compile-time constants. You can find the values of these indexes in the comments (0x08, 0x10, 0x18, 0x20, and 0x28). | https://codedump.io/share/qfoQWdTsVlNj/1/weird-bracket-amp-macro-syntax-in-c | CC-MAIN-2016-50 | refinedweb | 231 | 58.96 |
2010-02-16 20:46:28 8 Comments
I have many "can't encode" and "can't decode" problems with Python when I run my applications from the console. But in the Eclipse PyDev IDE, the default character encoding is set to UTF-8, and I'm fine.
I searched around for setting the default encoding, and people say that Python deletes the
sys.setdefaultencoding function on startup, and we can not use it.
So what's the best solution for it?
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@twasbrillig 2018-04-12 21:38:57
This fixed the issue for me.
@Eric O Lebigot 2013-07-13 08:18:16
Here is a simpler method (hack) that gives you back the
setdefaultencoding()function that was deleted from
sys:
This is not a safe thing to do, though: this is obviously a hack, since
sys.setdefaultencoding()is purposely removed from
syswhen Python starts. Reenabling it and changing the default encoding can break code that relies on ASCII being the default (this code can be third-party, which would generally make fixing it impossible or dangerous).
@Sarah Messer 2015-08-07 16:03:34
Can you speak to the concerns raised in anonbadger.wordpress.com/2015/06/16/… ?(@ibotty raised them above)
@Eric O Lebigot 2015-08-08 00:22:26
@SarahMesser: These concerns are very relevant. I added a PS that mentions them. Thank you for the link!
@ibotty 2015-08-09 19:33:45
I downvoted, because that answer doesn't help for running existing applications (which is one way to interpret the question), is wrong when you are writing/maintaining an application and dangerous when writing a library. The right way is to set
LC_CTYPE(or in an application, check whether it is set right and abort with a meaningful error message).
@Eric O Lebigot 2015-08-10 00:16:39
@ibotty I do agree that this answer is a hack and that it is dangerous to use it. It does answer the question, though ("Changing default encoding of Python?"). Do you have a reference about the effect of the environment variable LC_CTYPE on the Python interpreter?
@ibotty 2015-08-10 11:46:16
well, it did not mention, it's a hack at first. other than that, dangerous answers that lack any mention that they are, are not helpful.
@ibotty 2015-08-10 11:49:52
@EOL, and the references re LC_CTYPE: docs.python.org/2/library/locale.html and docs.python.org/3/library/locale.html
@Eric O Lebigot 2015-08-10 17:55:41
@ibotty
LC_CTYPEis independent from the "default encoding of Python" that the question refers to (
sys.getdefaultencoding()returns
asciifor me, with
LC_CTYPE=en_US.UTF-8). So, what (different) problem that you have in mind does
LC_CTYPEsolve?
@ibotty 2015-08-11 08:05:38
@EOL you are right. It does effect the preferredencoding though (in python 2 and 3):
LC_CTYPE=C python -c 'import locale; print( locale.getpreferredencoding())'
@juan Isaza 2016-02-07 05:40:52
Worked on Python 2.7, but couldn't make it work on Python 3.4...
@Marlon Abeykoon 2016-06-07 09:31:30
@user2394901 The use of sys.setdefaultencoding() has always been discouraged!! And the encoding of py3k is hard-wired to "utf-8" and changing it raises an error.
@kiril 2016-09-16 13:11:13
I'm using ipython notebooks, and in my case, as soon as I execute the hack the print function no longer prints to stdout.
@Eric O Lebigot 2016-09-21 17:15:11
… and print still does not work when setting back the default encoding to 'ascii'… This smells like some magic done by the notebook… In any case, this solution is only a hack, and can thus break.
@Dalton Bentley 2017-06-05 23:41:02
This is a quick hack for anyone who is (1) On a Windows platform (2) running Python 2.7 and (3) annoyed because a nice piece of software (i.e., not written by you so not immediately a candidate for encode/decode printing maneuvers) won't display the "pretty unicode characters" in the IDLE environment (Pythonwin prints unicode fine), For example, the neat First Order Logic symbols that Stephan Boyer uses in the output from his pedagogic prover at First Order Logic Prover.
I didn't like the idea of forcing a sys reload and I couldn't get the system to cooperate with setting environment variables like PYTHONIOENCODING (tried direct Windows environment variable and also dropping that in a sitecustomize.py in site-packages as a one liner ='utf-8').
So, if you are willing to hack your way to success, go to your IDLE directory, typically: "C:\Python27\Lib\idlelib" Locate the file IOBinding.py. Make a copy of that file and store it somewhere else so you can revert to original behavior when you choose. Open the file in the idlelib with an editor (e.g., IDLE). Go to this code area:
In other words, comment out the original code line following the 'try' that was making the encoding variable equal to locale.getdefaultlocale (because that will give you cp1252 which you don't want) and instead brute force it to 'utf-8' (by adding the line 'encoding = 'utf-8' as shown).
I believe this only affects IDLE display to stdout and not the encoding used for file names etc. (that is obtained in the filesystemencoding prior). If you have a problem with any other code you run in IDLE later, just replace the IOBinding.py file with the original unmodified file.
@Att Righ 2017-05-25 20:50:07
Here is the approach I used to produce code that was compatible with both python2 and python3 and always produced utf8 output. I found this answer elsewhere, but I can't remember the source.
This approach works by replacing
sys.stdoutwith something that isn't quite file-like (but still only using things in the standard library). This may well cause problems for your underlying libraries, but in the simple case where you have good control over how sys.stdout out is used through your framework this can be a reasonable approach.
@kxr 2017-02-09 20:18:00
First:
reload(sys)and setting some random default encoding just regarding the need of an output terminal stream is bad practice.
reloadoften changes things in sys which have been put in place depending on the environment - e.g. sys.stdin/stdout streams, sys.excepthook, etc.
Solving the encode problem on stdout
The best solution I know for solving the encode problem of
print'ing unicode strings and beyond-ascii
str's (e.g. from literals) on sys.stdout is: to take care of a sys.stdout (file-like object) which is capable and optionally tolerant regarding the needs:
When
sys.stdout.encodingis
Nonefor some reason, or non-existing, or erroneously false or "less" than what the stdout terminal or stream really is capable of, then try to provide a correct
.encodingattribute. At last by replacing
sys.stdout & sys.stderrby a translating file-like object.
When the terminal / stream still cannot encode all occurring unicode chars, and when you don't want to break
print's just because of that, you can introduce an encode-with-replace behavior in the translating file-like object.
Here an example:
Using beyond-ascii plain string literals in Python 2 / 2 + 3 code
The only good reason to change the global default encoding (to UTF-8 only) I think is regarding an application source code decision - and not because of I/O stream encodings issues: For writing beyond-ascii string literals into code without being forced to always use
u'string'style unicode escaping. This can be done rather consistently (despite what anonbadger's article says) by taking care of a Python 2 or Python 2 + 3 source code basis which uses ascii or UTF-8 plain string literals consistently - as far as those strings potentially undergo silent unicode conversion and move between modules or potentially go to stdout. For that, prefer "
# encoding: utf-8" or ascii (no declaration). Change or drop libraries which still rely in a very dumb way fatally on ascii default encoding errors beyond chr #127 (which is rare today).
And do like this at application start (and/or via sitecustomize.py) in addition to the
SmartStdoutscheme above - without using
reload(sys):
This way string literals and most operations (except character iteration) work comfortable without thinking about unicode conversion as if there would be Python3 only. File I/O of course always need special care regarding encodings - as it is in Python3.
Note: plains strings then are implicitely converted from utf-8 to unicode in
SmartStdoutbefore being converted to the output stream enconding.
@kiril 2016-09-16 13:25:47
Regarding python2 (and python2 only), some of the former answers rely on using the following hack:
It is discouraged to use it (check this or this)
In my case, it come with a side-effect: I'm using ipython notebooks, and once I run the code the ´print´ function no longer works. I guess there would be solution to it, but still I think using the hack should not be the correct option.
After trying many options, the one that worked for me was using the same code in the
sitecustomize.py, where that piece of code is meant to be. After evaluating that module, the setdefaultencoding function is removed from sys.
So the solution is to append to file
/usr/lib/python2.7/sitecustomize.pythe code:
When I use virtualenvwrapper the file I edit is
~/.virtualenvs/venv-name/lib/python2.7/sitecustomize.py.
And when I use with python notebooks and conda, it is
~/anaconda2/lib/python2.7/sitecustomize.py
@Sebastian Duran 2016-12-05 06:57:13
Is you want to write spanish words (para escribir la ñ en python)
@ccpizza 2018-01-27 21:44:04
UTF-8 works just fine for Spanish and there is no reason to use iso-8859-15 anymore. Moreover, with UTF-8 you can have Spanish, Chinese, Japanese, emoji, etc all in a single file.
@Martin Massera 2019-02-16 16:50:47
The
codingdirective specifies the coding for the .py file you are in, for python interpreter and the IDE. This question is about encoding and decoding strings inside a python program.
@tripleee 2019-02-19 13:56:14
This is also misleading because many beginners will simply copy/paste this without understanding that they actually need to save the file with the same encoding as they have declared in the
coding:declaration. Anyway, Python 3 defaults to UTF-8 which is probably what you should be using everywhere anyway. utf8everywhere.org
@ibotty 2015-06-17 07:30:07
There is an insightful blog post about it.
See.
I paraphrase its content below.
In python 2 which was not as strongly typed regarding the encoding of strings you could perform operations on differently encoded strings, and succeed. E.g. the following would return
True.
That would hold for every (normal, unprefixed) string that was encoded in
sys.getdefaultencoding(), which defaulted to
ascii, but not others.
The default encoding was meant to be changed system-wide in
site.py, but not somewhere else. The hacks (also presented here) to set it in user modules were just that: hacks, not the solution.
Python 3 did changed the system encoding to default to utf-8 (when LC_CTYPE is unicode-aware), but the fundamental problem was solved with the requirement to explicitly encode "byte"strings whenever they are used with unicode strings.
@iman 2014-11-21 16:33:51
If you get this error when you try to pipe/redirect output of your script
UnicodeEncodeError: 'ascii' codec can't encode characters in position 0-5: ordinal not in range(128)
Just export PYTHONIOENCODING in console and then run your code.
export PYTHONIOENCODING=utf8
@Pryo 2015-02-09 10:47:50
This is the only solution that made any difference for me. - I'm on Debian 7, with broken locale settings. Thanks.
@ibotty 2015-06-17 09:40:04
Set
LC_CTYPEto something sensible instead. It makes all the other programs happy as well.
@Tino 2015-09-27 23:28:06
A bigger bug in Python3 is, that
PYTHONIOENCODING=utf8is not the default. This makes scripts break just because
LC_ALL=C
@Att Righ 2017-05-25 20:43:14
Set LC_CTYPE to something sensible insteadThis is a reasonable suggestion. This doesn't work so well when you are trying to distribute code that just works on another person's system.
@Arthur2e5 2018-03-13 19:05:22
Debian and Redhat OSes use a
C.utf8locale to provide more sensible C. glibc upstream is working on adding it, so perhaps we should not be blaming Python for respecting locale settings\…?
@bisherbas 2019-06-29 03:08:16
Thank you so much! Spent hours online and eventually came across with your response. Adding that line into
.bashrcof Cygwin addresses the encoding problem with Python.
@ChristopheD 2010-02-16 20:52:49
Starting with PyDev 3.4.1, the default encoding is not being changed anymore. See this ticket for details.
For earlier versions a solution is to make sure PyDev does not run with UTF-8 as the default encoding. Under Eclipse, run dialog settings ("run configurations", if I remember correctly); you can choose the default encoding on the common tab. Change it to US-ASCII if you want to have these errors 'early' (in other words: in your PyDev environment). Also see an original blog post for this workaround.
@Sean 2011-04-30 00:40:13
Thanks Chris. Especially considering Mark T's comment above, your answer seems to be the most appropriate to me. And for somebody who's not primarily an Eclipse/PyDev user, I never would have figured that out on my own.
@Tim Diggins 2012-02-22 11:58:11
I'd like to change this globally (rather than once per run configuration), but haven't figured out how - have asked a separate q: stackoverflow.com/questions/9394277/…
@lukmdo 2011-10-25 16:55:23
A) To control
sys.getdefaultencoding()output:
ascii
Then
and
utf-16-be
You could put your sitecustomize.py higher in your
PYTHONPATH.
Also you might like to try
reload(sys).setdefaultencodingby @EOL
B) To control
stdin.encodingand
stdout.encodingyou want to set
PYTHONIOENCODING:
ascii ascii
Then
utf-16-be utf-16-be
Finally: you can use A) or B) or both!
@lukmdo 2015-02-04 00:34:16
(python2 only) separate but interesting is extending above with
from __future__ import unicode_literalssee discussion | https://tutel.me/c/programming/questions/2276200/changing+default+encoding+of+python | CC-MAIN-2019-47 | refinedweb | 2,695 | 62.78 |
poem benn Wondering about the whole human condition recently, I decided to have a look at some early source code to see if it could be tightened up in any way, or even spot any glaring bugs. [Ovid] has had a look at [id://49419|Genesis] before (which I think may actually be part of the Vedas:: namespace), but I wanted to check out the main 'init()' routine. <p>A quick Perl-rewrite-hack of John 1.1 initially produced the code below. Note - all code is untested - I didn't dare run it until after peer review. $things?? }; } </code> <p. <p. <p>So... refactoring and removing the "I made this, honest!" copyright stuff gives us something like this... <code> #!/usr/bin/perl use strict; use warnings; use Earth::Things; my %things = map {$_=> {'name'=>$_[0]} } (Earth::Things::list_all()); $things{men}{life}=$things{darkness}{shine} = "light"; </code> ...which I'm sure you'll agree is a lot neater, and a better base for expansion. Any volunteers for a sourceforge project? <p>Ben. | http://www.perlmonks.org/index.pl?displaytype=xml;node_id=287907 | CC-MAIN-2015-40 | refinedweb | 173 | 73.17 |
To be honest, I'm not really a big React fan myself, but recently I started to rediscover the library. Using Vue and going even as far as to create my own UI library, I came to appreciate the ecosystem and "time-to-deploy" that developing with React gave me. So, despite my past negative bias, I started to use React pretty extensively, even to a point of enjoyment. And news that broke out a few days before this post, about the Release Candidate (RC) for React v17 pleasantly surprised me.
So, in this post, I'd like to give you a brief overview of what's coming with the new version, and - spoiler warning - why the supposed "lack of new features" is actually a good thing.
What's RC anyway?
For those rather unfamiliar with all the software release cycle concepts, here's a small summary.
Release Candidate (RC for short) is a stage above alpha and beta (which you might be more familiar with). Here, the software (React in this case) is still in development, but with great potential to become a stable product.
There can be multiple RCs, with the last one becoming the stable or "production" release. Right now React 17 is at the stage of the first RC.
The problem with new features
For a UI library that seems to be at the forefront of web development, constantly introducing new concepts and pushing the web forward, the lack of any new developer-facing features seems kind of weird for the major release that React v17 is. No next hooks, no stable concurrent mode, no nothing! Just some minor "upgrades" under the hood. Is this a joke?
Alright, maybe I'm a bit sarcastic here, but hopefully, you get the point. I agree with the React team, that there's no need for fancy new features right now, just because the number gets a bump.
It wasn't that long ago that we got stable hooks, or experimental concurrent mode and suspense. React definitely doesn't stop getting new features. However, with its growth in popularity and usage (especially among big corporations), it's not a surprise that lately stability and "upgradeability" have been gaining increasingly more attention.
How does such an approach fit into the broader React landscape? Take the most recent case of hooks for example. Even though the official blog post that announced their stable release clearly mentioned that adopting them isn't mandatory, many developers jumped onto the hype train, implementing hooks, which often resulted in mixed feelings about the new feature.
Don't get me wrong, it's often desired to use the latest and greatest the moment it drops, but it's always not good to rush things. Using a new feature without proper understanding usually leads to confusion and messy code, rather than the hyped improved readability, clarity, and performance.
That's why I'm all-in on what's React v17 is going for. With only a few fixes here and there, it makes future upgrades much easier and less painful. This way, developers can upgrade when they want and how they want, going as far as to even using multiple versions of React at the same time with ease, and adopting new features only when the developers are clearly ready for them. That's some really BIG focus on things that really matter.
The new stuff
With opening thoughts out of the way, let me briefly discuss the new "underlying features" of React v17. Keep in mind that the core React team did a really good job of describing them in the official blog post, so I won't be going too much into detail here.
Gradual upgrades
What I've already discussed - the goal of the first React v17 release is to make React more "upgradeable". The React team correctly called this "feature" gradual upgrades, as they're meant to ease out the upgrade process, by not requiring you to upgrade your entire codebase all at once.
This is only possible thanks to a number of internal tweaks that are included in this new version.
Event delegation
For easier usage/nesting of apps that use different versions of React, a few changes have been made. Arguably the biggest one is related to event delegation.
You might know that in DOM, there's an event delegation mechanism, which allows you to listen for events on the upper-level element, while still being able to detect which lower-level element was interacted with, due to event bubbling up the node tree.
React uses it to its own advantage for better performance on large trees and additional functionalities. However, it always attached its event listeners to the most top-level document node (through
document.addEventListener()), resulting in potential conflicts when multiple React versions were used at the same time.
React v17 fixes that by registering listeners on the node ReactDOM renders to (i.e. root element), effectively getting rid of any potentially unwanted conflicts.
Event pooling
Sticking to events for now a feature called "event pooling" was apparently removed from v17. It reused the event object between different events while setting all fields to
null in-between the process. It was meant to improve performance in the older browsers, but as it's no longer the case with the modern ones, and the feature itself was also causing some issues, it was simply removed.
Effect cleanup
Next up, for the hooks lovers - a few improvements have been made to
useEffect() for better timing of the cleanup function.
useEffect(() => { // Side-effect return () => { // Cleanup }; });
The function is now run asynchronously (just like the effect itself), while also executing in the same order as the effects.
Return undefined
React v17 also improves its handling of cases where
undefined is (most likely by accident) returned from the rendering function. This usually resulted in errors being thrown, but not so much for components wrapped in
memo() or
forwardRef().
const Button = () => { // Error <button />; }; const Button = forwardRef(() => { // Nothing <button />; }); const Button = memo(() => { // Nothing <button />; });
v17 standardizes the behavior by throwing errors in all of the above cases. Still, with modern coding tools and the advent of arrow functions, it's rather hard not to notice such error, but there's nothing wrong with having some additional protection.
Component stacks
Speaking of errors, the new version, also brings some improvements to them. Mainly the new mechanism for generating component stacks (organically introduced in v16) that results in better debugging experience, no matter the production or development environment.
Private exports
Lastly, some private exports containing the React internals have been removed. This shouldn't matter much to you unless you're using React Native for Web.
Test drive
So, these are the new features. Of course, there are some smaller performance improvements and other kinds of tweaks here and there, but that's pretty much it for the "breaking" changes.
If you want to see how much/little has changed, feel free to install the latest RC (not in a production of course) and take it for the test drive with the following command:
npm install react@next react-dom@next
The future is feature-packed
With all that said, for those of you striving for new features - rest assured - they'll come. Just like hooks which dropped in v16.8, new features aren't bound to a version number. Experimental features will eventually become stable, and new features will arrive as well. Just remember - it's good to be up-to-date with the latest and greatest, but it's not worth it to rush things. Keep your own pace, upgrade steadily, and confidently.
Speaking of up-to-date, if you really want to be up-to-date with all of my latest content, consider following me on Twitter, Facebook, or through my personal blog. Also, if you have any questions or thoughts about React v17, leave them in the comment section below. Thanks for reading and happy coding!
Discussion (1)
Good article. keep Going! | https://dev.to/areknawo/react-17-going-big-where-it-matters-68e | CC-MAIN-2021-21 | refinedweb | 1,338 | 60.55 |
A few weeks ago, I wrote about using React with Bridge.net. I described that I'd only written the bare minimum of bindings required to get my samples working - so, while I had a function for React.DOM.div -
[Name("div")] public extern static ReactElement Div( HTMLAttributes properties, params ReactElementOrText[] children );
The HTMLAttributes class I had written really was the bare minimum:
[Ignore] [ObjectLiteral] public class HTMLAttributes { public string className; }
It's time to revisit this and build up my bindings library!
An obvious resource to work from initially is the "DefinitelyTyped" bindings that allow you to use React from TypeScript. But I'd identified a pattern that I didn't like with them in my earlier post - the type system isn't being used to as full effect as it could be. For example, in the declaration of "input" elements. Let me explain (and please bear with me, I need to go through a few steps to get to the point)..
The TypeScript bindings describe a function for creating input elements:
React.DOM.input(props: HTMLAttributes, ...children: ReactNode[]): DOMElement
For any non-TypeScripters, this is a function that takes an argument named "props" that is of type HTMLAttributes, and then 0, 1, .. n arguments of type ReactNode that are wrapped up into an array (the same principle as "params" arguments in C#). It returns a DOMElement instance.
HTMLAttributes has 115 of its own properties (such as "className", "disabled" and "itemScope" - to take three at random) and extends DOMAttributes, which has 34 more properties (such as "onChange" and "onDragStart").
The "onChange" property is a FormEventHandler, which is derived from EventHandler<FormEvent>, where EventHandler<E> is a delegate which has a single "event" argument of type "E" which returns no value. It's a callback, in other words.
This looks promising and is, on the whole, a good use of TypeScript's generics system.
However, I don't think it uses this system enough. The FormEvent (that the "onChange" property passes in the callback) is a specialisation of a SyntheticEvent type:
interface FormEvent extends SyntheticEvent { } interface SyntheticEvent { bubbles: boolean; cancelable: boolean; currentTarget: EventTarget; defaultPrevented: boolean; eventPhase: number; isTrusted: boolean; nativeEvent: Event; preventDefault(): void; stopPropagation(): void; target: EventTarget; timeStamp: Date; type: string; }
(The EventTarget, which is what the "target" property is an instance of, is a DOM concept and is not a type defined by the React bindings, it just means that it is one of the DOM elements that are able to raise events).
The problem I have is that if we write code such as
React.DOM.input({ value: "hi" onChange: e => { alert(e.target.value); } })
Then we'll get a TypeScript compile error because "e.target" is only known to be of type EventTarget, it is not known to be an input element and so it is not known to have a "value" property. But we're specifying this "onChange" property while declaring an input element.. the type system should know that the "e.target" reference will be an input!
In fact, in TypeScript, we actually have to skirt around the type system to make it work:
// "<any>" means cast the "e.target" reference to the magic type "any", which // is like "dynamic" in C# - you can specify any property or method and the // compiler will assume you know what you're doing and allow it (resulting // in a runtime exception if you get it wrong) React.DOM.input({ value: "hi" onChange: e => { alert((<any>e.target).value); } })
In my React bindings for Bridge I improved this by defining an InputAttributes type:
[Ignore] [ObjectLiteral] public class InputAttributes : HTMLAttributes { public Action<FormEvent<InputEventTarget>> onChange; public string value; }
And having a generic FormEvent<T> which inherits from FormEvent -
[Ignore] public class FormEvent<T> : FormEvent where T : EventTarget { public new T target; }
This means that the "target" property can be typed more specifically. And so, when you're writing this sort of code in C# with Bridge.net, you can write things like:
// No nasty casts required! The type system knows that "e.target" is an // "InputEventTarget" and therefore knows that it has a "value" property // that is a string. DOM.Input(new InputAttributes { value = "hi", onChange = e => Global.Alert(e.target.value) })
This is great stuff! And I'm not changing how React works in any way, I'm just changing how we interpret the data that React is communicating; the event reference in the input's "onChange" callback has always had a "target" which had a "value" property, it's just that the TypeScript bindings don't tell us this through the type system.
So that's all good.. but it did require me to write more code for the bindings. The InputEventTarget class, for example, is one I had to define:
[Ignore] public class InputEventTarget : EventTarget { public string value; }
And I've already mentioned having to define the FormEvent<T> and InputAttributes classes..
What I'm saying is that these improvements do not come for free, they required some analysis and some further effort putting into the bindings (which is not to take anything away from DefinitelyTyped, by the way - I'm a big fan of the work in that repository and I'm very glad that it's available, both for TypeScript / React work I've done in the past and to use as a starting point for Bridge bindings).
Seeing how these more focussed / specific classes can improve things, I come to my second problem with the TypeScript bindings..
The place that I wanted to start in extending my (very minimal) bindings was in fleshing out the HTMLAttributes class. Considering that it had only a single property ("className") so far, and that it would be used by so many element types, that seemed like a reasonable plan. But looking at the TypeScript binding, I felt like I was drowning in properties.. I realised that I wasn't familiar with everything that appeared in html5, but I was astonished by how many options there were - and convinced that they couldn't all be applicable to all elements types. So I picked one at random, of those that stood out as being completely unfamiliar to me: "download".
w3schools has this to say about the HTML <a> download Attribute:
The download attribute is new for the <a> tag in HTML5.
and.).
So it appears that this attribute is only applicable to anchor tags. Therefore, it would make more sense to not have a "React.DOM.a" function such as:
[Name("a")] public extern static ReactElement A( HTMLAttributes properties, params ReactElementOrText[] children );
and, like the "input" function, to be more specific and create a new "attributes" type. So the function would be better as:
[Name("a")] public extern static ReactElement A( AnchorAttributes properties, params ReactElementOrText[] children );
and the new type would be something like:
[Ignore] [ObjectLiteral] public class AnchorAttributes : HTMLAttributes { public string download; }
This would allow the "download" property to be pulled out of HTMLAttributes (so that it couldn't be a applied to a "div", for example, where it has no meaning).
So one down! Many, many more to go..
Some properties are applicable to multiple element types, but these elements may not have anything else in common. As such, I think it would be more sensible to duplicate some properties in multiple attributes classes, rather than trying to come up with a complicated inheritance tree that tries to avoid any repeating of properties, at the cost of the complexities that inheritance can bring. For example, "href" is a valid attribute for both "a" and "link" tags, but these elements do not otherwise have much in common - so it might be better to have completely distinct classes
[Ignore] [ObjectLiteral] public class AnchorAttributes : HTMLAttributes { public string href; public string download; // .. and other attributes specified to anchor tags } [Ignore] [ObjectLiteral] public class LinkAttributes : HTMLAttributes { public string href; // .. and other attributes specified to link tags }
than to try to create a base class
[Ignore] [ObjectLiteral] public abstract class HasHrefAttribute : HTMLAttributes { public string href; }
which AnchorAttributes and LinkAttributes could be derived from. While it might appear initially to make sense, I imagine that it will all come unstuck quite quickly and you'll end up finding yourself wanting to inherit from multiple base classes and all sorts of things that C# doesn't like. I think this is a KISS over DRY scenario (I'd rather repeat "public string href;" in a few distinct places than try to tie the classes together in some convoluted manner).
So, with more thought and planning, I think a reduced HTMLAttributes class could be written and a range of attribute classes produced that make the type system work for us. I should probably admit that I haven't actually done any of that further thought or planning yet! I feel like I've spent this month coming up with grandiose schemes and then writing about doing them rather than actually getting them done! :D
Anyway, enough about my shortcomings, there's another issue I found while looking into this "download" attribute. Thankfully, it's a minor problem that can easily be solved with the way that bindings may be written for Bridge..
There was an issue on React's GitHub repo: "Improve handling of download attribute" which says the following:
Currently, the "download" attribute is handled as a normal attribute. It would be nice if it could be treated as a boolean value attribute when its value is a boolean. ... For example,
a({href: 'thing', download: true}, 'clickme'); // => <a href="thing" download>clickme</a>
a({href: 'thing', download: 'File.pdf'}, 'clickme'); // => <a href="thing" download="File.pdf">
This indicates that
[Ignore] [ObjectLiteral] public class AnchorAttributes : HTMLAttributes { public string href; public string download; // .. and other attributes specified to anchor tags }
is not good enough and that "download" needs to be allowed to be a string or a boolean.
This can be worked around by introducing a new class
[Ignore] public sealed class StringOrBoolean { private StringOrBoolean() { } public static implicit operator StringOrBoolean(bool value) => new StringOrBoolean(); public static implicit operator StringOrBoolean(string value) => new StringOrBoolean(); }
This looks a bit strange at first glance. But it is only be used to describe a way to pass information in a binding, that's why it's got the "Ignore" attribute on it - that means that this class will not be translated into any JavaScript by Bridge, it exists solely to tell the type system how one thing talks to another (my React with Bridge.net post talked a little bit about this attribute, and others similar to it, that are used in creating Bridge bindings - so if you want to know more, that's a good place to start).
This explains why the "value" argument used in either of the implicit operators is thrown away - it's because it's never used by the binding code! It is only so that we can use this type in the attribute class:
[Ignore] [ObjectLiteral] public class AnchorAttributes : HTMLAttributes { public string href; public StringOrBoolean download; // .. and other attributes specified to anchor tags }
And this allows to then write code like
DOM.a(new AnchorAttributes { href: "/instructions.pdf", download: "My Site's Instructions.pdf" })
or
DOM.a(new AnchorAttributes { href: "/instructions.pdf", download: true })
We only require this class to exist so that we can tell the type system that React is cool with us giving a string value for "download" or a boolean value.
The "ObjectLiteral" attribute on these classes means that the code
DOM.a(new AnchorAttributes { href: "/instructions.pdf", download: true })
is not even translated into an instantiation of a class called "AnchorAttributes", it is instead translated into a simple object literal -
// It is NOT translated into this React.DOM.a( Bridge.merge( new Bridge.React.AnchorAttributes(), { name: "/instructions.pdf", download: true } ) ) // It IS just translated into this React.DOM.a({ name: "/instructions.pdf", download: true })
Again, this illustrates why the "value" argument was thrown away in the StringOrBoolean implicit operator calls - because those calls do not exist in the translated JavaScript.
Another thing that I like about the "ObjectLiteral" attribute that I've used on these {Whatever}Attributes classes is that the translated code only includes the properties that have been explicitly set.
This means that, unlike in the TypeScript definitions, we don't have to declare all value types as nullable. If, for example, we have an attributes class for table cells - like:
[Ignore] [ObjectLiteral] public class TableCellAttributes : HTMLAttributes { public int colSpan; public int rowSpan; }
and we have C# code like this:
DOM.td(new TableCellAttributes { colSpan = 2 }, "Hello!")
Then the resulting JavaScript is simply:
React.DOM.td({ colSpan = 2 }, "Hello!")
Note that the unspecified "rowSpan" property does not appear in the JavaScript.
If we want it to appear, then we can specify a value in the C# code -
DOM.td(new TableCellAttributes { colSpan = 2, rowSpan = 1 }, "Hello!")
That will be translated as you would expect:
React.DOM.td({ colSpan = 2, rowSpan = 1 }, "Hello!")
This has two benefits, actually, because not only do we not have to mark all of the properties as nullable (while that wouldn't be the end of the world, it's nicer - I think - to have the attribute classes have properties that match the html values as closely as possible and using simple value types does so) but it also keeps the generated JavaScript succint. Imagine the alternative, where every property was included in the JavaScript.. every time a div element was declared it would have 150 properties listed along with it. The JavaScript code would get huge, very quickly!*
* (Ok, ok, it shouldn't be 150 properties for every div since half the point of this post is that it will be much better to create attribute classes that are as specific as possible - but there would still be a lot of properties that appear in element initialisations in the JavaScript which were not present in the C# code, it's much better only having the explicitly-specified values wind up in the translated output).
I was part way through writing about how pleased I was that unspecified properties in an [ObjectLiteral]-decorated class do not appear in the generated JavaScript when I decided to upgrade to Bridge 1.8 (which was just released two days ago).. and things stopped doing what I wanted.
With version 1.8, it seems like if you have an [ObjectLiteral] class then all of the properties will be included in the JavaScript - with default values if you did not specify them explicitly. So the example above:
DOM.td(new TableCellAttributes { colSpan = 2 }, "Hello!")
would result in something like:
React.DOM.td({ colSpan = 2, rowSpan = 0, id = null, className = null, // .. every other HTMLAttribute value here with a default value }, "Hello!" )
Which is a real pity.
The good news is that it appears to be as easy as also including an [Ignore] attribute on the type - doing so re-enables the behaviour that only includes explicitly-specifed properties in the JavaScript. However, I have been unable to find authoritative information on how [ObjectLiteral] should behave and how it should behave with or without [Ignore]. I had a quick flick through the 1.8 release notes and couldn't see any mention of this being an explicit change from 1.7 to 1.8 (but, I will admit, I wasn't super thorough in that investigation).
I only came across the idea of combining [Ignore] with [ObjectLiteral] when I was looking through their source code on GitHub (open source software, ftw!) and found a few places where there are checks for one of those attributes or both of them in some places.
(I've updated the code samples in this post to illustrate what I mean - now anywhere that has [ObjectLiteral] also has [Ignore]).
I'm a little bit concerned that this may change again in the future or that I'm not using these options correctly, but I've raised a bug in their forums and they've been very good at responding to these in the past - ObjectLiteral classes generate values for all properties in 1.8 (changed from 1.7).
So.. how am I intending to progress this? Or am I going to just leave it as an interesting initial investigation, something that I've looked briefly into and then blogged about??
Well, no. Because I am actually planning to do some useful work on this! :) I'm a big fan of both React and Bridge and hope to be doing work with both of them, so moving this along is going to be a necessity as much as a nice idea to play around with. It's just a case of how to proceed - as the I-have-never-heard-of-this-new-download-attribute story goes to show, I'm not intimately familiar with every single tag and every single attribute, particular in regards to some of the less well-known html5 combinations.
Having done some research while writing this post, I think the best resource that I've found has been MDN (the Mozilla Developer Network). It seems like you can look up any tag - eg.
And then find details of every attribute that it has, along with compatibility information. For example, the "td" table cell documentation..
.. mentions "colSpan" and "rowSpan", with no particular mentions of compatibility (these have existed from day one, surely, and I don't think they're going to disappear any time soon) but also mentions attributes such as "align" and "valign" and highlights them as deprecated in html 4.01 and obsolete in html 5.
I'm strongly considering scraping these MDN pages and trying to parse out the attribute names and compatibility information (probably only supporting html5, since what's the point in supporting anything older when Bridge and React are new and and so I will be using them for writing new code and taking advantage of current standards). It doesn't provide type information (like "colSpan" is numeric or "download" may be a string or a boolean), but the DefinitelyTyped definitions will go some way in helping out with that. And MDN says that its wiki documents are available under the creative commons license, so I believe that this would acceptable use of the data, so long as they are given the appropriate credit in the bindings code that I will eventually generate (which only seems fair!).
So I think that that is what will come next - trying to glean all of the information I need about the attributes specific to particular tags and then using this to produce bindings that take as much advantage of the C# type system as possible!
Unless I'm missing something and someone else can think of a better way? Anyone??
Update (8th October 2015): I've had some suggestions from a member of the Bridge.net Team on how to reuse some of their work on html5 element definitions to make this a lot easier - so hopefully I'll have an update before too long based upon this. Before I can do so, the Bridge Team are looking into some improvements, such as allowing the "CurrentTarget" property of elements to be more strongly-typed (see), but hopefully we'll all have an update before too long!
Posted at 23:07
Earlier this week, I was talking about parsing TypeScript definitions in an inspired-by-function-programming manner. Like this:
public static Optional<MatchResult<PropertyDetails>> Property ); }
"Identifier", "Whitespace" and "TypeScriptType" are functions that match the following delegate:
public delegate Optional<MatchResult<T>> Parser<T>( IReadStringContent reader );
.. while "Match" is a function that returns a Parser<char>.
The MatchResult class looks like this: { /// <summary> /// Convenience method to utilise C# type inherence /// </summary> public static MatchResult<T> New<T>(T value, IReadStringContent reader) { if (value == null) throw new ArgumentNullException(nameof(value)); if (reader == null) throw new ArgumentNullException(nameof(reader)); return new MatchResult<T>(value, reader); } }
.. and Optional is basically a way to identify a type as being maybe-null (the convention then being that any non-Optional type should never be null).
Feel free to fresh your memory at Parsing TypeScript definitions!
One thing that I thought was very un-functional-like (a very precise term! :) was the way that the "name" and "type" values were updated via callbacks from the "Then" methods. This mechanism felt wrong for two reasons; the repeat assignment to the references (setting them to null and then setting them again to something else) and the fact that the assignments were effectively done as side effects of the work of the "Then" function.
So I thought I'd have a look into some alternatives and see if I could whip up something better.
The current approach chains together functions that take and return Optional<IReadStringContent> instances. If content is encountered that does not match the specified Parser then a "Missing" value will be returned from the "Then" call. If a "Then" call receives a "Missing" value then it passes that straight out. So, any time that a match is missed, all subsequent calls pass the "Missing" value straight throught.
This is why the side effect callbacks are required to pass out the values, because each "Then" call only returns the next position for the reader (or "Missing" if content did not meet requirements).
To change this, the "Then" function will need to return additional information. Conveniently, there is already a structure to do this - the MatchResult<T>. As long as we had one result type that we wanted to thread through the "Then" calls then we could write an alternate version of "Then" -
public static Optional<MatchResult<TResult>> Then<TResult, TValue>( this Optional<MatchResult<TResult>> resultSoFar, Parser<TValue> parser, Func<TResult, TValue, TResult> updater) { if (!resultSoFar.IsDefined) return null; var result = parser(resultSoFar.Value.Reader); if (!result.IsDefined) return null; return MatchResult.New( updater(resultSoFar.Value.Result, result.Value.Result), result.Value.Reader ); }
This takes an Optional<MatchResult<T>> and tries to match content in the reader inside that MatchResult using a Parser (just like before) - if it successfully matches the content then it uses an "updater" which takes the previous values from the MatchResult and the matched value from the reader, and returns a new result that combines the two. It then returns a MatchResult that combines this new value with the reader in a position after the matched content. (Assuming the content met the Parser requirements.. otherwise it would return null).
This all sounds very abstract, so let's make it concrete. Continuing with the parsing-a-TypeScript-property (such as "name: string;") example, let's declare an interim type -
public sealed class PartialPropertyDetails { public PartialPropertyDetails( Optional<IdentifierDetails> name, Optional<ITypeDetails> type) { Name = name; Type = type; } public Optional<IdentifierDetails> Name { get; } public Optional<ITypeDetails> Type { get; } }
This has Optional values because we are going to start with them being null (since we don't have any real values until we've done the parsing). This is the reason that I've introduced this interm type, rather than using the final PropertyDetails type - that type is very similar but it has non-Optional properties because it doesn't make sense for a correctly-parsed TypeScript property to be absent either a name or a type.
Now, the parsing method could be rewritten into this:
public static Optional<MatchResult<PropertyDetails>> Property(IReadStringContent reader) { var result = Optional.For(MatchResult.New( new PartialPropertyDetails(null, null), reader )) .Then(Identifier, (value, name) => new PartialPropertyDetails(name, value.Type)) .ThenOptionally(Whitespace) .Then(Match(':')) .ThenOptionally(Whitespace) .Then(TypeScriptType, (value, type) => new PartialPropertyDetails(value.Name, type)) .ThenOptionally(Whitespace) .Then(Match(';')); if (!result.IsDefined) return null; return MatchResult.New( new PropertyDetails(result.Value.Result.Name, result.Value.Result.Type), result.Value.Reader ); }
Ta-da! No reassignments or reliance upon side effects!
And we could make this a bit cleaner by tweaking PartialPropertyDetails -
public sealed class PartialPropertyDetails { public static PartialPropertyDetails Empty { get; } = new PartialPropertyDetails(null, null); private PartialPropertyDetails( Optional<IdentifierDetails> name, Optional<ITypeDetails> type) { Name = name; Type = type; } public Optional<IdentifierDetails> Name { get; } public Optional<ITypeDetails> Type { get; } public PartialPropertyDetails WithName(IdentifierDetails value) => new PartialPropertyDetails(value, Type); public PartialPropertyDetails WithType(ITypeDetails value) => new PartialPropertyDetails(Name, value); }
and then changing the parsing code into this:
public static Optional<MatchResult<PropertyDetails>> Property(IReadStringContent reader) { var result = Optional.For(MatchResult.New( PartialPropertyDetails.Empty, reader )) .Then(Identifier, (value, name) => value.WithName(name)) .ThenOptionally(Whitespace) .Then(Match(':')) .ThenOptionally(Whitespace) .Then(TypeScriptType, (value, type) => value.WithType(name)) .ThenOptionally(Whitespace) .Then(Match(';')); if (!result.IsDefined) return null; return MatchResult.New( new PropertyDetails(result.Value.Result.Name, result.Value.Result.Type), result.Value.Reader ); }
This makes the parsing code look nicer, at the cost of having to write more boilerplate code for the interim type.
What if we could use anonymous types and some sort of magic for performing the copy-and-update actions..
The problem with the PartialPropertyDetails is not only that it's quite a lot of code to write out (and that was only for two properties, it will quickly get bigger for more complicated structures) but also the fact that it's only useful in the context of the "Property" function. So this non-neligible chunk of code is not reusable and it clutters up the scope of whatever class or namespace has to contain it.
Anonymous types sound ideal, because they would just let us start writing objects to populate - eg.
var result = Optional.For(MatchResult.New( new { Name = (IdentifierDetails)null, Type = (ITypeDetails)null, }, reader )) .Then(Identifier, (value, name) => new { Name = name, Type = value.Type }) .ThenOptionally(Whitespace) .Then(Match(':')) .ThenOptionally(Whitespace) .Then(TypeScriptType, (value, type) => new { Name = value.Name, Type = Type }) .ThenOptionally(Whitespace) .Then(Match(';'));
They're immutable types (so nothing is edited in-place, which is just as bad as editing via side effects) and, despite looking like they're being defined dynamically, the C# compiler defines real classes for them behind the scenes, so the "Name" property will always be of type IdentifierDetails and "Type" will always be an ITypeDetails.
The compiler creates new classes for every distinct combination of properties (considering both property name and property type). This means that if you declare two anonymous objects that have the same properties then they will be represented by the same class. This is what allows the above code to declare "updater" implementations such as
(value, name) => new { Name = name, Type = value.Type }
The "value" in the lambda will be an instance of an anonymous type and the returned value will be an instance of that same anonymous class because it specifies the exact same property names and types. This is key, because the "updater" is a delegate with the signature
Func<TResult, TValue, TResult> updater
(and so the returned value must be of the same type as the first value that it was passed).
This is not actually a bad solution, I don't think. There was no need to create a PartialPropertyDetails class and we have full type safety through those anonymous types. The only (admittedly minor) thing is that if the data becomes more complex then there will be more and more properties and so every instantiation of the anonymous types will get longer and longer. It's a pity that there's no way to create "With{Whatever}" functions for the anonymous types.
Before I go any further, there's another extension method I want to introduce. I just think that the way that these parser chains are initiated feels a bit clumsy -
var result = Optional.For(MatchResult.New( new { Name = (IdentifierDetails)null, Type = (ITypeDetails)null, }, reader )) .Then(Identifier, (value, name) => new { Name = name, Type = value.Type }) // .. the rest of the parsing code continues here..
This could be neatened right up with an extension method such as this:
public static Optional<MatchResult<T>> StartMatching<T>( this IReadStringContent reader, T value) { return MatchResult.New(value, reader); }
This uses C#'s type inference to ensure that you don't have to declare the type of T (which is handy if we're using an anonymous type because we have no idea what its type name might be!) and it relies on the fact that the Optional struct has an implicit operator that allows a value T to be returned as an Optional<T>; it will wrap the value up automatically. (For more details on the Optional type, read what I wrote last time).
Now, the parsing code that we have look like this:
var resultWithAnonymousType = reader .StartMatching(new { Name = (IdentifierDetails)null, Type = (ITypeDetails)null }) .Then(Identifier, (value, name) => new { Name = name, Type = value.Type }) .ThenOptionally(Whitespace) .Then(Match(':')) .ThenOptionally(Whitespace) .Then(TypeScriptType, (value, type) => new { Name = value.Name, Type = Type }) .ThenOptionally(Whitespace) .Then(Match(';'));
Only a minor improvement but another step towards making the code match the intent (which was one of the themes in my last post).
Let's try turning the volume up to "silly" for a bit. (Fair warning: "clever" here refers more to "clever for the sake of it" than "intelligent).
A convenient property of the anonymous type classes is that they each have a constructor whose arguments directly match the properties on it - this is an artifact of the way that they're translated into regular classes by the compiler. You don't see this in code anywhere since the names of these mysterious classes is kept secret and you can't directly call a constructor without knowing the name of the class to call. But they are there, nonetheless. And there is one way to call them.. REFLECTION!
We could use reflection to create something like the "With{Whatever}" methods - that way, we could go back to only having to specify a single property-to-update in each "Then" call. The most obvious way that this could be achieved would be by specifying the name of the property-to-update as a string. But this is particularly dirty and prone to breaking if any refactoring is done (such as a change to a property name in the anonymous type). There is one way to mitigate this, though.. MORE REFLECTION!
Let me code-first, explain-later:
public static Optional<MatchResult<TResult>> Then<TResult, TValue>( this Optional<MatchResult<TResult>> resultSoFar, Parser<TValue> parser, Expression<Func<TResult, TValue>> propertyRetriever) { if (!resultSoFar.IsDefined) return null; var result = parser(resultSoFar.Value.Reader); if (!result.IsDefined) return null; var memberAccessExpression = propertyRetriever.Body as MemberExpression; if (memberAccessExpression == null) { throw new ArgumentException( "must be a MemberAccess", nameof(propertyRetriever) ); } var property = memberAccessExpression.Member as PropertyInfo; if ((property == null) || !property.CanRead || property.GetIndexParameters().Any()) { throw new ArgumentException( "must be a MemberAccess that targets a readable, non-indexed property", nameof(propertyRetriever) ); } foreach (var constructor in typeof(TResult).GetConstructors()) { var valuesForConstructor = new List<object>(); var encounteredProblemWithConstructor = false; foreach (var argument in constructor.GetParameters()) { if (argument.Name == property.Name) { if (!argument.ParameterType.IsAssignableFrom(property.PropertyType)) { encounteredProblemWithConstructor = false; break; } valuesForConstructor.Add(result.Value.Result); continue; } var propertyForConstructorArgument = typeof(TResult) .GetProperties() .FirstOrDefault(p => (p.Name == argument.Name) && p.CanRead && !property.GetIndexParameters().Any() ); if (propertyForConstructorArgument == null) { encounteredProblemWithConstructor = false; break; } var propertyGetter = propertyForConstructorArgument.GetGetMethod(); valuesForConstructor.Add( propertyGetter.Invoke( propertyGetter.IsStatic ? default(TResult) : resultSoFar.Value.Result, new object[0] ) ); } if (encounteredProblemWithConstructor) continue; return MatchResult.New( (TResult)constructor.Invoke(valuesForConstructor.ToArray()), result.Value.Reader ); } throw new ArgumentException( $"Unable to locate a constructor that can be used to update {property.Name}" ); }
This allows the parsing code to be rewritten (again!) into:
var result = reader .StartMatching(new { Name = (IdentifierDetails)null, Type = (ITypeDetails)null }) .Then(Identifier, x => x.Name) .ThenOptionally(Whitespace) .Then(Match(':')) .ThenOptionally(Whitespace) .Then(TypeScriptType, x => x.Type) .ThenOptionally(Whitespace) .Then(Match(';'));
Well now. Isn't that easy on the eye! Ok.. maybe beauty is in the eye of the beholder, so let me hedge my bets and say: Well now. Isn't that succint!
Those lambdas ("x => x.Name" and "x => x.Type") satisfy the form:
Expression<Func<TResult, TValue>>
This means that they are expressions which must take a TResult and return a TValue. So in the call
.Then(Identifier, x => x.Name)
.. the Expression describes how to take the anonymous type that we're threading through the "Then" calls and extract an IdentifierDetails instance from it (the type of this is dictated by the TValue type parameter on the "Then" method, which is inferred from the "Identifier" call - which returns an Optional<IdentifierDetails>).
This is the difference between an Expression and a Func - the Func is executable and tells us how to do something (such as "take the 'Name' property from the 'x' reference") while the Expression tells us how the Func is constructed.
This information allows the new version of "Then" to not only retrieve the specified property but also to be aware of the name of that property. And this is what allows the code to say "I've got a new value for one property now, I'm going to try to find a constructor that I can call which has an argument matching this property name (so I can satisfy that argument with this new value) and which has other arguments that can all be satisfied by other properties on the type".
Anonymous types boil down to simple classes, a little bit like this:
private sealed CRAZY_AUTO_GEN_NAME<T1, T2> { public CRAZY_AUTO_GEN_NAME(T1 Name, T2 Type) { this.Name = Name; this.Type = Type; } public T1 Name { get; } public T2 Type { get; } }
Note: I said earlier that the compiler generates distinct classes for anonymous types that have unique combinations of property names and types. That's a bit of a lie, it only has to vary them based upon the property names since it can use generic type parameters for the types of those properties. I confirmed this by using ildasm on my binaries, which also showed that the name of the auto-generated class was <>f_AnonymousType1.. it's not really called "CRAZY_AUTO_GEN_NAME" :)
So we can take the Expression "x => x.Name" and extract the fact the the "Name" property is being targeted. This allows us to match the constructor that takes a "Name" argument and a "Type" argument and to call that constructor - passing the new value into the "Name" argument and passing the existing "Type" property value into the "Type" argument.
This has the benefit that everything would still work if one of the properties was renamed in a refactor (since if the "Name" property was renamed to "SomethingElse" then Visual Studio would update the lambda "x => x.Name" to "x => x.SomethingElse", just as it would for any other reference to that "Name" property).
The major downside is that the "Then" function requires that the Expression relate to a simple property retrieval, failing at runtime if this is not the case.* Since an Expression could be almost anything then this could be a problem. For example, the following is valid code and would compile -
.Then(Identifier, x => null)
.. but it would fail at runtime. This is what I mean by it not being safe.
But I've got to admit, this approach has a certain charm about it! Maybe it's not an appropriate mechanism for critical life-or-death production code, but for building a little parser for a personal project.. maybe I could convince myself it's worth it!
(Credit where it's due, I think I first saw this specify-a-property-with-an-Expression technique some years ago in AutoMapper, which is an example of code that is often used in production despite not offering compile-time guarantees about mappings - but has such convenience that the need to write tests around the mappings is outweighed by the benefits).
* (Other people might also point out that reflection is expensive and that that is a major downside - however, the code that is used here is fairly easy to wrap up in LINQ Expressions that are dynamically compiled so that repeated executions of hot paths are as fast as hand-written code.. and if the paths aren't hot and executed many times, what's the problem with the reflection being slower??)
Posted at 00:10
A. | http://www.productiverage.com/Archive/8/2015 | CC-MAIN-2017-13 | refinedweb | 5,981 | 51.89 |
I have seen this happen before, but it seems to be a habit on the Quality Portal: getting rid of bugs by marking them as “new feature”:
[WayBack] I’m using THTTPClient.BeginGet() to create an async get request to a webservice that holds a connection open until it has data to return (sort of like a… – Brian Ford – Google+. which basically was another person finding out about [RSP-20827] THTTPClient request can not be canceld – Embarcadero Technologies, which got marked (a month after submission!) as “Issue is reclassified as ‘New Feature'”.
I get why it happens (there was something exposed, but some of the functionality is missing a feature which needs to be added).
Marking it as such however sends the wrong signal to your users: we do not see bugs as bugs, so they get on the “new feature” pile with no estimate on when the feature will be done.
–jeroen | https://wiert.me/category/development/software-development/issuebug-tracking/ | CC-MAIN-2019-26 | refinedweb | 153 | 63.02 |
Created on 2013-10-03.14:36:59 by cdleonard, last changed 2014-07-09.23:59:24 by zyasoft.
Sample printer.sh:
#! /bin/bash
for i in `seq 10`; do
echo -n O >&1
echo -n E >&2
done
Sample subproc_call.py:
#! /usr/bin/python
import subprocess
subprocess.call('./printer.sh')
When running subproc_call.py with cpython the output is always OEOEOEOEOEOEOEOEOEOE, as expected. When running with jython the output is usually OOOOOOOOOOEEEEEEEEEE but other variants are also possible.
The documentation of subprocess.Popen states by default "no redirection will occur; the child’s file handles will be inherited from the parent". Jython behaves differently in a way that introduces visible behavior changes.
Jython Popen with stdout=subprocess.PIPE and stderr.subprocess.STDOUT apparently behaves as expected. This can also happen if entire lines are printed, or with manual flushes. The following cpython print script also reproduces the issue:
#! /usr/bin/env python
import sys
for i in range(50):
sys.stdout.write('O\n')
sys.stdout.flush()
sys.stderr.write('E\n')
sys.stderr.flush()
This is a known issue: the original problem was subprocess was built for Jython 2.5 which ran on a minimum Java 5. There's no easy way to have a child process to inherit file handles from the parent w/ pure Java on Java 5 or 6
Java 7 finally added support for this
by 'no easy way' I meant 'no way' (w/ pure Java) =]
Should be an easy fix now that we require Java 7 by using inheritIO:
Target beta 4
I'm not certain how to test in a cross platform fashion, but this is a straightforward fix. | http://bugs.jython.org/issue2096 | CC-MAIN-2016-44 | refinedweb | 278 | 59.5 |
Red Hat Bugzilla – Bug 239899
pygame 64 bit bug, result: AttributeError: event member not defined
Last modified: 2007-11-30 17:12:04 EST
Hi, Hans.
I installed seahorse-adventures earlier and I thought I'd try it out, but it
fails to start every time I attempt to play it. The python traceback it gives is
as follows:
$ seahorse-adventures
Traceback (most recent call last):
File "/usr/bin/seahorse-adventures", line 32, in <module>
main.main()
File "/usr/share/seahorse-adventures/lib/main.py", line 314, in main
g.run(l)
File "/usr/share/seahorse-adventures/lib/pgu/engine.py", line 108, in run
self.loop()
File "/usr/share/seahorse-adventures/lib/pgu/engine.py", line 126, in loop
if not self.event(e):
File "/usr/share/seahorse-adventures/lib/main.py", line 262, in event
self.fnc('event', event)
File "/usr/share/seahorse-adventures/lib/pgu/engine.py", line 80, in fnc
if v != None: r = f(v)
File "/usr/share/seahorse-adventures/lib/menu.py", line 119, in event
if e.type is USEREVENT and e.action == 'down':
AttributeError: event member not defined
Version-Release number of selected component (if applicable):
seahorse-adventures-1.0-1.fc7.noarch
How reproducible:
Always
Steps to Reproduce:
1. Run `yum install seahorse-adventures` (as root)
2. Run `seahorse-adventures`
3. ???
4. Profit!!
Actual results: It crashes as explained above.
Expected results: I'd like to be able to play it. :)
Additional info: This is on an updated Fedora Development box (x86_64 only, no
multilib/32-bit stuff). I also tried to run it as root, but it still fails in
that case.
Thanks.
Hehe,
Good catch! I didn't see this myself as I developed this package on a 32 bit
machine. But since this package is 100% python, that shouldn't make a difference.
However there are a couple of 64bit bugs in pygame, one of which get triggered
by seahorse-adventures.
Chris, re-assigning to you. I know you only do pygame because its a dep of some
of your other packages, but no worries I've got a patch ready for you.
Created attachment 154584 [details]
PATCH: fixing 64 bit bugs
As promised, as you can see its a pretty simple patch, with the chance for
regressions being very close to 0. So please do a new pygame package with this
asap, and mail [email protected] with a request to tag the new pygame
for F7 final inclusion (I wouldn't mind receiving a CC).
Notice that this patch should NOT be used in FC-6, the involved python C api
functions got their prototype changed to take Py_ssize_t pointers (which point
to 64 bit vars on 64 bit machines) instead of int pointers in 2.5, for python
2.4 to current pygame code using int's for this is correct!
Thanks for the patch, Hans! It works nicely here. :D
I checked out a copy of pygame/devel from CVS and appended your patch to the
pygame-1.7.1-64bit.patch already in the CVS tree (changing the paths to all
start at src/ instead of pygame-1.7.1release/src/) and after rebuilding it, I no
longer have this issue with seahorse-adventures. (Hopefully this fixes a bunch
of other 64-bit holes too should any further arise...)
can you please test the -13 release in CVS? I can probably go ahead and push
it, but I'd rather you give it a test first to make sure everything is good. I
have to get rel-eng approval? Why can't I just make tag build?
(In reply to comment #4)
> can you please test the -13 release in CVS? I can probably go ahead and push
> it, but I'd rather you give it a test first to make sure everything is good.
Thanks very much for committing this, Chris. I checked-out a copy of the -13
release and built a local pygame RPM for myself, and it works just fine with
seahorse-adventures and manicor (though manicor worked fine before this patch,
if it makes a difference).
> I have to get rel-eng approval? Why can't I just make tag build?
IIRC, You can push it through the build system, but it won't hit the rawhide
composes or f7-final until after Fedora 7 goes GA. I've been rather absent from
Fedora for most of the merger stuff though; and am still learning my way through
it, reading mails/wiki about it, etc.
Okay, well I pushed the -13 release out and asked them to include this version
in F7. However, just after doing this I noticed another patch someone just
He claims his patch is better because it does something with rectangles, do you
think it is worth applying the extra changes?
Chris,
I've only briefly perused the patch he posted; but it seems to me that the
changes made by his patch are equivalent in function to the ones already posted
by Hans and what you've earlier had in CVS.
The rectangle changes, though, puzzle me quite a bit. All he did was remove the
type-casting from each of the methods. :|
Also, his patch effectively removes the Python 2.5-only snippets with
#ifdef/#endif preprocessor statements if building against 2.4, but since you're
only applying the patch to the devel branch (which has Python 2.5), this doesn't
seem a necessary feature. (Though it is likely highly necessary for the upstream
package until all vendors move up to Python 2.5 stuff.)
Hans? :)
I've reviewed the pythonmailinglist patch, mostly its the functional equivalent
of mine, it gets rid of some warnings. It does however contain one more 64 bit
fix which might be significant. So I think while were at it it would be good to
switch to this patch instead.
okay, sorry I missed that one bit. Should be fixed now, can you test the -14
release in CVS? Thanks.
(In reply to comment #9)
> okay, sorry I missed that one bit. Should be fixed now, can you test the -14
> release in CVS? Thanks.
The -14 release seems fine from my local testing. At least, I can't find any
regressions from the -13 release.
Thanks for your quick response, Chris & Hans!
okay, im going to go ahead and push this then, thanks :) | https://bugzilla.redhat.com/show_bug.cgi?id=239899 | CC-MAIN-2017-30 | refinedweb | 1,070 | 75.61 |
Customizing roles
If you are using the roles that are predefined in the Cognos namespace, you can customize themes, home pages, and report parameters that are unique to each Cognos role.
You can specify that a customized home page, or a particular report or dashboard, be displayed when a user with a particular Cognos role opens IBM® Cognos® Analytics. You may want to remove default user interface features for roles. In addition, you can customize parameters that can be used across reports and tailor them for each user role.
Before setting customized themes and home pages (other than a dashboard or report) you must have created and uploaded custom themes or home pages. For more information, see Customizing Cognos Analytics across all roles.
To customize individual roles, from
menu and select
Properties, the slide-out panel for that role has a
Customization tab.
Setting a default home page
Click
next to the default home page. You can
now browse for a dashboard or report to be the default home page, or you can select a view in the
list of views to be the default home page for all users in this role.
Removing or including features
You can choose user interface features to remove or include for users in a role. Click
next to Features. A list of
views is displayed. This list includes both the built-in views and any custom views that have been
uploaded. Click a view to see a high-level grouping of features for the view. Click
next to a grouping to drill-down to a lower level of
features. You can deselect or select any features in this list, or drill-down to another set of
features to choose from. Click Apply to save your changes. You can revert
your changes by clicking Reset to defaults.
To customize the navigation menu in reporting, expand.
Setting a default theme
Click
next to the default theme. You can
select a theme in the list of themes to be the default theme for all users in this role.
Creating a custom folder
Click
next to Custom
folder to set a custom content folder for users who have this role. When a user with
this role logs in, the custom folder is displayed on the navigation bar below Team
content.
Setting the default location for uploaded files
Click
next to Default upload
location to specify a folder in Team content as the default
location for uploaded files for users who have this role.
Setting default parameters for roles
Click Settings next to Parameters. A list appears of parameters that you customized. Choose the parameters that you want to configure for the role. Then select the default values that you want to appear for all users in this role. Click Apply then OK when you are done.
For more information, see Using customized parameters.
Resolving conflicts when a user has multiple roles
A user may have multiple roles which can have different default themes or home pages. To resolve this issue, when setting customizations for a role, click Advanced and set a priority for the role ranging from 0 to 10. In the case of a conflict the customizations for the role with the highest priority are used. The System Administrators role has a hard-coded priority of 1000. | https://www.ibm.com/docs/en/cognos-analytics/11.1.0?topic=namespace-customizing-roles | CC-MAIN-2021-17 | refinedweb | 551 | 63.7 |
Every filesystem on the appliance must be given a unique mountpoint which serves as the access point for the filesystem data. Projects can be given mountpoints, but these serve only as a tool to manage the namespace using inherited properties. Projects are never mounted, and do not export data over any protocol.
All shares must be mounted under /export. While it is possible to create a filesystem mounted at /export, it is not required. If such a share doesn't exist, any directories will be created dynamically as necessary underneath this portion of the hierarchy. Each mountpoint must be unique within a cluster.
It is possible to create filesystems with mountpoints beneath that of other filesystems. In this scenario, the parent filesystems are mounted before children and vice versa. The following cases should be considered when using nested mountpoints:
If the mountpoint doesn't exist, one will be created, owned by root and mode 0755. This mountpoint may or may not be torn down when the filesystem is renamed, destroyed, or moved, depending on circumstances. To be safe, mountpoints should be created within the parent share before creating the child filesystem.
If the parent directory is read-only, and the mountpoint doesn't exist, the filesystem mount will fail. This can happen synchronously when creating a filesystem, but can also happen asynchronously when making a large-scale change, such as renaming filesystems with inherited mountpoints.
When renaming a filesystem or changing its mountpoint, all children beneath the current mountpoint as well as the new mountpoint (if different) will be unmounted and remounted after applying the change. This will interrupt any data services currently accessing the share.
Support for automatically traversing nested mountpoints depends on protocol, as outlined below.
Regardless of protocol settings, every filesystem must have a mountpoint. However, the way in which these mountpoints are used depends on protocol.
Under NFS, each filesystem is a unique export made visible via the MOUNT protocol. NFSv2 and NFSv3 have no way to traverse nested filesystems, and each filesystem must be accessed by its full path. While nested mountpoints are still functional, attempts to cross a nested mountpoint will result in an empty directory on the client. While this can be mitigated through the use of automount mounts, transparent support of nested mountpoints in a dynamic environment requires NFSv4.
NFSv4 has several improvements over NFSv3 when dealing with mountpoints. First is that parent directories can be mounted, even if there is no share available at that point in the hierarchy. For example, if /export/home was shared, it is possible to mount /export on the client and traverse into the actual exports transparently. More significantly, some NFSv4 clients (including Linux) support automatic client-side mounts, sometimes referred to as "mirror mounts". With such a client, when a user traverses a mountpoint, the child filesystem is automatically mounted at the appropriate local mountpoint, and torn down when the filesystem is unmounted on the client. From the server's perspective, these are separate mount requests, but they are stitched together onto the client to form a seamless filesystem namespace.
The SMB protocol does not use mountpoints, as each share is made available by resource name. However, each filesystem must still have a unique mountpoint. Nested mountpoints (multiple filesystems within one resource) are not currently supported, and any attempt to traverse a mountpoint will result in an empty directory.
Filesystems are exported using their standard mountpoint. Nested mountpoints are fully supported and are transparent to the user. However, it is not possible to not share a nested filesystem when its parent is shared. If a parent mountpoint is shared, then all children will be shared as well.
Filesystems are exported under the /shares directory, so a filesystem at /export/home will appear at /shares/export/home over HTTP/HTTPS. Nested mountpoints are fully supported and are transparent to the user. The same behavior regarding conflicting share options described in the FTP protocol section also applies to HTTP. | https://docs.oracle.com/cd/E26765_01/html/E26397/shares__filesystem_namespace.html | CC-MAIN-2018-09 | refinedweb | 662 | 54.52 |
Problem
Given an array of size n consisting of positive integers. There are m persons. Each person can eat one integer at a time, where the time taken by each to eat the integer is equal to the value of the integer. It is given that the m persons can eat k integers together and divide the integer equally amoung themselves, reducing the time taken to eat the integer to (a1+a2+...+ap) / m, where p <= k.
For example :
If the integers are [ 1, 3 , 5 , 8 ], m = 4 and k = 1, the one of the ways by which the 4 people could eat the integers could be, to have one inetegr each, in which the total time would be 1 + 3 + 5 + 8 = 17. Another way could be to feed all four people the integer 8, as the limit is 1, and so the total time would be 1 + 3 + 5 + (8/4) = 11, which is also the minimum time which the 4 people could have taken to eat all the integers.
Given, n, m, k and the list of all n integrers, find the minimum possible time in which the integers can be eaten up.
My Solution
My approach was to first sort the array in non-decreasing order, and start a recursive search from (N-1)th index. At each recursive I would have two branches, in one I would assume the current element was eaten by just one person, and in the other branch add the value to the sum of all integers which will be eaten by all m people, and also reduce the value of k by 1 in the next recursive call. Then in the base case of (k == 1 || index = -1), assume all remaining elements to be eaten by a single person, and return (sum + batch_eating_sum / m ) only if batch_eating_sum can be equally divided among all m, if not, add them to the sum as well assuming all are being eaten by one person each. I also take min of both the branches.
This solution seems fine to me. But I'm afraid this seems to be an O(2n) solution, and n can be as large as 105, so this might fail in those cases.
I was then thinking of two possible approaches :
- One could be to keep a track of recursive calls which we have already seen, and not compute them again, but I can't seem to figure out what they exactly are.
- I then though if this problem could be boiled down to somthing like number of subsets of an array which add up to a number S, which in this case could be, subsets of length <= k which are a multiple of m.
But, I couldn't make any progress in any of the two.
Do let me know your views on what your approach would have been !
Thanks ! | http://codeforces.com/topic/95660/?locale=ru | CC-MAIN-2022-05 | refinedweb | 482 | 70.26 |
Although I fully recommend using Application Insights (see here) for monitoring your Azure features, I get asked sometimes how to configure log4net onto an Azure App Service. So, this is how I did it.
- Install the log4net.dll binary using NuGet
- Configure the log4net name, type properties in the web.config
- Configure the log4net properties
- Modify the Global.asax Application_Start() method
- Create an instance of the ILog interface
- Create the directory on KUDU/SCM
- Write the logs
- Download and analyze
I updated a project I wrote about here to use the log4net capability. I wanted to put it into my ASP.NET Core application, however it seems like it is not yet supported, at least while I was creating this one. Therefore, integrated log4net into the Azure Apps Service that consumes the ASP.NET Core Web API instead of within the API itself.
Install the log4net.dll binary using NuGet
Install the log4Net (add the reference) by right-clicking on the project –> Manage NuGet packages. Then search for and install the log4net binaries, as seen in Figure 1.
Figure 1, install log4net binaries for use with an Azure App Service
Configure the log4net name, type properties in the web.config
Add the <configSections> attribute to the web.config file between the already existing <configuration> attribute.
<configuration> <configSections> <section name="log4net" type="log4net.Config.Log4NetConfigurationSectionHandler,Log4net"/> </configSections> </configuration>
Configure the log4net properties
Add this configuration directly after the one added in the previous section
<log4net> <root> <level value="Debug"/> <appender-ref </root> <appender name="LogFileAppender" type="log4net.Appender.RollingFileAppender"> <param name="File" value="D:\Home\LogFiles\Log4Net\Log4Net.log"/> ="SleepyCore"> <level value="INFO"/> </logger> </log4net>
A few of the configurations I would like to call out are:
- “File” with a value of “D:\Home\LogFiles\Log4Net\Log4Net.log” – have a look at my other post here where I discuss the file structure of an Azure App Service. Note that although you can read from and write to the D:\local directory (using FileZilla, for example), it does not mean your application can. But your application can write to the D:\home\LogFiles\*.
- “maximumFileSize” – it is always a good idea to set this so you do not run out of drive space, plus, if/when the file gets very large it can cause performance issues
- “logger name=’SleepyCore’” – this needs to match the parameter I pass to the GetLogger() method later in the “Create an instance of the ILog interface” section
- “level value=’INFO’” – will inform the logger that I want calls to log.Info() to be written to the log, see section “Write the logs”. If the value was set to Debug or Error, then the Info calls would not be logged.
Modify the Global.asax Application_Start() method
Add the instantiation of the log4net features to the Global.asax file. This is kind of ‘old school’ but it does work. Also, consider adding some code in the Application_Error() method as well to log any application error.
<%@ Import void Application_Start(object sender, EventArgs e) { log4net.Config.XmlConfigurator.Configure(new FileInfo(Server.MapPath("~/Web.config"))); } void Application_Error(object sender, EventArgs e) { ILog log = LogManager.GetLogger("SleepyCore"); Exception ex = Server.GetLastError(); log.Debug("++++++++++++++++++++++++++++"); log.Error("Exception - \n" + ex); log.Debug("++++++++++++++++++++++++++++"); } </script>
Create an instance of the ILog interface
In the Default.aspx.cs file I added the following.
using log4net; public partial class _Default : System.Web.UI.Page { private static readonly ILog log = LogManager.GetLogger("SleepyCore"); ... }
Create the directory on KUDU/SCM
I wrote an article here about accessing KUDU/SCM. Once you login, click on the the Debug console –> CMD and navigate to the D:\Home\LogFiles directory and then create a folder named Log4Net, Figure 2, or one that matches the ‘File’ value you set in the “Configure the log4net properties” earlier. This is the place where the log file will be written to.
Figure 2, create Log4Net directory on KUDU/SCM azure app service
Write the logs
In my consumer code, I added code within the Page_Load() method, similar to the following.
protected void Page_Load(object sender, EventArgs e) { try { log.Info("Begin - Page_Load() at " + DateTime.Now.ToString("hh.mm.ss.ffffff")); log.Info("------------------------------------------------------------------"); ...... log.Info("Begin - request.GetResponse() at " + DateTime.Now.ToString("hh.mm.ss.ffffff")); System.Net.WebResponse response = request.GetResponse(); log.Info("End - request.GetResponse() at " + DateTime.Now.ToString("hh.mm.ss.ffffff")); ..... log.Info("------------------------------------------------------------------"); log.Info("End - Page_Load() at " + DateTime.Now.ToString("hh.mm.ss.ffffff")); } catch (Exception ex) { labelAPI.Text = ex.Message; log.Debug("++++++++++++++++++++++++++++"); log.Error("Exception - \n" + ex); log.Debug("++++++++++++++++++++++++++++"); } }
Simply paste the code around any method you would like to track for time. If your methods contain parameters, you can also dump out the values of them with each method call.
Notice that I use the log.Info(), log.Debug() and log.Error(). In order for the log.Info() method to trigger I must set the logger value to INFO, see section “Configure the log4net properties”. If this value is set to Debug or Error, then the calls to the log.Info() method will not fire and will not be written to the log.
Once the code is deployed and the Page_Load() method is called, a log is written in the defined format and in the defined location, see Figure 3.
Figure 3, log Log4Net for an azure app service
Download and analyze
You can download the logs using FileZilla or any FTP tool, or you can download them from KUDU/SCM by clicking the download button also shown in Figure 3.
I looked for some tools to analyze these logs, but as they are uniquely configurable, I was unable to find a tool which could manage them, honestly did not spend a lot of time looking, as there are so many better ways to get insights into the operations of your application. | https://blogs.msdn.microsoft.com/benjaminperkins/2017/09/27/how-to-configure-log4net-on-azure-app-service/ | CC-MAIN-2018-47 | refinedweb | 969 | 57.37 |
How to Embed ViewCVS in Plone
An example of how to 'persuade' ViewCVS to embed in a Plone page. Provides an account of how to do rewriting with Apache, converting ViewCVS, and adding externally created, dynamic content to Plone pages.
The original content of this how-to can be found at this location.
A working example can be found at this location.
I can't just paste the code, since your setup will be different from mine. And beware for those who want elegance, this is not the epitome of pretty code. It is just a plain quick hack that took under 2 hours to implement. I have no doubt this How-To will take me at least double that length of time. Furthermore, my deepest respect to the ViewCVS team for an excellent product. I am sorry that I had to do what I did to get it to work how I wanted it to. I would send you a patch but I am far too scared. And last but not least, Plone and Zope, absolutely killer products from the minds of geniuses.
The nature of the problem
The nice thing about Plone, and I have only been using it for 4 days, is that everything looks the same. I think the Human Computer Interface Designers would call this something like uniformity and consistency , and for me as the end user it is just lovely.
That is all well, but what about prepackaged scripts that don't look like plone, how can you embed them in a Plone page? ViewCVS is one such script. It is used almost universally for displaying CVS contents with HTML over HTTP for example. Incredibly, and if you checked the link, you will see that even Sourceforge display a naked ViewCVS page with no formatting. Yuck!
How are we going to fix it?
Well, there are about 14,000 solutions to this problem, and I really should have approached it in one of the other ways (like importing the mod-python viewcvs modules and using them, or even calling the cgi scripts directly) but instead, I decided to use my existing Apache based viewcvs setup.
I shall force viewCVS requests to be passed to a Zope request-handler which will independently request the actual ViewCVS content and embed it in a plone page.:
USER -> APACHE -> REWRITE -> ZOPE -> VIEWCVS(APACHE) -> ZOPE -> USER
Well that is it. If you understand that, you are done with this how-to. If you need more information on some or all of the steps that it took (and remember doing it takes very little actual time) please read on.
Requirements
- ViewCVSNote: you will not be able to run this copy of ViewCVS outside Plone after these changes, you will need to use another copy
- Plone
- Zope
- Apache with Rewrite and Proxy modules
Apache Rewriting
The plan is to have all requests to the root
/ on the server to be redirected to the Plone (Zope) server, while all requests to
/local/ to be allowed to pass through to Apache. I understand this is a very common way of using Zope and Plone, and it certainly works fairly smoothly on my set up.
I am barely literate in Apache mod-rewrite, but the best I can do is to paste my example configuration and explain it. If you alreday have rewrite set up, you may need to review your config to see exactly what is going on.:
RewriteEngine On RewriteRule ^/local - [L] RewriteRule ^/(.*) [P]
The first line turns rewriting on. The second line tells the server to stop processing and pass through to the local server
- [L] any requests to
/local. And the third line rewrite all other requests to that weird url on the local machine. If you don't know what they all mean, don't worry, just know that
localhost:8080 is the location of the Zope server, and
aa.homelinux.com:80 is the location of the Apache Server. Leave the other words as they are. They are needed by the virtual host monster.
Do it now, install a virtual host monster in the root of your Zope installation. It is in the dropdown box on the right. You don't need to edit this in any way. And while you are at it, if you have changed any Apache settings, restart the server.
ViewCVS
Currently, I have an alias for
/local/cvs/ which points to my actual viewcvs directory using Apache2. If you haven't already set it up, a simple alias like this will usually do the job for making ViewCVS work with Apache:
Alias /local/cvs /usr/lib/cgi-bin/viewcvs.cgi
Where
/local/cvs/ is the browseable url for ViewCVS on the Apache server, and
/usr/lib/cgi-bin/viewcvs.cgi is the actual location of ViewCVS on your filesystem. Before I put Plone in the mix, this is how the outside world would access ViewCVS.
When ViewCVS renders it's pages it sets up the url for the link and in our case it sets them up as:
<servername>/<script location>/<parameters>
In order that we can force ViewCVS to change its links to point to:
<servername>/<our Plone proxy>/<parameters>/
we must edit the code. The creation of the Plone proxy is discussed below. It is responsible for fetching actual ViewCVS pages and making them look Plone.
Editing your exact code may be different, my version is 1.0-dev from Debian Unstable. You need to find the main ViewCVS module, called
/usr/lib/python2.3/site-packages/viewcvs/viewcvs.py on my installation. At approximately line 403, in the method get_link(), I have changed:
url = self.script_name
to:
url = '/cvs/vcvsproxy'
or the location of a page template in your Plone site, eg /Portal/vcvsproxy from where you want to serve the ViewCVS Content.
(further elements are added to this url by the method)
Thus, if original links had been created to:
<servername>/local/cvs/<parameters>
they would now point to:
<servername>/cvs/vcsproxy/<parameters>
Check the change has worked. Refresh a ViewCVS page, and click on a link. They should all be broken and point to a zope page that isn't there. If they are broken, examin the links. Are they of the correct type discussed above? I repeat, your installation may be different from everyone else's, so examine them carefully. If you are done, you should now move on to creating the Plone proxy, a dynamic piece of Plone content.
Plone Basic Content Embedding
Did you remember to install a virual host monster in the root folder of your Zope?
You would expect that it is easy to make a random HTML page look like a Plone page from within a Plone site. You would be right, it is easy.
You have to:
- Create a page template.
- Set the default template for that form to be the template used by Plone.
- Add some kind of content to the page.
Creating a page template
Excuse me if you already know how to do this! Go to the drop down box on the left in the Zope Management Interface (usually at /manage on your Zope installation) and select "page template". You will be asked for an ID and set this to
vcvsproxy or the value that you entered above for the new ViewCVS URLs.
Ok, done! Check it worked. Browse your Plone site to the ID of your newly added page template, and you should see the defualt template in place.
Setting the page template to use the default Plone template
Edit your newly created page template and in it's
<html> tag insert:
metal:use-macro="here/main_template/macros/master"
As you can probably see, this will make the page template use the default Plone template (here/main_template).
Ok, done! Check it worked. Browse the page again, and this time it should miraculously look like a Plone page.
Adding content to the page
There are a few ways which you can add content to this page and there are surely more that I will discover with time.
- Static content. This is the easiest way, and not much use to anyone! Frankly if you want to add a static content page to your Plone, do it through the web interface and write it in structured text. Exactly like I am doing right now.
- Dynamic content. This content can come from a number of sources. The two I have become familiar with are the "script (Python)" and the "external method". Both of these are python scripts. The difference between them is how you use them (although I am no expert) "script (python)" lives inside the Zope insance and can really only access components of the instance itself. It certainly cannot do things like import modules or open external files. It is probably much faster for this. External methods are methods within python modules that live outside the Zope insance and are capable of doing everything that Python can in terms of library imports. Thus you can do funky things like open files, or even as we shall see open external web-pages.
In the body of your page template you need to insert the tags:
<div metal: <span tal: </div>
- The outer
<div>element indicates that we would like the content to fill the main slot, the main content area of the page:
metal:fill-slot="main"
- The inner
<span>element indicates that it would like itself replaced by the output of here/foo with:
tal:replace="structure here/getcvs".
getcvsis the name of the script or external method we shall be calling. This guarantees that the external method will return an HTML-formatted string which will be embedded at the requested position in the page. (Note: for an External Method, this is the ID of the method itself, not the module within which it is).
External Methods
We will concentrate on External methods since we will be using one later. You will need to:
- Create the python module.
- Add the method to the Plone site.
Creating the Python module
Call it whatever you like with the extension .py (beware Windows users!). For our example we shall call it
cvs.py. Your installation may differ from mine - the location of the module. I put mine in
/var/lib/zope/instance/default/Extensions, and I am assured that this is a good place for it. It must be in the Extensions directory of your instance on your filesystem. You need one method at least in this module that takes an optional parameter (which we shall call
self but as a note for Python programmers, this is not an instance of the method) and which will return a string. We shall call our method
getcvs. At this stage we don't know what we are going to need in our module, we will just put in a test. Your module should look like this:
def getcvs(self): return "<h1>Hello Plone World</h1>"
Adding the external method to your Plone site
In the dropdown box, select External Method. Enter the following options:
ID getcvs TITLE The ViewCVS Fetcher MODULE NAME cvs FUNCTION NAME getcvs
And you are done. Remember this page, you need to reload the method every time you make a change of it just by uploading the file again. Check the script works, by browsing the URL of your vcvsproxy. It should return you a Plone looking page greeting you with the message
Hello Plone World entered above. If so you have the script working, so you can move on to actually making it useful.
Fetching ViewCVS content with a Python External Method
You have a working external method (getcvs) that is called by a Plone-looking page-template (vcvsproxy) for its content. You external method may differ from mine. Mine is probably appalling code, but it almost works. The general idea is to:
- Parse the request to the vcvsproxy for the parameters to pass to ViewCVS
- Construct a new URL which is the actual location of ViewCVS on the system (in my case /local/cvs/*).
- Connect and read the headers for the new URL.
- If it is an text/html page, return it's contents back to the page template that called the method.
- I it is any other file, return a page containing a link to the actual location of the file so that users may click it to download.
Happy? Let's have a look at the code:
import urllib2 def getcvs(self): # self is an object passed to us. You can query it with dir() if you # like, split the path requested, and grab the bit after '/vcvsproxy/' p = self.REQUEST.PATH_INFO.split('vcvsproxy')[-1] # build the new actual URL to ViewCVSdownload</a> """ RT = """ %s <a href=""> How to embed ViewCVS in Plone </a> """
Well, you won't believe it, but you are done!
Test your setup. Browsing vcvsproxy/ should give you the CVS root. If you would like to see an example of this working, please visit my CVS Repository.
Alternative: mxmProxy
It also fetches content from a different site, but it provides some nice features to parse and encode it properly as well. | http://plone.org/documentation/how-to/embed-viewcvs-in-plone | crawl-002 | refinedweb | 2,199 | 71.04 |
Pandas Data Series: Check inequality over the index axis of a given dataframe and a given series
Pandas: Data Series Exercise-40 with Solution
Write a Pandas program to check inequality over the index axis of a given dataframe and a given series.
Sample Solution :
Python Code :
import pandas as pd df_data = pd.DataFrame({'W':[68,75,86,80,None],'X':[78,75,None,80,86], 'Y':[84,94,89,86,86],'Z':[86,97,96,72,83]}); sr_data = pd.Series([68, 75, 86, 80, None]) print("Original DataFrame:") print(df_data) print("\nOriginal Series:") print(sr_data) print("\nCheck for inequality of the said series & dataframe:") print(df_data.ne(sr_data, axis = 0))
Sample Output:
Original DataFrame: W X Y Z 0 68.0 78.0 84 86 1 75.0 75.0 94 97 2 86.0 NaN 89 96 3 80.0 80.0 86 72 4 NaN 86.0 86 83 Original Series: 0 68.0 1 75.0 2 86.0 3 80.0 4 NaN dtype: float64 Check for inequality of the said series & dataframe: W X Y Z 0 False True True True 1 False False True True 2 False True True True 3 False False True True 4 True True True True
Python Code Editor:
Have another way to solve this solution? Contribute your code (and comments) through Disqus.
Previous: Write a Pandas program to find the index of the first occurrence of the smallest and largest value of a given series.
Next: Python Pandas Data Series, DataFrame Exercises | https://www.w3resource.com/python-exercises/pandas/python-pandas-data-series-exercise-40.php | CC-MAIN-2021-21 | refinedweb | 254 | 67.55 |
2. Writing the Setup Script¶
Note
This document is being retained solely until the
setuptools documentation
at
independently covers all of the relevant information currently included here.
A Simple Example A Simple Example: Additional meta-data.'))
2.1. Listing whole packages¶
The anyway..)
2.2. Listing individual modules¶
For a small module distribution, you might prefer to list all modules rather than listing packages—especially the case of a single module that goes in the “root package” (i.e., no package at all). This simplest case was shown in section A Simple Example;.
2.3. Describing extension modules¶
Just as writing Python extension modules is a bit more complicated than writing pure Python modules, describing them to the Distutils is a bit more complicated. Unlike pure modules, it’s not enough just to list modules or packages and expect the Distutils to go out and find the right files; you have to specify the extension name, source file(s), and any compile/link requirements (include directories, libraries to link with, etc.).
All of this is done through another keyword argument to
setup(), the
ext_modules option.
ext_modules is just a list of
Extension instances, each of which describes a
single extension module.
Suppose your distribution includes a single extension, called
foo and
implemented by
foo.c. If no additional instructions to the
compiler/linker are needed, describing this extension is quite simple:
Extension('foo', ['foo.c'])
The
Extension class can be imported from
distutils.core along
with
setup(). Thus, the setup script for a module distribution that
contains only this one extension and nothing else might be:
from distutils.core import setup, Extension setup(name='foo', version='1.0', ext_modules=[Extension('foo', ['foo.c'])], )
The
Extension class (actually, the underlying extension-building
machinery implemented by the build_ext command) supports a great deal
of flexibility in describing Python extensions, which is explained in the
following sections.
2.3.1. Extension names and packages¶
The first argument to the
Extension constructor is
always the name of the extension, including any package names. For example,
Extension('foo', ['src/foo1.c', 'src/foo2.c'])
describes an extension that lives in the root package, while
Extension('pkg.foo', ['src/foo1.c', 'src/foo2.c'])
describes the same extension in the
pkg package. The source files and
resulting object code are identical in both cases; the only difference is where
in the filesystem (and therefore where in Python’s namespace hierarchy) the
resulting extension lives.
If you have a number of extensions all in the same package (or all under the
same base package), use the
ext_package keyword argument to
setup(). For example,
setup(..., ext_package='pkg', ext_modules=[Extension('foo', ['foo.c']), Extension('subpkg.bar', ['bar.c'])], )
will compile
foo.c to the extension
pkg.foo, and
bar.c to
pkg.subpkg.bar.
2.3.2. Extension source files¶
The second argument to the
Extension constructor is
a list of source
files. Since the Distutils currently only support C, C++, and Objective-C
extensions, these are normally C/C++/Objective-C source files. (Be sure to use
appropriate extensions to distinguish C++ source files:
.cc and
.cpp seem to be recognized by both Unix and Windows compilers.)
However, you can also include SWIG interface (
.i) files in the list; the
build_ext command knows how to deal with SWIG extensions: it will run
SWIG on the interface file and compile the resulting C/C++ file into your
extension.
This warning notwithstanding, options to SWIG can be currently passed like this:
setup(..., ext_modules=[Extension('_foo', ['foo.i'], swig_opts=['-modern', '-I../include'])], py_modules=['foo'], )
Or on the commandline like this:
> python setup.py build_ext --swig-opts="-modern -I../include"
On some platforms, you can include non-source files that are processed by the
compiler and included in your extension. Currently, this just means Windows
message text (
.mc) files and resource definition (
.rc) files for
Visual C++. These will be compiled to binary resource (
.res) files and
linked into the executable.
2.3.3. Preprocessor options¶
Three optional arguments to
Extension will help if
you need to specify include directories to search or preprocessor macros to
define/undefine:
include_dirs,
define_macros, and
undef_macros.
For example, if your extension requires header files in the
include
directory under your distribution root, use the
include_dirs option:
Extension('foo', ['foo.c'], include_dirs=['include'])
You can specify absolute directories there; if you know that your extension will
only be built on Unix systems with X11R6 installed to
/usr, you can get
away with
Extension('foo', ['foo.c'], include_dirs=['/usr/include/X11'])
You should avoid this sort of non-portable usage if you plan to distribute your code: it’s probably better to write C code like
#include <X11/Xlib.h>
If you need to include header files from some other Python extension, you can
take advantage of the fact that header files are installed in a consistent way
by the Distutils install_headers.
You can define and undefine pre-processor macros with the
define_macros and
undef_macros options.
define_macros takes a list of
(name, value)
tuples, where
name is the name of the macro to define (a string) and
value is its value: either a string or
None. (Defining a macro
FOO
to
None is the equivalent of a bare
#define FOO in your C source: with
most compilers, this sets
FOO to the string
1.)
undef_macros is
just a list of macros to undefine.
For example:
Extension(..., define_macros=[('NDEBUG', '1'), ('HAVE_STRFTIME', None)], undef_macros=['HAVE_FOO', 'HAVE_BAR'])
is the equivalent of having this at the top of every C source file:
#define NDEBUG 1 #define HAVE_STRFTIME #undef HAVE_FOO #undef HAVE_BAR
2.3.4. Library options¶
You can also specify the libraries to link against when building your extension,
and the directories to search for those libraries. The
libraries option is
a list of libraries to link against,
library_dirs is a list of directories
to search for libraries at link-time, and
runtime_library_dirs is a list of
directories to search for shared (dynamically loaded) libraries at run-time.
For example, if you need to link against libraries known to be in the standard library search path on target systems
Extension(..., libraries=['gdbm', 'readline'])
If you need to link with libraries in a non-standard location, you’ll have to
include the location in
library_dirs:
Extension(..., library_dirs=['/usr/X11R6/lib'], libraries=['X11', 'Xt'])
(Again, this sort of non-portable construct should be avoided if you intend to distribute your code.)
2.3.5. Other options¶
There are still some other options which can be used to handle special cases.
The
optional option is a boolean; if it is true,
a build failure in the extension will not abort the build process, but
instead simply not install the failing extension.
The
extra_objects option is a list of object files to be passed to the
linker. These files must not have extensions, as the default extension for the
compiler is used.
extra_compile_args and
extra_link_args can be used to
specify additional command line options for the respective compiler and linker
command lines.
export_symbols is only useful on Windows. It can contain a list of
symbols (functions or variables) to be exported. This option is not needed when
building compiled extensions: Distutils will automatically add
initmodule
to the list of exported symbols.
The
depends option is a list of files that the extension depends on
(for example header files). The build command will call the compiler on the
sources to rebuild extension if any on this files has been modified since the
previous build.
2.4. Relationships between Distributions and Packages¶
A distribution may relate to packages in three specific ways:
It can require packages or modules.
It can provide packages or modules.
It can obsolete packages or modules.:
Now that we can specify dependencies, we also need to be able to specify what we
provide that other distributions can require. This is done using the provides
keyword argument to
setup(). The value for this keyword is a list of
strings, each of which names a Python module or package, and optionally.
2.5. Installing Scripts¶'] )
Changed in version 3.1: All the scripts will also be added to the
MANIFEST file if no template is
provided. See Specifying the files to distribute.
2.6. Installing Package Data¶
Often,']}, )
Changed in version 3.1: All the files that match
package_data will be added to the
MANIFEST
file if no template is provided. See Specifying the files to distribute.
2.7. Installing Additional Files¶
The'])], )
Each (directory, files) pair in the sequence specifies the installation directory and the files to install there.
Each file name in files is interpreted relative to the
setup.py
script at the top of the package source distribution. Note that you can
specify the directory where the data files will be installed, but you cannot
rename the data files themselves.
The directory should be a relative path. It is interpreted relative to the
installation prefix (Python’s
sys.prefix for system installations;
site.USER_BASE for user installations). Distutils allows directory to be
an absolute installation path, but this is discouraged since it is
incompatible with the wheel packaging format..
Changed in version 3.1: All the files that match
data_files will be added to the
MANIFEST
file if no template is provided. See Specifying the files to distribute.
2.8. Additional meta-data¶
The setup script may include additional meta-data beyond the name and version. This information includes:
Notes:
These fields are required.
It is recommended that versions take the form major.minor[.patch[.sub]].
Either the author or the maintainer must be identified. If maintainer is provided, distutils lists it as the author in
PKG-INFO.
The
long_descriptionfield is used by PyPI when you publish a package, to build its project page.
The
licensefield is a text indicating the license covering the package where the license is not a selection from the “License” Trove classifiers. See the
Classifierfield. Notice that there’s a
licencedistribution option which is deprecated but still acts as an alias for
license.
This field must be a list.
The valid classifiers are listed on PyPI.
To preserve backward compatibility, this field also accepts a string. If you pass a comma-separated string
'foo, bar', it will be converted to
['foo', 'bar'], Otherwise, it will be converted to a list of one string.
- ‘short string’
A single line of text, not more than 200 characters.
- ‘long string’
Multiple lines of plain text in reStructuredText format (see).
- ‘list of strings’
See below.:
- 0.1.0
the first, experimental release of a package
- 1.0.1a2
the second alpha release of the first patch version of 1.0
classifiers must be specified in a list:
setup(...,', ], )
2.9. Debugging the setup script¶
Sometimes things go wrong, and the setup script doesn’t do what the developer wants.
Distutils catches any exceptions when running the setup script, and print a simple error message before the script is terminated. The motivation for this behaviour is to not confuse administrators who don’t know much about Python and are trying to install a package. If they get a big long traceback from deep inside the guts of Distutils, they may think the package or the Python installation is broken because they don’t read all the way down to the bottom and see that it’s a permission problem.
On the other hand, this doesn’t help the developer to find the cause of the
failure. For this purpose, the
DISTUTILS_DEBUG environment variable can be set
to anything except an empty string, and distutils will now print detailed
information about what it is doing, dump the full traceback when an exception
occurs, and print the whole command line when an external program (like a C
compiler) fails. | https://docs.python.org/3/distutils/setupscript.html | CC-MAIN-2022-05 | refinedweb | 1,954 | 56.15 |
This blog entry is a lead in to a new series of articles about developing GUIs with the .NET Micro Framework.
A good place to start when learning a new GUI framework is to learn how to draw simple graphics. This blog entry discusses how to draw simple graphics with the .NET Micro Framework.
Creating a Bitmap
The Microsoft.SPOT namespace contains a Bitmap class which represents a bitmap image. To create a bitmap the same size as your physical screen you could use a code snippet such as the following:
using Microsoft.SPOT; using Microsoft.SPOT.Presentation; Bitmap bmp = new Bitmap(SystemMetrics.ScreenWidth, SystemMetrics.ScreenHeight);
Once you have a bitmap you can draw on it by using the various instance methods of the Bitmap class. When your drawing is completed, you need to copy the bitmap to the LCD screen in order for it to become visible. The framework provides a Flush() method to perform this task. Calling Flush() on your bitmap will copy the bitmap data to the LCD screen.
Bitmap bmp = new Bitmap(SystemMetrics.ScreenWidth, SystemMetrics.ScreenHeight); // ... do drawing stuff here ... bmp.Flush(); // copy bitmap to LCD
It is important to note that to use the Flush() method your bitmap must be exactly the same size as the LCD display. Otherwise the flush will simply not work, even though no exception or debug diagnostic will indicate a problem while debugging. This is a common trend with many of the .NET Micro Framework Base Class Library methods.
Representing Colours
A colour is represented by the Color enumeration found within the Microsoft.SPOT.Presentation.Media namespace.
This enumeration only has the values Black and White pre-defined. For example to specify the colour White you could use a code snippet such as the following:
using Microsoft.SPOT.Presentation.Media; Color white = Color.White;
It is possible to specify other colours by specifying the red, green and blue intensity values that make up the desired colour. To do this you use a static method within the ColorUtility class called ColorFromRGB as shown below:
using Microsoft.SPOT.Presentation.Media; // Specify full intensity red Color red = ColorUtility.ColorFromRGB(255, 0, 0);
The parameters passed to ColorFromRGB are the Red, Green and Blue components of the desired colour. These values are all bytes which range from 0 to 255 (full brightness).
ColorFromRGB basically encapsulates some simple bit shifts and a typecast. Internally the .NET Micro Framework represents colours as 3 8bit fields packed into a single 32bit unsigned integer. Instead of using the ColorFromRGB method we can perform a manual typecast between a suitable number and the Color enumeration as follows:
using Microsoft.SPOT.Presentation.Media; // 0xBBGGRR Color red = (Color)0x0000FF;
The format when the value is expressed in hexadecimal is 0xBBGGRR, i.e. 8 bits red (R), 8 bits green (G), followed by 8 bits blue (B). So the above example creates a red colour with full intensity.
Drawing Shapes
The bitmap class has numerous methods available for drawing the outlines of basic shapes such as lines, rectangles and ellipses.
- Drawing lines:
// Draw a red line 10 pixels thick // between (x=20, y=30) and (x=40, y=50). bmp.DrawLine(red, // colour 10, // thickness 20, // x0 30, // y0 40, // x1 50) // y1;
A line is specified by providing the colour, thickness and start and end co-ordinates of the line. The current implementation of the .NET Micro Framework base class library appears to ignore the thickness parameter, all lines are drawn 1 pixel wide.
- Drawing rectangles:
// Draw a rectangle which is 40 pixels // wide and 50 pixels high. The top left // corner is at (x=20, y=30). The outline is // 10 pixels wide in red. bmp.DrawRectangle(red, // outline colour 10, // outline thickness 20, // x 30, // y 40, // width 50, // height 0, // xCornerRadius, 0, // yCornerRadius, 0, 0, 0, 0, 0, 0, 0);
Drawing a rectangle involves using the DrawRectangle method which potentially requires setting a number of parameters. We will initially ignore the last 7 parameters and set them to zero (we will discuss them later when we cover gradient fills.).
If the outline thickness is greater than 1 then the co-ordinates specified indicate the center of the outline, i.e. half the outline is drawn on each side.
Rectangles with rounded corners can be specified by setting the xCornerRadius and yCornerRadius parameters to the desired radius. If the radius is larger than zero the outline thickness is ignored by the current version of the BCL and the framework reverts to drawing a 1 pixel thick outline.
- Drawing Ellipses:
// Draw an ellipse centred at (x=30, y=60) // with a radius of 10 on the x axis and // 20 on the y axis. bmp.DrawEllipse(red, // colour 30, // x 60, // y 10, // x radius 20); // y radius
The simplest way to draw an ellipse is to specify the colour, center co-ordinates, and then the radiuses for the x and y axis respectively. This allows drawing not only ellipses, but also circles (which simply have the x and y radiuses the same).
There is a more complex overload of the DrawEllipse method which enables you to specify the thickness of the outline and/or fill the inside of the shape. However both features are not implemented by the current version of the base class library.
Filling Shapes
DrawEllipse and DrawRectangle both have overloads that support specifying a gradient fill to colour in the internal area of the shape (the 7 parameters set to 0 in the above examples).
The specification of a gradient fill consists of a start and end co-ordinate and associated colours at those two points. The framework will then apply a linear gradient between those two points. Any point “before” the start co-ordinate will be the starting colour, while any point “after” the end point will be the end colour. If both the start and end colours are the same a solid fill will be obtained.
The co-ordinates for the gradient start and end points are measured in screen co-ordinates. I.e. they are relative to the top left corner of the LCD and could refer to locations outside the area of the shape being drawn. This fact can be used to produce some interesting rendering and animation effects.
The opacity parameter allows the fill to be semitransparent and show previous content drawn to the same region of the bitmap. The opacity is a byte value with 0 indicating fully transparent, and 255 indicating full opaque (solid fill).
The fill effect shown in the image above was achieved via the following code sample. Notice the direction of the linear fill (as dictated by it’s start and end co-ordinates), and the fact that the bottom right half of the rectangle is a solid white fill due to this region being “after” the gradient’s end point.
bmp.DrawRectangle(Color.White, // outline colour 0, // outline thickness (no outline) 50, // x 50, // y 100, // width 100, // height 0, // x corner radius 0, // y corner radius red, // start gradient colour 50, // start gradient x 50, // start gradient y Color.White, // end gradient colour 100, // end gradient x 100, // end gradient y 0xFF); // opacity of fill
Sample Applications
[Download drawingexample.zip - 8.6 KB]
The sample application available for download demonstrates a number of basic drawing operations as discussed above. The application cycles through a number of demonstrations. The sample application also demonstrates the use of System.Reflection functionality within the .NET Micro Framework to find the examples. If you would like to experiment with the drawing APIs, this sample application would be an ideal test harness, just add another “Example_XYZ” method that contains your drawing code and your example will be automatically picked up.
[Download randomshapes.zip - 35 KB]
Another sample application is available for download (without explanation as to how it is implemented). This example helps demonstrates the rendering capabilities of the .NET Micro Framework by creating and animating up to 50 random rectangles of different size, colour and alpha transparency over top of the .NET Micro Framework snowflake logo. It also demonstrates the fact that the .NET Micro Framework emulator is really a simulator. You will notice that running this example under the emulator produces very impressive rendering speeds which are not matched when running on actual hardware.
My next blog entry about the .NET Micro Framework will discuss how to create a basic WPF style application. Eventually I will outline an alternative approach for drawing basic shapes that enables the WPF framework to take care of compositing the individual shapes onto the screen, enabling basic shapes to be animated and moved around in a more object orientated manor. | http://www.christec.co.nz/blog/archives/175 | CC-MAIN-2019-30 | refinedweb | 1,447 | 54.73 |
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LightWallet
LightWallet is a open source lightweight J2ME personal finance management application for mobile phones.3.5 weekly downloads | https://sourceforge.net/directory/developmentstatus:production/os:independent/environment:handhelds/ | CC-MAIN-2016-50 | refinedweb | 682 | 50.36 |
Details
- Type:
Bug
- Status: Closed
- Priority:
Major
- Resolution: Fixed
- Affects Version/s: 0.6.0
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- Component/s: Query Processor, Serializers/Deserializers
- Labels:None
Description
With the following data in table input4_cb:
Key Value
------ --------
NULL 325
18 NULL
The following query:
select * from input4_cb a join input4_cb b on a.key = b.value;
returns the following result:
NULL 325 18 NULL
The correct result should be empty set.
When 'null' is replaced by '' it works.
Issue Links
- incorporates
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- is cloned as
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- is duplicated by
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- relates to
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Activity
By adding logs to ExecReducer, I see that the input to reduce is the following:
{"key":{"joinkey0":null},"value":{"_col0":null,"_col1":35},"alias":0} {"key":{"joinkey0":null},"value":{"_col0":12,"_col1":null},"alias":1} {"key":{"joinkey0":10},"value":{"_col0":10,"_col1":1000},"alias":0} {"key":{"joinkey0":10},"value":{"_col0":10,"_col1":100},"alias":0} {"key":{"joinkey0":12},"value":{"_col0":12,"_col1":null},"alias":0} {"key":{"joinkey0":35},"value":{"_col0":null,"_col1":35},"alias":1} {"key":{"joinkey0":100},"value":{"_col0":100,"_col1":100},"alias":0} {"key":{"joinkey0":100},"value":{"_col0":10,"_col1":100},"alias":1} {"key":{"joinkey0":100},"value":{"_col0":100,"_col1":100},"alias":1} {"key":{"joinkey0":1000},"value":{"_col0":10,"_col1":1000},"alias":1}
And joinkey with null values are processed under same group, I think they should be processed in different groups, because comparison between nulls is not defined.
I'm not actively working on it. Please feel free to take it.
The joins are implemented in the JoinOperator and CommonJoinOperators for regular reduce-side joins. The map-side joins are implemented in the MapJoinOperator.
In the reduce side joins, the join keys are treated as distribution keys from the mappers to the reducers so that each group (marked by beginGroup() and endGroup()) will consists of rows with the same join keys. The reduce-side joins will cache all rows within a group except the last one (aka streaming table), which is scanned and cartesian producted with the cached rows of the other tables. I think the fix would be to check the NULL value of the join keys and do proper output based on the semantics of different types of joins.
For the map-side join, it's basically a hash join where the small table is read in entirety in a hash table and probed while scanning the streaming table.
There are other types of joins (bucketed map-side join, sort merge join etc.), but they all rely on the 3 classes mentioned above.
Let me know if you have further questions for you to get started.
Thanks for Ning and Amareshwari, we are looking forward to see the bug fixed. I think it's Okay to solve it by modifying the *JoinOperators, but it will be great if we can filter the NULL values in mappers, say, in ReduceSinkOperator, provided if we can know which part of the reduce sink key is from join (other than from group by, distinct, etc,.).
Thanks Ning for the details.
To summarize the implementation of join:
- In reduce-side join, rows with same join keys are grouped together; and in MapSide join, rows with same join keys are added the same entry in the hash table.
- CommonJoinOperator.checkAndGenObject: The rows with same join key are cartesian producted with each other(i.e. with rows of different aliases). If there are no rows in one table alias, the rows of other table alias are ignored (for inner join) or cartesian producted with nulls (outer joins).
The above implementation works fine except for null join keys ; Since these rows are grouped together/hashed to same entry, the current issue exists.
I think the fix would be to check the NULL value of the join keys and do proper output based on the semantics of different types of joins.
This would need special handling for each type of join (inner, left outer, right outer, full outer an etc.). So, I'm thinking the better solution is not group rows with null join keys together. Then the above join algorithm works correctly for all types of joins.
Currently they are grouped together because HiveKey.compare compares the bytes of the key (in case of reduce-side join) and MapJoinObjectKey.equals returns true if both keys are null (in case of map-side join). I'm trying to see if can come up with a solution which does not group rows with null join keys together. Please correct me if am wrong.
Sorry I'm mistakenly expressed my idea, I mean values with NULL join keys shall be filtered out in mappers.
I think values with NULL join keys shall be filtered out because NULL equals nothing, and Hive only support equal join.
Please correct me if I'm wrong.
@Ted: as Amareshwari mentioned, a left outer join preserves rows on the left side regardless of whether the ON clause evaluates true. So in that case (and similar cases for right/full outer join), we can't filter out the rows with null join keys.
@Amareshwar, currently we already distinguish different join types with different functions (take a look at CommonJoinOperator.joinObjects()). I look forward to seeing your proposal to avoid grouping null-keyed rows.
@Ted, I agree with Amareshwar and John that we cannot avoid rows (or the value part of the key-value pairs) with null as a key. However you have a point in that if we know the join operator does not involve outer join at all (we already have a flag noOuterJoin in JoinDesc), then we could avoid sending rows will null keys from the mappers to the reducers. This will save bandwidth as well as processing time. Could you open another JIRA and be able to submit a patch?
a left outer join preserves rows on the left side regardless of whether the ON clause evaluates true
That's right, thanks.
Attaching a simple patch which fixes JoinOperator (for reduce-side joins) and MapJoinOperator (for map-side joins) to not group the null join keys together.
Any comments on the approach/code are welcome.
Verified that SMBMapJoinOperator already filters nulls properly.
the change looks good to me. Can you also add one or few tests for sort merge join?
@Amareshwari, aside from adding new test cases for sort merge join, this patch also has some bugs.
For example in your test data:
hive> select * from myinput1 NULL 356 484 NULL 10 10 -- incorrect result below hive> select * FROM myinput1 a left outer JOIN myinput1 b ON a.value = b.value; 484 NULL 484 NULL 10 10 10 10 NULL 356 NULL NULL hive> select * FROM myinput1 a right outer JOIN myinput1 b ON a.value = b.value; 484 NULL 484 NULL 10 10 10 10 NULL NULL NULL 356 hive> select * FROM myinput1 a left outer JOIN myinput1 b right outer join myinput1 c ON a.value = b.value and b.value = c.value; NULL NULL NULL NULL 484 NULL NULL NULL NULL NULL 10 10 NULL NULL NULL NULL NULL 356
Can you take a look? I'm not sure whether ending a group and starting a new group for each null-keyed row works for all cases particularly in joins involving more than 2 tables and mixture of left and right outer joins.
Thanks Ning for your comments.
select * FROM myinput1 a left outer JOIN myinput1 b ON a.value = b.value;
select * FROM myinput1 a right outer JOIN myinput1 b ON a.value = b.value;
This is happening because I'm assuming nr.get(0) in JoinOperator is the join-key. It seems it not always true that key is the first element in the ArrayList. When I modified a the code to the following, above queries are giving correct results.
StructObjectInspector soi = (StructObjectInspector) inputObjInspectors[tag]; StructField sf = soi.getStructFieldRef(Utilities.ReduceField.KEY .toString()); Object keyObject = soi.getStructFieldData(row, sf); if (SerDeUtils.isNullObject(keyObject, soi)) { endGroup(); startGroup(); }
Added method SerDeUtils.isNullObject(keyObject, soi) to know if the object passed is representing a NULL object.
select * FROM myinput1 a left outer JOIN myinput1 b right outer join myinput1 c ON a.value = b.value and b.value = c.value;
Looking at Stage-1 of "explain" for the above query:
Stage: Stage-1 Map Reduce Alias -> Map Operator Tree: a TableScan alias: a Reduce Output Operator sort order: tag: 0 value expressions: expr: key type: int expr: value type: int b TableScan alias: b Reduce Output Operator sort order: tag: 1 value expressions: expr: key type: int expr: value type: int Reduce Operator Tree: Join Operator condition map: Left Outer Join0 to 1 condition expressions: 0 {VALUE._col0} {VALUE._col1} 1 {VALUE._col0} {VALUE._col1} handleSkewJoin: false outputColumnNames: _col0, _col1, _col4, _col5 Filter Operator predicate: expr: (_col1 = _col5) type: boolean File Output Operator compressed: false GlobalTableId: 0 table: input format: org.apache.hadoop.mapred.SequenceFileInputFormat output format: org.apache.hadoop.hive.ql.io.HiveSequenceFileOutputFormat
Join happens without join key? Here, join output is the Cartesian product of a and b on which FilterOperator is applied, Am I right? I see the semantics of inner/outer join on two tables without join condition is to produce Cartesian product. As a side note: "MySql does not allow outer joins without join condition".
If Join is allowed without join condition to produce Cartesian product of the two tables, then my patch should be changed to consider if join-key is defined for the join or not. I could reproduce it by simple query "select * FROM myinput1 a JOIN myinput1 b". I think the same applies to MapJoin as well.
Verified that SMBMapJoinOperator already filters nulls properly.
Can you also add one or few tests for sort merge join?
It seems my verification was wrong here, I thought if the table is sorted and hive.optimize.bucketmapjoin, hive.optimize.bucketmapjoin.sortedmerge are set to true, MapJoin uses SMBMapJoinOperator. But it was using MapJoinOperator it self. When I created a table with "sorted by" column, I see it using SMBMapJoinOperator. Currently if there are any nulls in the input table, SMBJoin fails with NullPointerException:
Caused by: java.lang.NullPointerException at org.apache.hadoop.io.IntWritable.compareTo(IntWritable.java:60) at org.apache.hadoop.io.WritableComparator.compare(WritableComparator.java:115) at org.apache.hadoop.hive.ql.exec.SMBMapJoinOperator.compareKeys(SMBMapJoinOperator.java:389) at org.apache.hadoop.hive.ql.exec.SMBMapJoinOperator.processKey(SMBMapJoinOperator.java:438) at org.apache.hadoop.hive.ql.exec.SMBMapJoinOperator.processOp(SMBMapJoinOperator.java:205) at org.apache.hadoop.hive.ql.exec.Operator.process(Operator.java:458) at org.apache.hadoop.hive.ql.exec.Operator.forward(Operator.java:698) at org.apache.hadoop.hive.ql.exec.TableScanOperator.processOp(TableScanOperator.java:45) at org.apache.hadoop.hive.ql.exec.Operator.process(Operator.java:458) at org.apache.hadoop.hive.ql.exec.SMBMapJoinOperator.fetchOneRow(SMBMapJoinOperator.java:479) ... 17 more
Will look into this.
For inner, left and right outer joins, a simpler fix would be to add a filter on top.
Now, I agree it would be simpler
. Will consider this also and see if i can do some special handling for full outer joins.
@Amareshwari, sorry the syntax was wrong for the 3 table joins. Below is the correct syntax and plan.
explain select * from src a left outer join src b on (a.value=b.value) right outer join src c on (b.value=c.value); OK ABSTRACT SYNTAX TREE: (TOK_QUERY (TOK_FROM (TOK_RIGHTOUTERJOIN (TOK_LEFTOUTERJOIN (TOK_TABREF src a) (TOK_TABREF src b) (= (. (TOK_TABLE_OR_COL a) value) (. (TOK_TABLE_OR_COL b) value))) (TOK_TABREF src c) (= (. (TOK_TABLE_OR_COL b) value) (. (TOK_TABLE_OR_COL c) value)))) (TOK_INSERT (TOK_DESTINATION (TOK_DIR TOK_TMP_FILE)) (TOK_SELECT (TOK_SELEXPR TOK_ALLCOLREF)))) STAGE DEPENDENCIES: Stage-1 is a root stage Stage-0 is a root stage STAGE PLANS: Stage: Stage-1 Map Reduce Alias -> Map Operator Tree: a TableScan alias: a Reduce Output Operator key expressions: expr: value type: string sort order: + Map-reduce partition columns: expr: value type: string tag: 0 value expressions: expr: key type: string expr: value type: string b TableScan alias: b Reduce Output Operator key expressions: expr: value type: string sort order: + Map-reduce partition columns: expr: value type: string tag: 1 value expressions: expr: key type: string expr: value type: string c TableScan alias: c Reduce Output Operator key expressions: expr: value type: string sort order: + Map-reduce partition columns: expr: value type: string tag: 2 value expressions: expr: key type: string expr: value type: string Reduce Operator Tree: Join Operator condition map: Left Outer Join0 to 1 Right Outer Join1 to 2 condition expressions: 0 {VALUE._col0} {VALUE._col1} 1 {VALUE._col0} {VALUE._col1} 2 {VALUE._col0} {VALUE._col1} handleSkewJoin: false outputColumnNames: _col0, _col1, _col4, _col5, _col8, _col9 Select Operator expressions: expr: _col0 type: string expr: _col1 type: string expr: _col4 type: string expr: _col5 type: string expr: _col8 type: string expr: _col9 type: string outputColumnNames: _col0, _col1, _col2, _col3, _col4, _col5 File Output Operator compressed: true GlobalTableId: 0 table: input format: org.apache.hadoop.mapred.TextInputFormat output format: org.apache.hadoop.hive.ql.io.HiveIgnoreKeyTextOutputFormat Stage: Stage-0 Fetch Operator limit: -1
Attaching patch that fixes the bugs in earlier patch, that Ning has found. Also adds more testcases.
Can you also add one or few tests for sort merge join?
Attached file smbjoin_nulls.q.txt has tests for sort merge join. But it fails with NPE as mentioned as earlier. I tried to fix the NPE, but could not come up with a fix. Shall I do it on followup jira?
For inner, left and right outer joins, a simpler fix would be to add a filter on top.
I think this can be done as part of HIVE-1544 as an improvement.
@Amareshwari, sorry the syntax was wrong for the 3 table joins.
Ning, Hive was not complaining about the syntax. So, included this also in the testcase. The results are fine with the latest patch.
Submitting patch for the review of patch-741-1.txt
Patch fixes SMBMapJoinOperator also. I modified compareKeys(ArrayList<Object> k1, ArrayList<Object> k2) to do the following:
if (hasNullElements(k1) && hasNullElements(k2)) { return -1; // just return k1 is smaller than k2 } else if (hasNullElements(k1)) { return (0 - k2.size()); } else if (hasNullElements(k2)) { return k1.size(); } ... //the existing code.
Does the above make sense?
Updated the testcase with smb join queries.
When I'm running smb join on my local machine (pseudo distributed mode), I'm getting different results. I think that is mostly because of
HIVE-1561. Will update the issue with my findings.
All the tests passed with latest patch : patch-741-2.txt
Looks good in general. Some minor comments:
1) add more test cases for SMB joins. Currently the only test case has only 1 bucket which does not cover the most common use case. Can you add more test cases for more buckets? You can take a look at bucketed join queries included in the client positive tests.
2) SMBMapJoinOperator.compareKey() is called for each row so it is critical for performance. In your code the hasNullElement() could be called 4 times in the worse case. If you cache the result it can be called only twice.
Yongqiang, any further comments?
Thanks Ning for the comments.
Patch incorporates the review comments. Looked at smb_mapjoin* query files and updated smb join queries.
The SMB test case still has a minor issue: the tables was created as 2 buckets but there is only 1 file in the tables. This is conflicting to the table schema. If a table is defined as bucketd 2, there should be 2 files in the partition or table. They SMB join takes the 1st file in T1 join the 1st file in T2, and 2nd file in T1 join 2nd file in T2. So the test case should cover this use case.
Updated smb input with two files.
Looks good except one mintor thing: SerDeUtils.java:369 should return true? Amareshwari, can you upload a new patch and I'll run unit tests.
Yongqiang, can you test this patch on the production SMB join queries?
Updated the patch. Thanks Ning for your help.
+1. The patch looks good to me.
(Only have one minor comment on the name of "hasNullElements", should we rename it since this function is used to determine all keys are null?)
also about Ning's comments:
>>2) SMBMapJoinOperator.compareKey() is called for each row so it is critical for performance. In your code the hasNullElement() could be called 4 times in the worse case. If you cache the result it can be called only twice.
Agree. Not sure how much overhead is there, will try to estimate the overhead over production running. That will be great if you can try to cache the null check results, so that it can only happen one time for each key.
Amareshwari, aside from Yongqiang comment, join_null.q's result is not deterministic – the SMB joins result in different orders. Can you make it deterministic by adding a 'order by' clause at the end of the queries? I'll attach my test run results
uploading test results join_null.q.out which has conflicts with the patch-741-5.txt.
Patch with following changes:
- Renamed the method hasNullElements to hasAllNulls
- Added keyToHasNullsMap to SMBMapJoinOperator to cache whether key has nulls or not, which is populated when the key elements are computed.
- Added appropriate "order by" clauses to smb join queries in the testcase
+1. Will commit if tests pass.
Committed. Thanks Amareshwari!
I see the same result even if 'null' is replaced with ''.
To reproduce the above, I created a table input1 with
Loaded the following input using Load data command
I see the following output for join queries executed.
Expected output is obtained from mysql db for a similar query.
Ning, if you are not working on the fix for this, I would like to contribute. Would need your help understanding join code also, as I'm a new to hive. | https://issues.apache.org/jira/browse/HIVE-741?focusedCommentId=12896793&page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel | CC-MAIN-2015-11 | refinedweb | 2,979 | 57.06 |
Game development with Pygame
Welcome to the first tutorial of the series: Building games with Pygame. Games you create with Pygame can be run on any machine that supports Python, including Windows, Linux and Mac OS.
In this tutorial we will explain the fundamental of building a game with Pygame. We’ll start of with the basics and will teach you how to create the basic framework. In the next tutorials you will learn how to make certain types of games.
You may like
PyGame introduction
You’ll end up with a program similar to the one on the right:
A game always starts in an order similar to this (pseudo code):
The game starts with initialization. All graphics are loaded, sounds are loaded, levels are loaded and any data that needs to be loaded. The game continues running until it receives a quit event. In this game loop we update the game, get input and update the screen. Depending on the game the implementation widely varies, but this fundamental structure is common in all games.
In Pygame we define this as:
The Pygame program starts with the constructor init(). Once that is finished on_execute() is called. This method runs the game: it updates the events, updates the screen. Finally, the game is deinitialized using on_cleanup().
In the initialiasation phase we set the screen resolution and start the Pygame library:
We also load the image.
This does not draw the image to the screen, that occurs in on_render().
The blit method draws the image (image_surf) to the coordinate (x,y). In Pygame the coordinates start from (0,0) top left to (wind0wWidth, windowHeight). The method call pygame.display.flip() updates the screen.
Continue the next tutorial and learn how to add game logic and build games :-)
13 thoughts on “Game development with Pygame”
- June 13, 2015
First of all, nice job ! Started off with Python game programming myself, with the help of this tutorial. There is one thing I do not understand though.
def on_execute(self):
if self.on_init() == False:
self._running = False
on_init has no return value defined, how are you able to check on_init() for False?
Would appreciate an answer 🙂
- June 13, 2015
Hi Phil, thanks! At present that statement is not reachable. You could make on_init() return a value in case the game data loading fails. When calling pygame.init(), any errors will cause an exception. You can call pygame.display.get_init() which returns True if the display has been initialised.
- May 15, 2015
I was on the python beginner tutorials and somehow ended up here after the polymorphism stuff. There’s too much new stuff here that I don’t think I’m ready for. Where do I go from polymorphism?
- May 15, 2015
On which concepts would you like more tutorials? I’ll write them if you let me know. You could try the network tutorials or the Tk (gui) tutorials that I’ll upload in a second.
- May 18, 2015
I want to learn any concepts that will be useful in getting me an entry level job without a bachelor’s degree.
- May 18, 2015
Hi Jordan, I’ll add more tutorials which will be helpful in achieving your goal 🙂
- October 29, 2015
Hi Frank!
, i need to make a dynamic GUI on python. It is for simulating a horizon indicator in which the horizon plane translates and rotates showing roll and pitch. i have made a static GUI in PYQT using different Widgets and now i am stuck. can you please guide how can i show pich and roll movements.
- October 31, 2015
Sure, could you post your code?
- May 14, 2015
Thanks! Making games is something I always wanted t
a whack at, Python/PyGame may just bring that within reach
- May 14, 2015
Glad to help! Do you wish to know about any specific type of game?
- May 24, 2015
A jump-n-run in the line of Bruce Lee – C64 style 🙂
- May 24, 2015
Added a short tutorial on jump-n-run logic.
- May 29, 2015
Thankzzzzz 🙂 | https://pythonspot.com/game-development-with-pygame/ | CC-MAIN-2019-22 | refinedweb | 677 | 75.4 |
Rails 6: Action Text
Introduction
Rails 6 is now out and can be used by the public. In a previous post, I took a look at Active Storage; a new framework bundled with Rails 5.2. The framework highlighted today comes fresh out of the Rails 6: Action Text. We'll be going over what Action Text is and how to set it up.
As I previously mentioned, we'll be using Active Storage through the process of using Action Text, so make sure you have it all set up and ready to go. If you don't want to implement it in your own project and want to get the end result, you can find that at the project's repository.
What is Action Text?
Action Text is a new Rich Text editing framework created and designed to get around browser inconsistent WYSIWYG HTML editors; requiring additional plugins to be used or JavaScript hacks to be implemented to get it working across all major browsers and devices.
Behind the scenes, Action Text is powered by a newer and more powerful Rich Text editor: Trix. Visit Trix's homepage to find out more information and how it's different than other rich text editors. Trix's claim is that it allows users to compose beautifully formatted text in their web applications. Trix comes to us from the creators of Rails, Basecamp.
Bonus
I'll be walking through how to remove the image both from the Trix editor and the server it's uploaded to as well as manipulate the image blob information in the bonus content below!
Setup
This app is very basic, which makes upgrading from Rails 5 to 6 very easy as it doesn't have any dependencies that don't already work with Rails 6. If you aren't using that project, please consult the official Rails guides for more information on upgrading a more sophisticated app to Rails 6. The only prerequisite, if you wish to follow along, is to have Active Storage already set up and working.
If you were following along with the previous post, there is a new controller added to the project. Please run
rails g controller Attachments destroyin the console to generate that file or check the repository.
Moving right along, we will need Rails 6. To upgrade to Rails 6 as well as getting Trix to work, you will need to update the
gem 'rails' line as well as adding the Trix gem in your
Gemfile.rb file then run
bundle install in your console.
# Gemfile.rb # Add trix, Replace "gem 'rails', '~> 5.x.x'`": gem 'rails', github: 'rails/rails' gem 'trix'
The routes of the application are as follows:
# config/routes.rb Rails.application.routes.draw do root 'posts#index' match 'blobs/:signed_id/*filename', to: 'blobs#show', via: [:get, :post] delete 'attachments/:signed_id/*filename', to: 'attachments#destroy' resources :attachments, only: [:destroy], as: :destroy_attachment resources :posts end
After all of the dependencies have been installed by bundler, we'll need to install Action Text. To do this, run the following command in the console:
rails action_text:install
Note: The installer uses Yarn to download the dependencies so make sure you have Yarn installed and added to your PATH.
We will also need to make sure that we have the JavaScript set up for Trix. To do this, add this to your
app/assets/javascripts/application.js file before
//= require_tree .:
// app/assets/javascripts/application.js //= require rails-ujs //= require activestorage //= require turbolinks //= require trix //= require_tree .
You'll also notice that a new migration was generated for you which creates a table called action_text_rich_texts. This table stores the rich text information from Trix as sanitized HTML. As with the Active Storage migrations, it contains a column called
record, which is a polymorphic association. As was explained in the last post, this is important so that it can be used with any model in your app without tying the association down to a single or a limited amount of models.
Point of Interest: It is very helpful that Rails sanitizes the Trix content for you so you don't have to explicitly do it yourself. If that wasn't properly handled, you could open your app up to possible Cross-site Scripting (XSS) Attacks if someone would submit a
<script src="></script> onto one of your views, for example.
Make sure that you run
rails db:migrate to update your database with the new Action Text tables. That's enough for the setup, let's see how to use this new feature.
Implementation
Continuing from the previous project, we will need to tell Rails that we wish to use Trix with our Post model. Our Post model should look like this:
# app/models/post.rb class Post < ApplicationRecord has_rich_text :content has_one_attached :main_image has_many_attached :other_images def attach_other_images(signed_blob_id) blob = ActiveStorage::Blob.find_signed(signed_blob_id) return other_images.attach(signed_blob_id) unless blob.present? other_images.attach(blob.signed_id) unless other_images.attachments.map(&:blob_id).include?(blob.id) end end
The
has_rich_text method from Action Text associates the rich text content from Trix onto this model by via the
content property.
We will need to tell Rails that we expect the
content property to be coming in from a form so we need to update the
post_params method in the PostsController file:
# app/controllers/posts_controller.rb ... def post_params params.require(:post).permit(:title, :body, :posted_at, :content, :main_image, other_images: []) end ...
As a refresher, we already are using Active Storage to upload photos to our Photo model:
<!-- app/views/posts/_form.html.erb --> <div class="field"> <%= form.label :main_image %> <%= form.file_field :main_image %> </div> <% if post.main_image.attached? %> <p> <%= link_to 'Remove Main Image', "#{destroy_attachment_path(post.main_image.id)}?post_id=#{post.id}", method: 'delete', data: { confirm: 'Delete the main image attachment?' } %> </p> <div>Current main image: </div> <%= image_tag post.main_image.variant(resize: '200x200') %> <%= tag.input type: 'hidden', name: 'post[main_image]', value: post.main_image.blob.signed_id %> <% end %>
If you're NOT following along from the previous blog post, ignore this note. You'll notice that I removed the
:remove_main_imageattribute from the
Postmodel. This was replaced in favor of a better way of removing that image, which we'll go over below.
What this allows us to do is remove the main image from the post when the box is checked upon saving the form, if we so desire to do so.
Below that, add the following code for the Trix content editor:
<!-- app/views/posts/_form.html.erb --> <div class="field"> <%= form.label :content %> <%= form.rich_text_area :content %> </div>
The editor allows for dragging and dropping of files into the content box which makes it easy to attach images inside the editor in real-time!
After starting up your Rails server, if you haven't done that already, and navigating to, you should see the Trix text editor:
Note: If you get a Rails error that states
couldn't find file 'trix/dist/trix' with type 'text/css' then make the following adjustments to your
app/assets/stylesheets/actiontext.scss file:
// app/assets/stylesheets/actiontext.scss // Original configuration //= require trix/dist/trix // New Configuration //= require trix
Upon saving the form, you'll notice that it STILL doesn't work, what gives?
We need to tell Trix how to behave in our project with a little bit of customization via JavaScript. Including the code directly into this post would make the post longer than I would like so you can find the code for that on my github account for this project. The comments throughout the file explains how that code works. Feel free to open any issues or comment on any code in GitHub with any feedback you may have.
Now when you save the form, you'll see your rich text content on the page exactly how you wrote it in the editor, super slick!
Trix will save the image as the same size that you uploaded it. Basecamp is very explicit that Trix is not made to modify images in any way but to display them as they are. I like to have control over the content that I put on websites and how they look. Let's setup the controller action that is called from the aforementioned JavaScript file:
class BlobsController < ActiveStorage::BlobsController def show return super unless @blob.image? redirect_to @blob.variant(resize: '250x250').processed.service_url(disposition: params[:disposition]) end end
I want to take a little time to break down what is going on here. Although the controller action is pretty straight forward, there is a little bit of background knowledge to understand as well. Yay Rails! 🎉
Behind the scenes, ActionText is using the MiniMagick gem to do image processing. Although the ActionText methods abstract away direct interaction with the MiniMagick gem, it's still useful to know how the gem works.
To start with a very important note about this snippet: we are not inheriting from ApplicationController like in most other cases. To be able to access varaibles like
@blob during the HTTP GET action, we need to inherit from
ActiveStorage::BlobsController so that we can interject our own logic into this action or skip the modification if the blob isn't an image. In the latter case, we just call the method from the super class:
ActiveStorage::BlobsController
In the
show method, we can see by using the
@blob.variant method, we get the data coming through the GET XHR request. What this allows us to do is resize any image on the fly but that is not enough to persist those changes to that file which is why we chain the
.processed.service_url method which then gives it a place to be stored on disk. I've arbitrarily chosen the
250x250 dimensions for all images for simplicity.
If you recall the
routes.rb file above, you will notice that this line hits the
BlobsController#show action:
# config/routes.rb match 'blobs/:signed_id/*filename', to: 'blobs#show', via: [:get, :post]
Another side note but equally important to know: when modifying the
@blob directly via the
.variant method, Rails will check if this image is already cached in your system so that it will NOT create a new variant blob for the same image over and over again. In your Rails logs, you will see a line like this if the image is cached or not:
Disk Storage (0.1ms) Checked if file exists at key: variants/0015bpmf9n6d78dzcn0eiot5ttrn/a9c43bd9b22f280abc66c247e0d1de3fe8d49b2600367a9c8b3750dd0fc2645e (yes)
But what if we want to remove an image from the editor? How would we do that?
Note: Taking this approach won't remove it from the server and the file will still be stored on disk. This will just remove it from the post's
:content property.
We need to add a little bit of JavaScript to remove the image from the editor via an event listener that Trix exposes. This snippet of code comes directly from the JavaScript file I mentioned a little earlier in the post:
// app/assets/javascripts/trix-upload.js#L195 attachment.releaseFile();
Trix makes it easy to interact and manipulate data inside the editor. As long as we have a reference to an attachment, we just need to release the file from the editor. After doing this and saving the
Post to the database, it will no longer be included in the data of the
:content property.
Conclusion
What did we learn? We learned that Rails 6 is an AWESOME update to the framework that allows us to write beautifully formatted, rich text content for our websites which, with a little customization, can even upload images without using any 3rd party gems! We learned how to configure the routes, views, and controllers, with a helpful JavaScript file thrown in, so that we can upload and remove files directly from the editor.
I believe that which Rails 6 is poising to bring to the Rails family of frameworks is very exciting and I can't wait to dive more into its newer features.
Bonus Content
YOU MADE IT! I really appreciate you sticking through this post as I know it was a LOT of content and longer than I originally planned. We'll look at how to remove the image blob from the server while we are removing it from the Trix editor.
We will be adding a whole new controller:
AttachmentsController! To generate the controller, we'll run
rails g controller Attachments destroy on the console. I won't be showing all of the code on this post as that would be a little much. The code isn't complicated and you can find the full, commented version on the repository.
Essentially, we are calling that code through an
HTTP
DELETE request from JavaScript to purge it. You can find the definition and use-case recommendations of the
ActiveStorage::Blob#purge method on the Rails api documentation website.
After hitting this route, the logs will reflect that we did indeed delete the resource and any variants of it from the server:
Disk Storage (2.4ms) Deleted file from key: 0015bpmf9n6d78dzcn0eiot5ttrn Disk Storage (1.3ms) Deleted files by key prefix: variants/0015bpmf9n6d78dzcn0eiot5ttrn/
To point out the route for this in the
routes.rb file:
# config/routes.rb resources :attachments, only: [:destroy], as: :destroy_attachment
Bonus bonus
How did I know which controller to inherit from so that I could manipulate the blob information?
A little bit of research reasearch, reading the source code *cough* *cough*, and knowing a little bit of Rails background knowledge can help you find answers to many questions like these. In this particular case, I found what the definition that Rails defines as a route, which we can find with the
rails routes cli command, to upload a file:
rails_service_blob GET /rails/active_storage/blobs/:signed_id/*filename(.:format) active_storage/blobs#show
I'll break it down:
rails_service_blobis the name used by any route helpers in Rails. For our purposes, you can ignore this.
GETtells me that this controller action can only be handled with an HTTP GET request. This is why we didn't use a POST request when sending the XHR request from JavaScript.
/rails/active_storage/tells there is an internal namesapce called
ActiveStorage.
/blobs/tells me that on the
ActiveStoragenamespace, there is a
BlobsControllercontroller class.
/:signed_id/*filenameshows me how Rails handles this and what is required to be passed through the URL so I just copied this part verbatim into my own route definition.
active_storage/blobs#showtells me that the
ActiveStorage::BlobsControllerclass has a
showmethod that I can override. | https://bendyworks.com/blog/rails-6-action-text/index | CC-MAIN-2021-31 | refinedweb | 2,407 | 62.58 |
.
Example 1: Function to add 3 numbers.
Lets see what happens when we pass more than 3 arguments in the
adder() function.
def adder(x,y,z): print("sum:",x+y+z) adder(5,10,15,20,25)
When we run the above program, the output will be
TypeError: adder() takes 3 positional arguments but 5 were given
In the above program, we passed 5 arguments to the
adder() function instead of 3 arguments due to which we got
TypeError.
Introduction to *args and **kwargs in Python
In Python, we can pass a variable number of arguments to a function using special symbols. There are two special symbols:
- *args (Non Keyword Arguments)
- **kwargs (Keyword Arguments)
We use *args and **kwargs as an argument when we are unsure about the number of arguments to pass in the functions.
Python *args
*.
Example 2: Using *args to pass the variable length arguments to the function
def adder(*num): sum = 0 for n in num: sum = sum + n print("Sum:",sum) adder(3,5) adder(4,5,6,7) adder(1,2,3,5,6)
When we run the above program, the output will be **kwargs
**.
Example 3: Using **kwargs to pass the variable keyword arguments to the function)
When we run the above program, the output will be
Data type of argument: <class 'dict'> Firstname is Sita Lastname is Sharma Age is 22 Phone is 1234567890 Data type of argument: <class 'dict'> Firstname is John Lastname is Wood Email is [email protected].
Things to Remember:
- *args and *kwargs are special keyword which allows function to take variable length argument.
- *args passes variable number of non-keyworded arguments list and on which operation of the list can be performed.
- **kwargs passes variable number of keyword arguments dictionary to function on which operation of a dictionary can be performed.
- *args and **kwargs make the function flexible. | https://www.programiz.com/python-programming/args-and-kwargs | CC-MAIN-2021-04 | refinedweb | 312 | 53.85 |
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SCHOTEL, BAS 2018. Legal Protection as Competition for Jurisdiction: The Case of Refugee Protection through Law in the Past and at Present. Leiden Journal of International Law, Vol. 31, Issue. 01, p. 9.
KIM, SEUNGHWAN 2017. Non-Refoulement and Extraterritorial Jurisdiction: State Sovereignty and Migration Controls at Sea in the European Context. Leiden Journal of International Law, Vol. 30, Issue. 01, p. 49.
De Boer, T. 2015. Closing Legal Black Holes: The Role of Extraterritorial Jurisdiction in Refugee Rights Protection. Journal of Refugee Studies, Vol. 28, Issue. 1, p. 118.
TREVISANUT, SELINE 2014. The Principle of Non-Refoulement And the De-Territorialization of Border Control at Sea. Leiden Journal of International Law, Vol. 27, Issue. 03, p. 661.
On 23 February 2012, the European Court of Human Rights (the Court), sitting as a Grand Chamber, delivered its long-anticipated judgment in the Hirsi Jamaa and Others v Italy (Hirsi) case.1.2
1 App no 27765/09.
2 At present, two applicants have died: Abbirahman Hasan Shariff in the attempt to return to Europe by sea; and Mohamed Mohmed Abuker who passed away in Libya from natural cause.
3 Protocol and Additional Protocol on the cooperation in the fight against irregular immigration of 29 December 2007; Executive Protocol of 4 February 2009, supplementary to the one signed on 29 December 2007. For an analysis of the agreements of technical and police cooperation between Italy and Libya, see, M Giuffré, ‘State Responsibility beyond Borders: What Legal Basis for Italy's Push-backs to Libya?’ IJRL (forthcoming 2012).
4 European Convention for the Protection of Human Rights and Fundamental Freedoms of 4 November 1950.
5 Protocol 4 to the ECHR of 16 September 1963.
9 On the relation between illegal migrants and asylum seekers in readmission and return policies, see J van der Klaauw, ‘Irregular Immigration and Asylum-Seeking: Forced Marriage or Reason for Divorce?’ in B Bogusz, R Cholewinski, A Cygan, and E Szyszczak (eds), Irregular Migration and Human Rights: Theoretical, European, and International Perspectives (Martinus Nijhoff 2004).
10 The Court also added that the applicants were directly put on board Italian ships, which are considered to be Italian territory under art 4 of the Italian Code of Navigation.
11 M den Heijer, ‘Europe Beyond its Borders: Refugee and Human Rights Protection in Extraterritorial Immigration Control’ in B Ryan and V Mitsilegas (eds), Extraterritorial Immigration Control: Legal Challenges (Martinus Nijhoff 2010) 190.
12 B Ryan, ‘Extraterritorial Migration Control: What Role for Legal Guarantees?’ in ibid 37.
13 All countries in Europe are party to the 1951 Refugee Convention, with Turkey maintaining a geographical reservation: Convention relating to the Status of Refugees 28 July 1951 (Refugee Convention).
14 The ECtHR's approach in Bankovic and Others v Belgium and Others (2007) 44 EHRR SE5, 86 (Bankovic) now has to be read subject to its judgment in Al-Skeini and Others v UK App no 55721/07 (ECtHR, 7 July 2011).
15 Milanovic M, The Extraterritorial Application of Human Rights Treaties (OUP 2011) 8.
16 In accordance with the UNHCR's proposed definition, ‘interception’ embraces all those extraterritorial activities carried out by a State to keep undocumented migrants further away from their territory, thus preventing entry by land, sea, or air. See, UNHCR Executive Committee, ‘Interception of Asylum Seekers and Refugees: the International Framework and Recommendations for a Comprehensive Approach’ EC/50/SC/CPR.17 (9 June 2000) para 10.
17 GS Goodwin-Gill, ‘The Extraterritorial Reach of Human Rights Obligations: A Brief Perspective on the Link to Jurisdiction’ in L Boisson de Chazournes and M C Kohen (eds), International Law and the Quest for its Implementation/Le Droit International et la Quête de sa Mise en Oeuvre: Liber Amicorum Vera Gowlland-Debbas (Brill 2010) 306.
18 For an extended critical analysis of the Bankovic case, see, R Lawson, ‘Life after Bankovic—On the Extraterritorial Application of the European Convention on Human Rights’ in F Coomans and M T Kamminga (eds), Extraterritorial Application of Human Rights Treaties (Intersentia 2004) 104; K Wouters, International Legal Standards for the Protection from Refoulement (Intersentia 2009) 205–6.
19 The first three categories of exceptions were first set out by the ECtHR in Loizidou v Turkey (preliminary objections) (1995) 20 EHRR 99, para 62.
21 Bankovic (n 14) para 70. See also, Cyprus v Turkey (1982) 4 EHRR 482 (Commission Decision) para 8.
22 Bankovic (n 14) para 73. In this regard, the Court in Hirsi also cites the Al-Saadoon and Mufdhi v United Kingdom (2010) 51 EHRR 9, para 85.
28 Hirsi (n 1) para 73. The Court refers here to Al-Skeini (n 14) paras 132 and 136; and to Medvedyev and Others v France (2010) 51 EHRR 39, para 67 (Medvedyev). For an analysis of the Al-Skeini case, see C Mallory, ‘European Court of Human Rights Al-Skeini and Others v United Kingdom (App no 55721/07) Judgment of 7 July 2011’ (2012) 61 ICLQ 301.
32 ibid para 81. See, Papastavridis E, ‘European Court of Human Rights Medvedyev et al v France’ (2010) 59 ICLQ 867–82.
38 ibid para 114. The Court cites Soering v UK (1989) 11 EHRR 439, paras 90–1; Vilvarajah and Others v the United Kingdom (1991) 14 EHRR 248, para 103; Jabari v Turkey App no 40035/98 (ECtHR, 1 July 2000), para 38; Ahmed v Austria (1997) 24 EHRR 278, para 39; HLR v France (1997) 26 EHRR 29, para 34; and Salah Sheekh v The Netherlands (2007) 45 EHRR 50, para 135.
39 Under art 33(1) of the Refugee Convention, ‘No Contracting State shall expel or return (“refouler”) a refugee in any manner whatsoever to the frontiers of territories where his life or freedom would be threatened on account of his race, religion, nationality, membership of a particular social group or political opinion.’
41 App no 39473/98, Admissibility Decision (ECtHR, 11 January 2001) (Xhavara).
42 See Weinzierl R and Lisson U, Border Management and Human Rights (German Institute for Human Rights 2007) 63, 70.
47 For example, the UN Human Rights Committee (HRC) recognizes the extraterritorial scope of the relevant Covenant to the non-refoulement obligation where individuals are either within or outside the territory of a State party, but in any case under the power or actual control of the State itself. This also implies a prohibition to return a person where reliable grounds exist to believe that he will suffer an irreparable harm either in the readmitting country or in any other country where he could subsequently be removed (HRC, General Comment 31, para 12). See also, the HRC Concluding Observations on the United States (HRC, Concluding Observations on the United States of America, UN doc CCPR/C/USA/CO/3Rev. 1 (18 December 2006) para 16).
48 Under art 3(1) of the Convention against Torture (CAT), ‘No State Party shall expel, return (“refouler”) or extradite a person to another State where there are substantial grounds for believing that he would be in danger of being subjected to torture.’
49 CAT/C/41/D/323/2007 (21 November 2008).
52 According to the Presidium of the Convention that drafted the Charter, the Explanations ‘have no legal value and are simply intended to clarify the provisions of the Charter’.
53 Regulation of the European Parliament and of the Council (EC) 562/2006 15 March 2006 establishing a Community Code on the rules governing the movement of persons across borders [2006] OJ L105/1 (SBC).
55 SBC, paras 2.1.3. and 2.2.1, Annex VI. While at sea, controls can be performed ‘in the territory of a third country’ (para 3.1.1, Annex VI), checks can be carried out also ‘in [rail] stations in a third country where persons board the train’ (para 1.2.2, Annex VI). For an analysis of the scope of application of the SBC, see, den Heijer (n 11) 176–80.
56 Letter from ex-Commissioner Barrot to the President of the LIBE Committee 15 July 2009, as cited by the ECtHR in Hirsi (n 1) paras 34, 135.
57 ibid. See also, Moreno-Lax V, ‘Seeking Asylum in the Mediterranean: Against a Fragmentary Reading of EU Member States’ Obligations Accruing at Sea’ (2011) 23 IJRL 174; Nascimbene B, ‘Il Respingimento degli Immigrati e i Rapporti tra Italia e Unione Europea’ (2009) Affari Internazionali 4.
60 See Conka v Belgium (2002) 34 EHRR 54, para 59 (Conka); Alibaks and Others v The Netherlands App no 14209/88, DR 59/274.
61 van Dijk P and van Hoof GJH, Theory and Practice of the European Convention on Human Rights (Kluwer 1984) 500.
62 In the Pranjko v Sweden case (App no 45925/99 (ECtHR, 23 February 1999)), the Court stated the fact that a number of aliens receive similar decisions does not lead to the conclusion that there is a collective expulsion when each person concerned has been given the opportunity to present arguments against his expulsion to the competent authorities on an individual basis. See Howley JD, ‘Unlocking the Fortress: Protocol No 11 and the Birth of Collective Expulsion Jurisprudence in the Council of Europe System’ (2006–07) 21 GILJ 117.
65 Hirsi (n 1) para 177. See also, B Ryan, ‘Hirsi: Upholding the Human Rights of Migrants at Sea’ (6 March 2012) Note for ILPA and the Migration and Law Network 5.
67 ibid para 175. To support this argument, the Court cites Marckx v Belgium (1979) 2 EHRR 330, para 41; Airey v Ireland (1979) 2 EHRR 305; Mamatkulov and Askarov v Turkey (2005) 41 EHRR 494, para 121; and Leyla Sahin v Turkey App no 44774/98 (ECtHR, 29 June 2004), para 136.
71 Under art 13 of the ECHR, ‘Everyone whose rights and freedoms as set forth in this Convention are violated shall have an effective remedy before a national authority notwithstanding that the violation has been committed by persons acting in an official capacity.’
72 Fischer-Lescano A, Löhr T and Tohidipur T, ‘Border Controls at Sea: Requirements under International Human Rights and Refugee Law’ (2009) 21 IJRL 286. The authors make the same claim with regard to art 33(1) of the Refugee Convention, which has been argued to contain an implicit right to an effective remedy. See also, Noll G, ‘Visions of the Exceptional: Legal and Theoretical Issues Raised by Transit Processing Centres and Protection Zones’ (2003) 5 EJML 332; Hathaway J, The Rights of Refugees under International Law (CUP 2005) 279; Edwards A, ‘Tampering with Refugee Protection: The Case of Australia’ (2003) 15(2) IJRL 210; Weinzierl and Lisson (n 48) 50.
73 App no 30471/08 (ECtHR, 22 September 2009), paras 111–14 (Abdolkhani).
80 Bahaddar v The Netherlands (1998) 26 EHRR 278, para 45.
81 See ECtHR, Shamayev and Others v Georgia and Russia App no. 36378/02 (ECtHR, 12 April 2005), para 460 (Shamayev); Garabayev v Russia (2009) 49 EHRR 12, para 106; Baysakov and Others v Ukraine App no 54131/08 (ECtHR, 18 February 2010), paras 71, 74–5; Muminov v Russia App no 42502/06 (ECtHR, 11 December 2008), para 101.
83 Gebremedhin v France App no. 25389/05 (ECtHR, 26 April 2007), para 66; Abdolkhani (n 73) para 58.
84 SH Legomsky, ‘Secondary Refugee Movements and the Return of Asylum Seekers to Third Countries: The Meaning of Effective Protection’ (UNHCR Report 2003) 88 < > accessed 31 March 2012.
86 Hussun and Others v Italy App nos 10171/05, 10601/05, 11593/05 and 17165/05 (ECtHR, 19 January 2010).
88 T.I. v The United Kingdom App no 43844/98 Admissibility Decision (ECtHR, 7 March 2000) 14. The reasoning of the Court implies a duty to examine the substance of an asylum application before expelling a person to an intermediary country if the situation in the country of origin ‘gives rise to concerns’. See Guild E, ‘The Europeanisation of Europe's Asylum Policy’ (2006) 18 IJRL 649.
90 According to the Court, since no national authority examined their allegation of a risk of ill-treatment if returned to Iran or Iraq, the applicants were not afforded an effective remedy in relation to their complaints under art 3. Abdolkhani (n 73) paras 113, 115.
91 Z.N.S. v Turkey App no 21896/08 (ECtHR, 19 January 2010), paras 47–9. Further cases remain pending on the issue of access to asylum determination procedures. See eg Sharifi and others v Italy and Greece, App no 16643/09, communicated 13 July 2009 (pending). For an extended analysis of the right to asylum in relation to the ECHR, see, Mole N and Meredith C, Asylum and the European Convention of Human Rights (Council of Europe Publishing 2010) 103–7.
92 Amuur v France (1996) 22 EHRR 533, para 43.
94 Of the same opinion, also J Schneider, ‘Comment to Hirsi (part II): Another Side to the Judgment’ (Strasbourg Observers, 5 March 2012) <> accessed 31 March 2012.
96 See, International Law Association, ‘Resolution 6/2002 on Refugee Procedures (Declaration on International Minimum Standards for Refugee Protection)’ (2002) para 8. See also, Inter-American Commission on Human Rights, Haitian Centre for Human Rights et al. v US, Case 10.675, para 163.
97 T Spijkerboer, ‘Stretching the Limits: European Maritime Border Control Policies and International Law’ in M-C Foblets (ed) The External Dimension of the Immigration and Asylum Policy of the European Union (Bruylant 2009) 13.
98 Spijkerboer T, ‘The Human Costs of Border Control’ (2007) 9 EJML 138.
99 Osman v UK (2000) 29 EHRR 245, para 116.
100 Response of the Italian Government to the Committee on the Prevention of Torture (CPT) Report, Appendix I, para d <> accessed 31 March 2012.
104 Guidelines on the treatment of persons rescued at sea of the International Maritime Organization (IMO), Resolution MSC.167(78), 20 May 2004, para 6.17 subsequently endorsed by the UN General Assembly in UN doc. A/RES/61/222, 16 March 2007.
110 This position finds ample support under international human rights and refugee law. See eg UNHCR, ‘Handbook on Procedures and Criteria for Determining Refugee Status’ HCR/1P/4/ENG/REV. 3 (December 2011) para 192. According to Goodwin-Gill, intercepted people should always be given an opportunity to set out reasons why they might be at risk if returned. See Goodwin-Gill GS, ‘The Right to Seek Asylum: Interception at Sea and the Principle of Non-refoulement’ (2011) 23 IJRL 449.
111 While art 1A(2) of the Refugee Convention only provides five grounds of persecution (‘race, religion, nationality, membership of a particular social group or political opinion’) to attract the protection of the Convention, no similar qualification applies to art 3 of the ECHR. For a review of case law, see Mole and Meredith (n 91) 25–6.
114 Following the same logic, the UNHCR declares that ‘claims for international protection made by intercepted persons are in principle to be processed in procedures within the territory of the intercepting State’. See UNHCR Protection Policy Paper ‘Maritime Interception Operations and the Processing of International Protection Claims: Legal Standards and Policy Considerations with Respect to Extraterritorial Processing’ (November 2010) 2 <> accessed 31 March 2012.
115 Hirsi (n 1) Concurring Opinion 40. The non-refoulement obligation has an absolute value ‘when’. See Hirsi (n 1) Concurring Opinion 41.
116 Under art 33(2) of the Refugee Convention, the principle of non-refoulement ‘may not […] be claimed by a refugee whom there are reasonable grounds for regarding as a danger to the security of the country in which he is, or who, having been convicted by a final judgment of a particularly serious crime, constitutes a danger to the community of that country’.
118 Edwards A, ‘Human Security and the Rights of Refugees: Transcending Territorial and Disciplinary Borders’ (2009) 30 MJIL 795.
121 Ibid 45. See also, the Parliamentary Assembly of the Council of Europe, ‘Resolution 1821 (2011) on the Interception and Rescue at Sea of Asylum Seekers, Refugees, and Irregular Migrants’, paras 9.3–9.6.
122 UNHCR, ‘Haitian Interdiction Case’, Brief Amicus Curiae (1993) 92.
123 See eg Lambert H, ‘Protection against Refoulement from Europe: Human Rights Law Comes to the Rescue’ (1999) 48 ICLQ 515–44.
124 Amnesty International, ‘Italy: ‘‘Historic’’ European Court Judgment Upholds Migrants’ Rights’ (24 February 2012) <-‘historic’-european-court-judgment-upholds-migrants’-rights> accessed 31 March 2012.
125 Frontex is the European Agency for the Management of Operational Cooperation at the External Borders of the Member States of the European Union, established on 26 October 2004 by Council Regulation (EC) 2007/2004. It plays a regulatory and coordinating role between the EU border guards, although ‘the responsibility for the control and surveillance of the external border lies with the Member States’ (art 1(2)).
127 Lawson R, Globalization and Jurisdiction (Kluwer Law International 2004) 206.
The author wishes to express her gratitude to E Gill-Pedro for reading an earlier draft of this paper, and to Prof A Alí and Prof G Noll for their advice on many aspects of this research. She also would like to thank the reviewers for their constructive suggestions. Remaining errors are only mine. This publication is part of my research at Lund University, thanks to a Scholarship awarded by the Swedish Institute.. | https://www.cambridge.org/core/journals/international-and-comparative-law-quarterly/article/watered-down-rights-on-the-high-seas-hirsi-jamaa-and-others-v-italy-2012/1F85EBD59A8C0695AC6D37687B4517EF | CC-MAIN-2018-09 | refinedweb | 2,910 | 50.67 |
attachments: accessing attachment's message is very slow
Bug Description
[Problem]
Performance processing attachments when referencing the message object really slows things down
https:/
[Discussion]
I love launchpadlib and use it a LOT for helping me get my work done on X.org. X.org bugs are really all about file attachments - crash dumps, log files, config files, yada yada. Pretty much every launchpadlib script I write deals with attachments in some way.
However, if you want to get the name of the uploader of the attachment, or when it was uploaded, this causes scripts to run a LOT slower. For interactive scripts this can result in it taking over a minute to load the bug. Even for non-interactive scripts this delay really reduces their usefulness.
I would like to see launchpadlib provide better optimized access to these details.
Attached is a test script I've used to do some performance measurements when different data is requested on a bug's attachments.
\time -f "%E" ./test_
Results
======
0. Just titles: 5.18 sec
1. do_a: 12.58
2. do_message: 42.33
3. do_a + do_message: 51.38
4. do_fb: 11.68
5. do_a + do_fb: 17.95
6. do_a + do_fb + do_message: 1:14.90
7. do_content: 11.84
8. do_a + do_content: 24.87
9. do_a + do_fb + do_content: 25.59
10. do_a + do_fb + do_message + do_content: 1:08.76
As you can see, it's faster to get all the files content (including printing contents to the screen!) than to print only the owner/date_
Something feels wrong - I would expect the difference between #1 and #3 to be on the order of maybe 4 sec max, not 40 sec. In this example bug, there is only a single message on the bug, compared with like 20 attachments, so you would expect #3 to be faster than #8, not take twice as long.
Fixes we need to CP from devel
=======
revno: 11156 [merge]
committer: Launchpad Patch Queue Manager <email address hidden>
branch nick: launchpad
timestamp: Mon 2010-07-19 18:32:16 +0100
[r=lifeless]
changed to no longer materialise every message on a Bug before
returning the first one.
Out of curiosity, any progress on this? Anything I could do to help?
The problem is probably in Launchpad itself, so I've moved this bug to launchpad-
jtv just asked me about something like this: we are seeing many oopses caused by attempts to read attachments off big bugs (eg bug 88746).
From a Python shell you can fairly easily reproduce this with
lp.bugs[
which gives something like:
https:/
This oops is pretty pathetic because about 50ms all the actually necessary queries are done, then it spends the rest of its timeout doing completely unnecessary and painful other queries.
I would speculate that something in lazr's toDataStructure is interacting badly with storm.
https:/
self.path = "comments/%d" % list(bug.
You could do something like this:
def getIndexForMess
results = store.find(Message, Bug.message = Message.id, Bug.id = self.id)
return list(results.
(sketch)
Yeah, I had hoped to find someone at the epic to help me investigate this bug further. Unfortunately, what I was told is that no one really understands the launchpad librarian. I got deryck to help me study the oops report a bit but we didn't make much headway.
What I've been doing is as I've found bug reports that trigger this bug, to either close the bug report or make my script skip over it in its processing. But it feels like I'm just sweeping the problem under the carpet.
The fix on devel improves things so it sometimes works; leonard's work will make it much better by dropping half the work or so, but we still need to improve the underlying api behaviour.
In light of bug #618849 being fixed, I re-ran this script for case #6. Originally I'd measured a time of 1:18; the script now completes with a time of 0:49.29.
This is being run on the same hardware, with the same version of Ubuntu as the original test. The bug report under measurement in this test case (bug #259156 ) has received a few comments but no additional attachments. So while the testing conditions aren't exact, they're fairly close. The one problem is that the script is triggering a NoCanonicalUrl assertion in launchpad, so I can't be certain the measurements are good. If they are, this suggests a 35-40% improvement which would be quite notable.
Just to check, I reran all the different cases, and found all cases involving message data show a similar reduction in run time, whereas cases not involving message data did not see such improvements. Again, the script terminates with an assertion when do_message is enabled, so this performance "improvement" could just be measuring an early termination.
0. Just titles: 5.18 sec ... 4.05 sec
1. do_a: 12.58 ... 15.78
2. do_message: 42.33 ... 37.61
3. do_a + do_message: 51.38 ... 43.31
4. do_fb: 11.68 ... 13.69
5. do_a + do_fb: 17.95 ... 30.55
6. do_a + do_fb + do_message: 1:14.90 ... 59.17
7. do_content: 11.84 ... 11.55
8. do_a + do_content: 24.87 ... 25.30
9. do_a + do_fb + do_content: 25.59 ... 26.82
10. do_a + do_fb + do_message + do_content: 1:08.76 ... 58.82
We still have to pull all Messages out to calculate the message links;
fixing that would make this faster still.
Bryce, btw, your bug re-requests the message multiple times - each time you dereference it; you should fix that to avoid misrepresenting the overheads.
Bryce, could you tighten this up to something like:
'bug/messages/1234' takes 2seconds (or whatever it does).
As it stands, its not really actionable as a timeout; and the script is doing several different things. Using the httplib debug option you should be able to identify the slow urls.
We also need a separate bug for the noncanonicalurl thing.
[ 0.0000 (0.5742 sec)] title: BootDmesg.txt
[ 0.0030 (0.0029 sec)] ispatch: Unspecified
[ 0.0038 (0.0009 sec)] http_etag: "c0d7800dcaa8bd
[ 0.0046 (0.0008 sec)] a.url: https:/
[ 0.3257 (0.3211 sec)] subject: Re: [regression] Touchpad vertical scrolling stopped working
[ 0.8545 (0.5288 sec)] owner: Andres Monroy-Hernandez
[ 1.1253 (0.2708 sec)] created: 2009-08-31 17:16:02.
[ 3.0988 (1.9735 sec)] modified: Mon, 31 Aug 2009 17:16:02 GMT
[ 3.0988 (0.0001 sec)] fb.url: https:/
[ 3.0989 (0.0000 sec)] content-type: text/plain; charset="utf-8"
[ 3.0992 (0.0004 sec)] filename: BootDmesg.txt
[ 3.0993 (0.0001 sec)] isatty: False
[ 3.0993 (0.0000 sec)] len: 54019
[ 3.0993 (0.0000 sec)] mode: r
[ 3.0994 (0.0000 sec)] pos: 0
[ 3.0994 (0.0000 sec)] softspace: 0
[ 3.0994 (0.0000 sec)] content: 54019
[ 3.0994 (0.0000 sec)]
Opening the fb consumes the most time. Accessing the message consumes about a second (1/3rd total time).
You should be able to get url tracking from launchpad lib by exporting and HTTPLIB2 option - I forge the details. That will tell us the actual slow request, which is what we need.
For now, the goal on this bug is to get an analysis of root cause. We'll regroup after that. | https://bugs.launchpad.net/launchpad/+bug/424671 | CC-MAIN-2019-22 | refinedweb | 1,221 | 75.4 |
One:
- Use these steps to download and run the MsiInv tool to create a list of applications that Windows Installer thinks are installed on the computer
- Open the MsiInv output file, locate the product that you are interested in removing and copy the Product Code value to your clipboard. The Product Code will be a GUID with curly braces surrounding it. Make sure to copy the curly braces in addition to the GUID value
- Go to the Start menu, choose Run and type cmd
- From the cmd prompt, run msiexec /x {product_code} using the Product Code value from the MsiInv output and try to uninstall it using the standard MSI uninstall command line
- If the uninstall succeeds, you can stop here
- If the uninstall did not succeed, download the smartmsizap tool (if you are interested, you can read about the behind-the-scenes design for smartmsizap here) and extract it to c:\ on your computer
- From the cmd prompt, run c:\smartmsizap.exe /p {product_code} using the Product Code value from the MsiInv output″> Added more specific information about extracting and running smartmsizap.exe from c:\ because otherwise Windows may not know where to find the exe when running the command from a cmd prompt </update>
<update date=”4/1/2009″> Fixed broken link to smartmsizap tool. </update>
Thanks for this great post. It really helped.
I was about to format my disk after those headaches with CTP builds and release install when finally your article saved my day.
Thanks a lot
Thanks a lot.
I had to go till the 6th step using smartmsizap, inorder to uninstall the beta versions of SQL Server.
There was an error when I tried to uninstall SQL Server 2005 CTP using 4th step (msiexec /x {product_code}). A message which shows an error in machine configuration file and an error in XMLReader was poped while doing that. A part of the error is described as follows.
The setup has encountered an unexpected error in datastore. The action is SetInstancePorperty. The error is: Source File Name: datastorecachedpropertycollection.cpp .
……
There was an XmlRW error: failure loading xmlrw.dll
Thanks,
Promod.
I used a software called Uninstaller! 2006 ( ) to remove all the previous versions of .NET Framework. It removes all the registry entries and hence your system is completely cleaned.
I used the MSInv trying to remove Microsoft SQL 2005 CTP but it didn’t work. When I used the smartmsizap command, it worked!!! I was almost giving up when I found this article. Very good tips!!! Thank you very much!!!!
Great Aaron, thanks for quick reply. SmartZap worked for me.
And I’m really glad Microsoft support for Developers.
Last 2 days, I’ve started working with Netbeans as I everything is free there, but its bad practice to map the namespace with folders, ‘coz. I’m back now.
Thanks again.
-pv
PingBack from
Dear Aaron:
I’m having a lot of problems installing SQL 2005 RTM on my WinXP SP2 machine. I think it may be because of manually uninstalling SQL 2005 CTP and/or VS 2005 Beta 2.0, probably in the wrong order. The error I get in the detail log file SQLSetup0019_COMPUTERNAME_SQL.log is "Error 29528. The setup has encountered an unexpected error while Updating Installed Files. The error is: Fatal error during installation.".
I uninstalled both beta products (SQL 2005 CTP and VS 2005 Beta 2.0) manually, then installed the VS 2005 RTM and it seems to work fine (I also have VS 2003 and VS 2002 installed on this box).I tried running msiinv but I see nothing
related to SQL Server installed. I tried running Windows Cleanup Utility (msicuu2.exe) but also saw nothing related to SQL. I looked in the registry and saw under hklmmicrosoftmicrosoft sql server an 80 folder and a 90 folder.
The 80 folder was related to a prior SQL 2000 install which I believe was removed when I installed the SQL 2005 CTP. There are no instances showing up in thesse registry keys. I also looked in services and find no sql related services running. I also removed left over folders and files at C:Program FilesMicrosoft SQL Server prior to install (I did save them elsewhere so I have all the install logs).
Thanks for any help you can give me.
Steve Shier
Hi Steve – Can you please contact me at Aaron.Stebner (at) microsoft (dot) com and zip and send me the log files located at %ProgramFiles%Microsoft SQL Server90Setup BootstrapLogFiles so I can try to take a look and see if I can figure anything out?
I uninstall it from youtunsinstaller, but during the work, the computer reboot
No more uninstall link
I have followed the manual uninstallation tips.
When I try to install the new version, it bloc saying : it is allready install …
I see the smartmsizap.exe" /p
and try {.NET Framework 2.0} but it doesn’t work, what is the product code ????
Thx for help
Hi Kendo – You need to use the MsiInv tool linked in step 1 above to determine the product code. Can you please try that out and see if you can figure it out from there?
A customer contacted me this week after reading my blog post about uninstalling beta builds of VS 2005…
hi Aaron
Thanks for this post. Unfortunately I’m not able to download the smartmsizap tool… Is it still online ?
Thanks
Hi Panzerkunst –.
Hi. I installed visual basic beta 2 and had given up until I finally found this information. The uninstall tool was giving me some XML error and would not finish the uninstall. Once I ran your information here the betas autouninstall completed and when I ran your msiInv tool the programs didn’t show up anymore however the folders "Microsoft SQL Server" and "Microsoft Visual Studio 8" and its files are still in my programs folder and when I startup my computer "sqlservr.eve" is running. Please help I don’t know what else to do.
Hi Cass – The MsiInv and SmartMsiZap workaround is designed to remove the beta version so that you can install the final release of the product. This workaround does not remove all of the files for a product though, so that would probably explain why you still see those folders. Is your goal to install the final release or to just remove the beta? If you want to install the final release, I would suggest installing it now. If you want to only remove the beta, I would suggest manually deleting the SQL Server service and deleting the folders you mention above manually. Hope this helps….
Hi, my goal was not to install the final release but to remove it all together. I didn’t want to remove the folders without being sure that if I did I wouldn’t start getting some system error because sqlservr.exe seems to run on its own. Also, I wanted to make sure that I removed all the files that may have been installed in other directories associated with it so that I wouldn’t have all these extra files still on my computer. Thanks for your help.
Hi, Aaron
Because of a problem with my anti virus, I had to uninstall Visual Basic Express Edition (and .Net Framework 2.0, MSDN, and optional SQL that was installed during VB installation). Unfortunately, I uninstalled first .Net Framework 2.0 and after I realized that it had to be installed to be able to uninstall VB, so I re-installed .Net Framework 2.0 back and continue uninstalling the rest. At the end, I uninstalled .Net Framework 2.0.
After that, I tried to install again VB and optional SQL (now with the anti virus disabled, that was the problem in my first installation). But this second time, I was not asked if I wanted SQL installed (the first time, I was asked about SQL and I said yes). So, I do not have SQL installed, although I see a lot of folders and files related to SQL. I look in Control Panel -add/remove programs- and nothing related to SQL appears.
Can you tell me how to force the installation of SQL? If not possible, are MsiInv and SmartMsiZap tools good for uninstalling everything again and reinstall once more? I have the CD burned from the ISO image file downloaded from Microsoft.
Many Thanks in advance for your help.
Hi Iafossi – I would suggest first trying to download and install SQL Express directly by using the link at.
MsiInv and SmartMsiZap would probably help here, but it would be more reliable for you to try to repair SQL Express using the official setup package first.
Hope this helps!
Many thanks, Aaron
I will try your suggestion and let you know the result.
Ignacio
Hi Aaron
I downloaded and installed SQL Express directly following your advise and it seems that everything is right now. Many thanks for your help.
Ignacio
PingBack from
Thanks so much – this saved me a whole afternoon of pulling my hair out.
we can use recommended uninstaller like mirekusoft () or revo to uninstall applications on Windows. It can help solve problems that are caused when a program does not uninstall properly.
Hi,
I installed OfficeScan Server on my machine.I am trying to uninstall it and cant do it.Its visible in the add or remove programs and even as a menu item but there's no Product Code GUID for it and some I am not able to use the fix it tool.
I used msiinv.exe and it showed no key for Trend Micro.
Please guide me through….
Thanks a lot. | https://blogs.msdn.microsoft.com/astebner/2005/10/30/how-to-uninstall-an-application-when-it-does-not-appear-in-addremove-programs/ | CC-MAIN-2016-44 | refinedweb | 1,613 | 74.08 |
Leave Comments, Critiques, and Suggestions Here?
In order to compile DLL file you'll have to modify your sc.ini file, add this to sc.ini file
[Environment]
LIB="%@P%\..\lib"
DFLAGS="-I%@P%\..\import" -version=Tango -defaultlib=tango-dmd.lib -debuglib=tango-dmd.lib tango-dmd.lib
LINKCMD=%@P%\link.exe
main difference is that vanilla sc.ini file has "-L+tango-dmd.lib", while in order to compile and link DLL you got to leave out "-L+". So, if you want to create DLL files, it would be best to have two sc.ini files - one for usual compilation and one for DLL's.
Here is the source for simple DLL file:
module mydll;
import tango.sys.win32.Types;
import tango.io.Stdout;
import tango.stdc.stdio;
// The core DLL init code.
extern (C) bool rt_init( void delegate( Exception ) dg = null );
extern (C) bool rt_term( void delegate( Exception ) dg = null );
HINSTANCE g_hInst;
extern (Windows)
BOOL DllMain(HINSTANCE hInstance, ULONG ulReason, LPVOID pvReserved)
{
switch (ulReason)
{
case DLL_PROCESS_ATTACH:
rt_init();
break;
case DLL_PROCESS_DETACH:
tango.stdc.stdio._fcloseallp = null;
rt_term();
break;
case DLL_THREAD_ATTACH:
case DLL_THREAD_DETACH:
// Multiple threads not supported yet
return false;
}
g_hInst=hInstance;
return true;
}
// End of core DLL Init
export extern(C) void dllprint() { Stdout.formatln("hello dll world\n"); }
As you can see, this is a usual DLL structure, we have a rt_init and rt_term functions which are called when DLL is loaded and when it is detached, nothing fancy in here.
Be sure to include import tango.sys.win32.Types; as it is needed for Windows types information. That is all you need for this program.
In this example DLL we have a simple function dllprint which prints "hello dll world" when called. It has a external C linkage and we imported tango.io.Stdout in order to use Stdout.formatln function. So, basically we have a hello world function in this dll.
In order to compile this example to dll, we also need a .def file which defines our dll. Here it is:
LIBRARY "mydll.dll"
EXETYPE NT
SUBSYSTEM WINDOWS
CODE SHARED EXECUTE
DATA WRITE
EXPORTS
dllprint
You keep track, in your DLL, of EXPORTS where you define your function names and LIBRARY "mydll.dll" where name of the dll resides. Pretty simple, huh? So now, we have two files - mydll.d and mydll.def. On with the compilation.
To compile and link this file you have to set your environment as previously described and type this line to compile it:
dmd -ofmydll.dll mydll.d mydll.def
import tango.sys.SharedLib;
import tango.util.log.Trace;
// declaring our function pointer
typedef extern (C) void function() tdllprint;
tdllprint dllprint;
void main() {
if (auto lib = SharedLib.load(`mydll.dll`)) {
Trace.formatln("Library successfully loaded");
void* ptr = lib.getSymbol("dllprint");
if (ptr) {
Trace.formatln("Symbol dllprint found. Address = 0x{:x}", ptr);
// binding function address from DLL to our function pointer
void **point = cast(void **)&dllprint;
*point = ptr;
// using our function
dllprint();
} else {
Trace.formatln("Symbol dllprint not found");
}
lib.unload();
} else {
Trace.formatln("Could not load the library");
}
assert (0 == SharedLib.numLoadedLibs);
}
As you can see, binding a function from DLL is trivial. Note that you should compile this example with default environment, that is with "-L+" in your sc.ini - as you compile other normal programs. | http://www.dsource.org/projects/tango/wiki/TutDLL | CC-MAIN-2018-26 | refinedweb | 548 | 61.33 |
hi,
i am trying to make an evolution package that includes support for a palm pilot. i got the PKGBUILD file from somebody else and copied it to a directory. In that directory I then executed
makepkg
and tried to compile it. It goes pretty smooth until it complains about the following thing:
error: C compiler cannot create executables
i dont really know how to solve that problem and any help would be appriciated.
thanks
Offline
Try the basics...
Create a file with the following text:
#include <stdio.h> int main() { printf("Hello world"); return 0; }
Save the file has hello.c and compile it with
gcc -Wall hello.c -o hello
and see if you get any errors... you might be having issues with packages like glibc or gcc that would maybe need to be reinstalled
Normally, if it claims that gcc can't create exec's, you should see an error before that warning that would tell you what the problem is
DaDeXTeR (Martin Lefebvre)
My screenshots on PicasaWeb
[img][/img]
Offline
hmm, i did that and it really doesnt work:
[hbadekow@henrik16 hbadekow]$ gcc -Wall test.c -o test /usr/bin/ld: unrecognized option '--as-needed' /usr/bin/ld: use the --help option for usage information collect2: ld gab 1 als Ende-Status zurück
what does that mean?? how can i fix that? any ideas?
thank you for your help!!!!!
Offline
problem soved!!!
the version i had didnt support the option --as-needed and i just updated binutils/ld and it worked!!!
thanks again though!!!
Offline
yet another reason why you should keep your system up to date
Offline | https://bbs.archlinux.org/viewtopic.php?pid=47852 | CC-MAIN-2016-22 | refinedweb | 272 | 73.17 |
Xodoc localization mtg notes 102707
From OLPC
OLPC Doc/Localization Meeting - 10/27/07 - 11am-5pm EST
This agenda is for Saturday for anyone who ends up having a thought they think should be addressed and for the dynamic agenda. if you have some questions/thoughts, please add a section at the bottom of the document and indicate name after question/thought etc.
Notify when agenda/call is set up: > michael cooper, dan samper, brent (todd contact)
Agenda
11:00-11:30 hello how are you
11:30-12:30 localization call
14:00-15:00 strategy and Q/A (Anne can attend at this time or earlier)
Ground to cover > review of groups (doc, etc.) > status of translations, quotes, deadlines > strategy for commercial/open source.
Logistics Does olpc have a voice conferencing solution? Yes, SJ referred to a number. Can we whip up an adobe connect professional account in time (purpose: to capture mtg for others and serve as precedent to capture future meetings as training/get acquainted for future people)
Questions Q: What is the best way to determine dates and priorities for documentation? Are the children third priority, parents any priority as an audience, and are teachers first priority? A: See the 2 tiers of doc and corresponding audiences.
Q: What priority should we make the technical staff, such as those keeping the school server running (is that just a subset of the teacher audience?) A: Audience for 2nd tier docs.
Q: Is a printed manual a possibility or even desired? A: It's a possibility, but only with the individual wanting it, they'd go through lulu.com to get it printed.
Q: Should we try to write separate documentation for the school servers? A: Likely part of the tier 2 docs, community-based.
Q: How is laptop.org currently recognizing contributions on a personal level and on a company level? Would it help to put together a "request for sponsorship" for translation, illustrations, or template design? -Anne
Q: Does laptop.org have a set of design guidelines? If we were to request creation of print/PDF templates, would the designer work with the website designers? Is there a need for consistent messaging from laptop.org? A: The Style Guide on the wiki.laptop.org should be a place for that. There's no printed/PDF template need from laptop.org.
Q: How can we maintain a relationship with the documentation person that laptop.org hires (not duplicating work, communicate with him or her, and so on)? A: They still have not identified the right person who is highly wiki-fluent but will continue working on that. A weekly meeting will help us continue to keep documentation progressing and will help with communication and direction.
Notes Attendees @ 2:00 EST: SJ, Todd, Dan, Anne
Documentation needs: Two tiers of documentation: 1st tier: Quick start doc -suitable for kids (think sixth grade reading level) or anyone who is not necessary highly technical or new to computers and so on -very visual, lots of graphics, low text, minimalism, online -easy to localize Outline for Quick start doc: How to use the laptop Basic troubleshooting, how to get help Show off activities, especially the core activities This doc will be online, but a smaller body of work than the 2nd tier (i.e. more of the online documentation will be in the 2nd tier.) SJ mentioned a Korean game that uses only symbols for language, Todd will get the name so we can look to that for an example.
2nd tier: Technical docs -suitable for higher literacy audience, meaning technology literacy would contain technical specs allows people to start making add-ons, publish "hacks" lots of community support surrounding this documentation - community created, community interactive FAQs, forums, everything with dynamic answers
Other doc needs - need to regularly publish the docs to this wiki.laptop.org wiki to ensure knowledge that it exists. - need to ensure that doc can be printed at lulu.com. SJ notes that an independent distributor would be the way to go here, likes lulu.com, also amazon has something similar. - would like to get some pencil sketch designs from Pentagram, their logo designers, for help pages on the wiki that would have different CSS styling (new namespace). This would allow us to wikislice the OLPC wiki. Anne talked with Michael Priestly about this possibility and will continue to follow up on that concept. - Wiki needs style guide - Anne will work on the page that SJ started at. Anne will get Michael Cooper's permission to use the email that he posted to the devel (or Sugar?) list about writing for translation.
Localization Localization for the software strings happens with the Pootle system, an open source translation string management solution. When you make an activity, you create pootle files. Pootle keeps track of a collection of strings thrat are displayed in the software - it's a collection of string IDs. See also.
There is currently no "open" (as in open source) translation memory available for all to use. Todd has been involved with TRIM - an Instant Messaging solution with multiple languages translated while you type, using machine translation memory.
Michael at dotsub - a video subtitling company - joined us midway. He is interested in an open trnslation collection - they have wikiwords currently, part of an organization with 160K translators. He'll join the localization mailing list and is willing and able to help.
Action items: Anne to work on the Style Guide page Anne to seek out game writers for ideas and/or assistance Todd to get the name of the Korean game with symbols as a language | http://wiki.laptop.org/go/Xodoc_localization_mtg_notes_102707 | CC-MAIN-2016-26 | refinedweb | 941 | 54.32 |
I log in with the jupyter notebook, and open two books. The script that I show below (as an example), in one of the notebooks shows me the image correctly. In the other it shows me the message "Loading BokehJS …"
import numpy as np # bokeh basics from bokeh.plotting import figure from bokeh.io import show, output_notebook x = [1,2,3,4,5] y = [2,4,6,8,10] #output_file('line.html') fig = figure(title = 'Line Plot example', x_axis_label = 'x', y_axis_label = 'y') fig.line(x,y) # Set to output the plot in the notebook output_notebook() show(fig)
What can be the cause of this problem? Could it be related to the fact that the first thing I ran was this program but using the output_file () function to store the output in an HTML file? How can I avoid this problem?
Information taken with! Bokeh info
Python version : 3.8.3 (default, Jul 2 2020, 16:21:59) IPython version : 7.16.1 Tornado version : 6.0.4 Bokeh version : 2.1.1 BokehJS static path : /home/enri/anaconda3/envs/plotly/lib/python3.8/site-packages/bokeh/server/static node.js version : (not installed) npm version : (not installed) | https://discourse.bokeh.org/t/the-bokeh-graph-is-not-displaying-in-jupyter-it-just-says-loading-bokehjs/6770 | CC-MAIN-2020-50 | refinedweb | 197 | 69.99 |
Assemble messages from Akka Actors
As our service grow, it comes to a point we need to interact with more than one data sources (could be db, or another service), gather responses from them, massage them into one thing and return to the user.
A simple use case looks like this
- We have an actor say DataGeneratorActor.
- We send out 2 actors to collect data for us.
Now here are 2 possibilities:
- The 2nd actor depends on 1st actor’s response to act: Sequence
- The 2nd actor doesn’t care what 1st actor carry back: Parallel
Sequence
For sequence case, it’s straight forward to do this:
val data1Actor = ... //create actor#1
val data1ObjFuture: Future[Data1Obj] = (data1Actor ? GetData1()).mapTo[Data1Obj]
val data2Actor = ... //create actor#2
val originalSender = sender()
val anyFuture = data1ObjFuture.onComplete{
case Success(x) =>
val data2ObjFuture = data2Actor ? GetData2(x)
data2ObjFuture.pipeTo(originalSender)
...
}
Run it.
Above
onComplete pattern works just fine for 2 actors, but what if we have like 10 ?
data1ObjFuture.onComplete{
data2ObjFuture.onComplete{
data3ObjFuture.onComplete{
...
As you can see this become super nested very fast.
Good news is Scala offer a syntactic suger called “for comprehensions”:
val data1Actor = ... //create actor#1
val data2Actor = ... //create actor#2
val result = for {
data1Obj: Data1Obj <- (data1Actor ? GetData1()).mapTo[Data1Obj]
data2Obj <- data2Actor ? GetData2(data1Obj)
} yield data2Obj
So the
for … yield above is a syntactic suger for this
futureData1Obj.flatMap(r1 => futureData2Obj.map(r2 => ... ) )
I have to admit, it does make reading easier.
Above example, data2Actor depends response of data1Actor to work. What if it doesn’t ? Is it possible to run these 2 in parallel ?
Yes.
Parallel
Let’s try the following:
val data1Actor = ...
val data3Actor = ...
val dataMergeActor = ...
val report = for {
data1ObjResult <- (data1Actor ? GetData1()).mapTo[Data1Obj]
data3ObjResult <- (data3Actor ? GetData3()).mapTo[Data3Obj]
} yield dataMergeActor ? GetMergedData(data1ObjResult, data3ObjResult)
so data1Actor and data3Actor doesn’t care about what each other returns, will above run in pararell ?
In below example, let’s allow actor to sleep for some time before return.
If data1Actor sleep a little bit longer than data3Actor, the later one will have the chance to come back earlier:
//Data3Actor.scala
class Data3Actor(..., sleepTime: Option[Int]) extends Actor {
...
def receive = {
case _: GetData3 =>
...
sleepTime match {
case Some(time) =>
sleep(time)
case None => ()
}
...
val res:Data3Obj = new Data3Obj(count_Data3)
sender ! res
run it
nope
Looks like data3Actor waits for data1Actor to finish before doing anything, but why ?
Well the
for … yield is not black magic, it is a syntatic suger, so above will translate into a nested .mapTo, hence it’s still sequential.
Then what to do ?
Future in scala by itself is concurrent, no black magic needed. All we need is get the returned future object first, then resolve them in
for … yield.
val data1Actor = ...
val data3Actor = ...
val dataMergeActor = ...
.
val data1ObjFuture: Future[Data1Obj] = (data1Actor ? GetData1()).mapTo[Data1Obj]
val data3ObjFuture: Future[Data3Obj] = (data3Actor ? GetData3()).mapTo[Data3Obj]
val report = for {
data1ObjResult <- data1ObjFuture
data3ObjResult <- data3ObjFuture
} yield dataMergeActor ? GetMergedData(data1ObjResult, data3ObjResult)
Shall we test it out ?
Hey, data3Actor did come back sooner !
I’m also exploring another way to assemble actors’ response, it looks like a state machine. Will probably create another post later. | https://medium.com/@linda0511ny/assemble-messages-from-akka-actors-c3a7cab08a81 | CC-MAIN-2019-13 | refinedweb | 515 | 52.26 |
.
#include <iostream>
#include <fstream>
#include <iomanip>
wchar_t const outtext[] = L"hello world";
char const BOM[] = { 0xFF, 0xFE };
size_t const insize = sizeof(outtext) + sizeof(BOM);
int main()
{
std::ofstream out("c:/temp/myfile.txt", std::ios::binary);
out.write(BOM, sizeof(BOM));
out.write((char *)outtext, sizeof(outtext));
out.close();
wchar_t intext[insize];
std::ifstream in("c:/temp/myfile.txt", std::ios::binary);
in.read((char *)intext, insize);
in.close();
std::cout.write((char *)intext, insize); // wide stream
std::cout << "\n";
char * ptext = (char *)intext;
for(size_t i = 0 ; i < insize ; ++i)
{
std::cout << std::hex << (0xFF & (int)ptext[i]);
}
}
Select all
Open in new window
// UnicodeToMultibyte.cpp : Defines the entry point for the console application.
//
#include "stdafx.h"
#include <iostream>
#include <fstream>
#include <iomanip>
wchar_t const outtext[] = L"*BEGINDATA*";
char const BOM[] = { 0xFF, 0xFE };
char const MALE[] = { 0x37, 0x75 };
size_t const insize = sizeof(outtext) + sizeof(BOM) + sizeof(MALE);
int _tmain(int argc, _TCHAR* argv[])
{
std::ofstream out("c:/temp/myfile2.txt", std::ios::binary);
out.write(BOM, sizeof(BOM));
out.write((char *)outtext, sizeof(outtext));
out.write(MALE, sizeof(MALE));
out.close();
wchar_t intext[300]; //big enough to hold all of chinacd.vpd
std::ifstream in("c:/temp/myfile2.txt", std::ios::binary);
in.read((char *)intext, insize);
in.close();
char * ptext = (char *)intext;
/* std::cout.write((char *)intext, insize); // wide stream
std::cout << "\n";
char * ptext = (char *)intext;
for(size_t i = 0 ; i < insize ; ++i)
{
std::cout << std::hex << (0xFF & (int)ptext[i]);
}
*/
std::ifstream chinaIn("c:/imswin/data/chinacd.vpd", std::ios::binary);
chinaIn.read((char *)intext, 296); //295 is sizeof chinacd.vpd
chinaIn.close();
return.
Encoding mbcs = Encoding.GetEncoding(936);
string mbName = @"c:\imswin\data\china_mb.
StreamReader srMbcs = new StreamReader(mbName, mbcs);
string str = srMbcs.ReadLine();
srMbcs.Close();
If I don't specify the encoding, the files are read correctly when they were created with a Unicode format. In this case, the files had an ASCII? Unicode format so that \U7537 was written as 0Xe7 94 b7.
string ucName = @"c:\imswin\data\china_uc.
StreamReader sr = new StreamReader(ucName);
string unicodeString = sr.ReadLine(); //\U7537
sr.Close();
Currently it is almost impossible to detect encoding of the file without a BOM. Whenever I read the multibyte file, it always is read with UTF-8 encoding, even though this is the wrong encoding for this file. IsTextUnicode always returns true. Here are some other references that indicate how difficult it is.
Rick Strahl's web log.
Complex way to detect how file is encoded
My solution is to translate the Unicode strings to Multibyte character set strings before creating the file that will be read by the legacy multibyte app. That way, the file will always be in the correct format for reading multibyte character set.
Encoding unicode = new UnicodeEncoding(true, false); // Convert the string into a byte[].
byte[] unicodeBytes = unicode.GetBytes(unicodeSt
// Perform the conversion from one encoding to the other.
Encoding mbcs = Encoding.GetEncoding(936);
byte[] mbcsBytes = Encoding.Convert(unicode, mbcs, unicodeBytes);
What format is the file. You say Unicode, but that is not a format that is a character set. Is it UTF8, 16 or 32? I would guess UTF16 since this is what Microsoft generally call Unicode.
When you say your MFC app is Multibyte. What format is that? UTF8, ANSI (or even UTF16 because, contrary to what Microsoft would have you belief UTF16 is also a multibyte encoding format)?
Generally the simplest way to handle Unicode files for cross platform/application pollination is UTF8 because this is easy to handle on all platforms and the basic data types are alway char. If course if your C# app is creating UTF16 you are probably stuck with that so the best solution, in my view, would be to read the file as UTF16 and convert internally.
The tools for Unicode Character Encoding on Windows are pretty poor. I'd suggest you consider using ICU, which is a cross-platform Unicode handling framework from IBM. It's free and open source.
How can I tell what the format is of the MFC Application? I look in properties and see only 2 relevant properites. One is "Using Multibyte Character Set." The other is in the pre processor C++ properties and is "MBCS." So the application is not Unicode. I would probably guess that the files are read with ANSI encoding.
I am now working on this solution: Create a small consule app in Unicode Visual C++ which can read the file. Then try to convert it to Chinese using WideCharToMultibyte. I wish that I could make conversions without going through a separate application. However, I don't know how to write a multibyte file using Unicode strings in C#. Also I have only garbage when I read a Unicode file in a Visual C++ Application built with MBCS..
>> So the application is not Unicode.
That doesn't mean anything other than it will use wide and not narrow char types - this is why I really hate the fact Microsoft call it Unicode. It's not. There are three things that come into play when dealing with text:
1. The data type - wide (wchar_t) or narrow (char). When UNICODE and UNICODE_ is defined the natural char type is wide and wide versions of C and API functions are called. These expect UTF16 encoding. When MBSC is defined the natural char type is narrow.
2. The character encoding. This could be ANSI (think code pages), UTF8 or UTF16 (or other, but we'll consider these just for simplicity). UTF16 is the standard for UNICODE and ANSI is the standard for MBCS
3. The character set. Unicode is a 32 bit character set, UTFx is a way of encoding these 32 bit into smaller data types, which could be wide or narrow.
So, you see, it matters not one little bit if your app is build with MBCS or UNICODE when it comes to reading a file. What matters is you know what the format is and you treat it accordingly. If it's UTF16 you can read that regardless of what type of app you've built. You just need to read it into wide (wchar_t) types and treat it as UTF16. If you want to handle it as UTF8 or ANSI you will need to re-encode it. You can do that using ICU or there are some API functions provided by Windows.
That's what the BOM is there for - to help you figure this out. You should open the file and read it as a series of bytes. Process the BOM and then tread that series of bytes either as a series of chars or a series of wchar_t.
But, I say again - look at using ICU as it will take care of all of this for you... and it's really simple to use.
>> My MBCS app has to be able to read both Unicode and Multibyte (ANSI) files.
As I said above, it can. Forget it's a MBCS app... it's not relevant and is just confusing you. Think only about the file. It's a Unicode file, with a BOM. You need to open it and handle it in this way - the fact your app is MBCS doesn't change or even hinder that.
I am going to try now to read the file using your suggestion to use unicode functions. I hesitate to use site.icu because I work for a corporation that doesn't like programmers to use 3rd party tools without permission. I will give you partial credit if your advice succeeds. I would also like to mark your suggestions as helpful, but I don't know if that will close my question, and I haven't solved the problem yet.
You should just be opening it as a binary file.
fstream in("myfile.txt", std::ios::binary);
or
fopen("myfile.txt", "rb");
There is no rush to close this -- I'm not in it for the points, so take your time. We'll work it out together and get to a point (I hope) where you understand what is going on.
Open in new window
FILE *fh = fopen(pathName, "rb");
const int MAX_COUNT = 100;
char buffer[MAX_COUNT];
memset(buffer, 0, MAX_COUNT);
fread(buffer, 1, 1, fh); <-- buffer[0] contains an asterisk
The first line of the Unicode file begins with
FF FE 2A 00 42 00
FF FE is the BOM. After that comes the string, "*BEGINDATA*". As you see, fread, even with "rb" skips the BOM. Also, I can't override the encoding with the ccs option. If I try ANSI, the program crashes because you aren't allowed to have ANSI if the BOM is FF FE.
Next I tried fstream. In this case, I seem to always get 0xcc or 204 no matter what.
CString pathName = fileDlg.GetPathName();
fstream in(pathName, std::ios::binary);
byte by;
in.read((char *)&by, 1);
in.read((char *)&by, 1);
in.read((char *)&by, 1);
in.close();
fread(buffer, 1, 1, fh);
This will read in 1 byte only.
The spec for fread is as follows.
size_t fread ( void * ptr, size_t size, size_t count, FILE * stream );
Your code should be either
fread(buffer, sizeof(buffer), 1, fh);
or
fread(buffer, 1, sizeof(buffer), fh);
Try the code I posted above, it works -- I know, I tested it :)
>> Maybe I have to try a different app type.
Please trust me... it is nothing to do with the app type... forget about this as you are just confusing yourself. Nothing, I repeat nothing about the app type is going to prevent you reading the file as a series of bytes that you can then treat as UTF16.
This is the default value assigned by the debugger to an uninitialised char -- your file stream is NOT being opened successfully. In other words, the reason it's failing is because you are not reading anything.
read is not working! insize is 26 which is not quite correct. The size should be 24. Because outtext is 11 chars * 2 = 22. 0xFF, 0xFE is probably counted as 4 bytes but should be counted as 2 bytes.
CString pathName = fileDlg.GetPathName();
fstream in(pathName, std::ios::binary);
wchar_t const outtext[] = L"*BEGINDATA*";
char const BOM[] = { 0xFF, 0xFE };
size_t const insize = sizeof(outtext) + sizeof(BOM);
wchar_t intext[insize];
char * ptext = (char *)intext;
in.read((char *)intext, insize);
in.close();
Verbatim? I tested it with VS2008 and it does exactly what I would expect. You should see it output "hello world" followed by another line with the hex that represents the wide chars.
>> If the first byte is 0xFF, then I have a Unicode file.
Maybe... but not necessarily.
>> And yet somehow the read is not working!
It would seem so... try putting in some additional code to check the file is open and also that the stream has not gone into an error state.
>> insize is 26 which is not quite correct.
Sure it is... don't forget there is a null at the end of L"hello world"
0x0012f1d4 "*BEGINDATA*"All RespondeÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌÌ
intext defined as wchar contains garbage Chinese characters. The first character is
0x422a L'¿'
I also tried this in a Unicode app. You are right there is no difference.
I looked at your file "mytext.txt" in a hex editor. The first 3 bytes were FF FE 68 00 65 00
Your file reads great. The first byte of infile is 0xFFFE as expected.
My file in the hex editor is FF FE 42 00 62 00
My file reads like garbage in my apps. I am very puzzled.
How are you reaching this conclusion? When I step through the debugger the two bytes are clearly there. You are just reading a binary file. As long as you have opened it as a binary file C++ makes absolutely no translations on any of the content read. I can only assume you are not correctly opening the file -- do you check this?
>> I also tried this in a Unicode app. You are right there is no difference.
Ta daah :)
>> My file reads like garbage in my apps. I am very puzzled.
Ok, please attach your file and your code (full, so I can compile it and test it).
I still have a problem, but it is not the problem I thought it was. I thought that my source code was reading the file improperly. Instead, the source code was reading correctly. It was the hex dump from UltraEdit that was incorrect.
I attach the file and source code as you requested, but the source code works. It reads my file as a Unicode file and reverses each 2 character byte, which results in garbage. This file is not a Unicode file so I shouldn't read it as Unicode, I guess. But now I'm puzzled. How can this file be distinguished from a multibyte character set file. I need to be able to read both files and display them properly. C# .NET can read the first one ok. C++ multibyte app using CFile and CArchive can read the second one ok. How can I know how to tell the difference between these files when they both start the same way? chinvp.txt
ChinaCD.txt can be translated correctly into Chinese characters by Excel, Outlook, UltraEdit, Notepad.
ChinVP.txt also seems to display "properly" by Notepad, etc. It looks funny with an English (United States) locale. But it displays Chinese characters fine with Hong Kong S.A.R locale. Do you think I can read both files in the same application? Will your classes that you recommended earlier do this job?
Open in new window
I refer you back to this: http:#34125019
You have to figure it out by analysing the content. It is for this reason I strongly suggest you consider ICU. Trying to write a Unicode decoder is not a trivial task -- this is why ICU is used by so many big named companies.-
Consider the various possible encodings you need to try and detect. Now consider that a BOM is completely optional... it might not even exist (as you've discovered). The only way to know how it's encoded is to parse it and figure it out.
I appreciate what you said about needing to get this cleared but the effort in trying to code a proper Unicode parser is going to be significant if you need to handle any possible combination. It's not so painful if you can assume it'll always be a specific format but from what you've said I don't think that is the case for you.
Also, I have no objection if you want to keep this question open whilst you still try and figure out what you are doing in the C++ side of things but as from now I will be offline for the next 5 days (it's my birthday and I'm going to party it up for a few days on a mini-holiday). I will post an alert to some other C++ experts to hopefully keep an eye on things here for you.
-Rx.
Thank you for your kind words in your closing comment. The appreciation means more than any points (although those are nice too) :)
not-so-evilrix. | https://www.experts-exchange.com/questions/26611612/How-to-read-Unicode-files-in-Visual-C-Multibyte-Application.html | CC-MAIN-2018-17 | refinedweb | 2,551 | 76.11 |
The Java Executor Framework provides the
ThreadPoolExecutor class to execute
Callable and
Runnable tasks with a pool of threads, which avoid you writing lots of boiler plate complex code. The way executors work is when you send a task to the executor, it’s executed as soon as possible. But there may be used cases when you are not interested in executing a task as soon as possible. Rather You may want to execute a task after a period of time or to execute a task periodically. For these purposes, the Executor framework provides the
ScheduledThreadPoolExecutor class.
Task to be executed
Let’s write a very basic task which we can use for demo purpose.
class Task implements Runnable { private String name; public Task(String name) { this.name = name; } public String getName() { return name; } @Override public void run() { try { System.out.println("Doing a task during : " + name + " - Time - " + new Date()); } catch (Exception e) { e.printStackTrace(); } } }
Execute a task after a period of time
package com.howtodoinjava.demo.multithreading; import java.util.Date; import java.util.concurrent.Executors; import java.util.concurrent.ScheduledExecutorService; import java.util.concurrent.TimeUnit; public class ScheduledThreadPoolExecutorExample { public static void main(String[] args) { ScheduledExecutorService executor = Executors.newScheduledThreadPool(2); Task task1 = new Task ("Demo Task 1"); Task task2 = new Task ("Demo Task 2"); System.out.println("The time is : " + new Date()); executor.schedule(task1, 5 , TimeUnit.SECONDS); executor.schedule(task2, 10 , TimeUnit.SECONDS); try { executor.awaitTermination(1, TimeUnit.DAYS); } catch (InterruptedException e) { e.printStackTrace(); } executor.shutdown(); } } Output: The time is : Wed Mar 25 16:14:07 IST 2015 Doing a task during : Demo Task 1 - Time - Wed Mar 25 16:14:12 IST 2015 Doing a task during : Demo Task 2 - Time - Wed Mar 25 16:14:17 IST 2015
As with class
ThreadPoolExecutor, to create a scheduled executor, Java recommends the utilization of the
Executors class. In this case, you have to use the
newScheduledThreadPool() method. You have passed the number 1 as a parameter to this method. This parameter is the number of threads you want to have in the pool.
To execute a task in this scheduled executor after a period of time, you have to use the
schedule() method. This method receives the following three parameters:
- The task you want to execute
- The period of time you want the task to wait before its execution
- The unit of the period of time, specified as a constant of the TimeUnit class
Also note that You can also use the
Runnable interface to implement the tasks, because the
schedule() method of the
ScheduledThreadPoolExecutor class accepts both types of tasks.
Moreover ,although the
ScheduledThreadPoolExecutor class is a child class of the
ThreadPoolExecutor class and, therefore, inherits all its features, Java recommends the utilization of
ScheduledThreadPoolExecutor only for scheduled tasks.
Finally, you can configure the behavior of the
ScheduledThreadPoolExecutor class when you call the
shutdown() method and there are pending tasks waiting for the end of their delay time. The default behavior is that those tasks will be executed despite the finalization of the executor. You can change this behavior using the
setExecuteExistingDelayedTasksAfterShutdownPolicy() method of the
ScheduledThreadPoolExecutor class. With false, at the time of
shutdown(), pending tasks won’t get executed.
Execute a task periodically
Now let’s learn how to use
ScheduledThreadPoolExecutor to schedule a periodic task.
public class ScheduledThreadPoolExecutorExample { public static void main(String[] args) { ScheduledExecutorService executor = Executors.newScheduledThreadPool(1); Task task1 = new Task ("Demo Task 1"); System.out.println("The time is : " + new Date()); ScheduledFuture<?> result = executor.scheduleAtFixedRate(task1, 2, 5, TimeUnit.SECONDS); try { TimeUnit.MILLISECONDS.sleep(20000); } catch (InterruptedException e) { e.printStackTrace(); } executor.shutdown(); } } Output: The time is : Wed Mar 25 16:20:12 IST 2015 Doing a task during : Demo Task 1 - Time - Wed Mar 25 16:20:14 IST 2015 Doing a task during : Demo Task 1 - Time - Wed Mar 25 16:20:19 IST 2015 Doing a task during : Demo Task 1 - Time - Wed Mar 25 16:20:24 IST 2015 Doing a task during : Demo Task 1 - Time - Wed Mar 25 16:20:29 IST 2015
In this example, we have created
ScheduledExecutorService instance just like above example using
newScheduledThreadPool() method. Then we have used the
scheduledAtFixedRate() method. This method accepts four parameters:
- the task you want to execute periodically,
- the delay of time until the first execution of the task,
- the period between two executions,
- and the time unit of the second and third parameters.
An important point to consider is that the period between two executions is the period of time between these two executions that begins. If you have a periodic task that takes 5 seconds to execute and you put a period of 3 seconds, you will have two instances of the task executing at a time.
ScheduledThreadPoolExecutorprovides.
Happy Learning !!
is there any way we can change schedule interval after he start of program. For example, I want to change execution time of a task from 1 AM daily to 2 AM daily.
Nice one..Really helpful
Thanks for your post , these posts on individual topics are very helpful in understanding and later we can mix them for the desired functionality.
Just one correction, In the Note section you might have done Typo and hence it shows “scheduledWithFixedRate” instead of “scheduleWithFixedDelay”.
“If you have a periodic task that takes 5 seconds to execute and you put a period of 3 seconds, you will have two instances of the task executing at a time.” – No two tasks execute at the same time. [Please refer to 5.3 this post] In this case, the subsequent execution happens at every 5 seconds though the delay is 3 seconds. Thanks.
The 1st example, should we put
executor.shutdown();
before
executor.awaitTermination(1, TimeUnit.DAYS);
so the executor can exit after all tasks are done rather than waiting for a day?
awaitTermination(long timeout, TimeUnit unit)
Blocks until all tasks have completed execution after a shutdown request, or the timeout occurs, or the current thread is interrupted, whichever happens first.
IN Execute a task periodically program , the output has 4 statements. Is there any reason why the task executed for 4 times ? Can we configure how many times it should execute ?
I had closed the program after 4 executions. If you let it run indefinitely, it will be executed unlimited number of times.
Can you please let me know where have you initiated to close the program after 4th run?
It will run indefinitely and we are only forcing it to stop executing after 4 times using sleep method.If we change the seconds in sleep from 20 to 30 then it will run 6 times and it will shutdown. Hope u guys Understand!!!! | https://howtodoinjava.com/java/multi-threading/task-scheduling-with-executors-scheduledthreadpoolexecutor-example/ | CC-MAIN-2020-10 | refinedweb | 1,113 | 55.34 |
In my last post to this blog, I examined the ESB-jBPM integration in
the SOA Platform. This time, we'll take a look at one aspect of the
integration with JBoss Rules.
Introduction
The routing of data from one place to another is one of the most basic, and common, problems facing any networked software application. This routing can take many forms, such as email being sent to the correct recipient or network traffic being routed around the globe based on system names defined in DNS.
In the context of an Enterprise Service Bus such as the JBoss ESB in the SOA Platform, where everything is either a message or a service, routing means getting messages delivered to the correct services. There are multiple ways to route data to a service. It's possible to define these routes statically, which can make sense for an application where some type of data is always directed to a set endpoint. But, this approach will fail if a destination service is unavailable or is moved. You can control the route that the messages take across the ESB in a number of ways. In this post, we'll examine routing messages based on message content with the content based routing pattern as illustrated in one of the SOA Platform "quickstart" sample programs.
JBoss Rules
One of the great challenges in developing business application software is the separation between the business logic, or the "rules" that you want to govern the application, and the technical programming tasks necessary to actually build the application. What's more, it can be expensive and difficult to maintain application code, and keep it in synch with constantly changing business conditions and while not destroying the original design and turning the code into a set of ever more complex if-then-else statements. What's needed is a mechanism to define the business rules and then execute the rules without having to hardcode the rules into the application code.
What's needed is a rules engine. JRS-94[1] defines the standard for a Java rules engine API. The standard defines the API to register, retrieve and execute rules. JBoss Drools[2] (referred to as JBoss Rules in the SOA Platform) is based on this standard, but more than just a rules API and rules programming language, Drools is a complete enterprise platform for rules-based application development, workflow, administration, and event processing. It also provides an integration with JBossESB to support content based routing.
Let's start by examining at the term "content based routing."[3] The routing part of the term is easy; we're talking about getting messages routed to the correct service. When we talk about "content based" routing, what we want to have happen is to have the ESB examine a message, and based on its content, select the correct routing path. But, we don't want to have the code to make these routing decisions built into the services or the ESB itself. We want to use a rules-based approach, where we can take advantage of the power and flexibility of a rules definition language to construct the decision making routing. We also want to take advantage of the efficiency of a rules engine to perform this routing, instead of coding complex and hard to maintain if-then-else statements into the application.
OK. It's time to look at a working example.
One of the great features of the SOA Platform is its extensive set of "quickstart" programs. These programs illustrate various features supported by the ESB. For our example, we'll look at the fun_cbr quickstart.
Like many of the quickstarts, fun_cbr starts by placing a message into a queue. A service listening to that queue then takes that message and sends it to a destination service. What we're interested in looking at in this quickstart, is how the content of that message determines the route that the message takes to one of three defined destination services.
Let's start by examining with the message and its content. When you run the quickstart, the "SampleOrder.xml" (for a mythical DVD store) is file is read into the message that is sent. The file looks like this:
In SampleOrder.xml:
<Order xmlns="" orderId="1" statusCode="0"
netAmount="59.97" totalAmount="64.92" tax="4.95">
<Customer userName="user1" firstName="Harry" lastName="Fletcher" state="SD"/>
<OrderLines>
<OrderLine position="1" quantity="1">
<Product productId="364" title="The 40-Year-Old Virgin " price="29.98"/>
</OrderLine>
<OrderLine position="2" quantity="1">
<Product productId="299" title="Pulp Fiction" price="29.99"/>
</OrderLine>
</OrderLines>
</Order>
Nothing
in this content is that unusual (except perhaps for Harry's taste in
movies). Make a mental note of the "statusCode" element on line #1.
We'll come back to this in a bit.
OK, we have build a message that contains this content and place that message in a queue so that a service can receive it and execute an action on it. Now what?
Let's look at that action in the "jboss-esb.xml" file. (This file defines the configuration of, and the actions performed, by the quickstart.)
In jboss-esb.xml:
44 <action class="org.jboss.soa.esb.actions.ContentBasedRouter" name="ContentBasedRouter">
45 <property name="ruleSet" value="FunCBRRules-XPath.drl"/>
46 <property name="ruleLanguage" value="XPathLanguage.dsl"/>
47 <property name="ruleReload" value="true"/>
48 <property name="destinations">
49 <route-to
50 <route-to
51 <route-to
52 </property>
53 </action>
Let's examine this section of the file line-by-line:
Line 44: The org.jboss.soa.esb.actions.ContentBasedRouter class is one of the SOA Platform's predefined "Out-of-the-box Actions." The SOA Platform provides a set of these actions, that you can always augment by writing your own custom actions[4]. Before you write your own, you should take a look at the out-of-the-box actions as you may find one that meets your application's needs.
Line 45: Here's where we define the set of rules that govern the content based routing. Remember that in this context, the rules are defined as JBoss Rules. We'll examine these rules in just a minute.
Line 46: In order to be able to parse information out of XML data in a message, the SOA Platform includes a domain specific language (DSL) implementation to use XPath to traverse the XML. This is defined in the jboss-as/server/production/deploy/jbrules.esb/XPathLanguage.dsl file. If you're unfamiliar with XPath[5], it's really worth learning as it has many useful applications. For example, some GUI automation tools such as Selenium support using XPath to locate UI elements if you are unable to rely on the UI elements having static ID's. Also note that XPathLanguage.dsl supports both namespace specific and non-namespace specific syntaxes. In this quickstart, a namespace specific syntax is used.
Line 47: This property allows you to specify if the rules should be reloaded each time they are used. This has no effect on the small set of rules used in the quickstart, but it can cause a performance hit on a large set of rules. So, setting this to "true" enables you to modify the rules as defined in the copy of FunCBRRules-XPath.drl deployed to the server without having to redeploy the quickstart to the SOA-P server. Modifying the local copy of the rules file will not cause the rules to be reloaded. You have to update the drl file that is deployed with the quickstart.
Lines 49-51: These are the routes to the destination services.
Now it's time to take a look at the rules that are defined in FunCBRRules-XPath.drl
In FunCBRRules-XPath.drl:
package com.jboss.soa.esb.routing.cbr
#list any import classes here.
import org.jboss.soa.esb.message.Message;
import org.jboss.soa.esb.message.format.MessageType;
expander XPathLanguage.dsl
#declare any global variables here
global java.util.List destinations;
rule "Blue Routing Rule using XPATH"
when
xpathEquals expr "/order:Order/@statusCode", "0" use namespaces "order="
then
Log : "Blue Team";
Destination : "blue";
end
rule "Red Routing Rule using XPATH"
when
xpathEquals expr "/order:Order/@statusCode", "1" use namespaces "order="
then
Log : "Red Team";
Destination : "red";
end
rule "Green Routing Rule using XPATH"
when
xpathEquals expr "/order:Order/@statusCode", "2" use namespaces "order="
then
Log : "Green Team";
Destination : "green";
end
Line 7: Here is the reference to the XPath definitions.
Line 10: The destinations global variable is the point of integration to the destinations defined in the jboss-esb.xml file.
The rules are all the same, except for the status code value, so we'll only examine one of them. (In the process, we'll walk through a short lesson in writing a rule.)
Line 12: The start of a rule definition.
Line 13: The start of the "when" construct of a rule. Each rule definition includes a "when" construct (the criteria that must be met) and a "then" construct (the action to take if the "when" construct is met).
Line 14: The XPath syntax translates to "starting at the root of the document, find an Order element with a statusCode attribute equal to 0."
Line 15: The then construct starts here.
Line 16: Generate a log message
Line 17: Add a destination's name to the global list called "destinations, " which is then evaluated by org.jboss.soa.esb.actions.ContentBasedRouter that invoked the rule.
If you're getting a little lost now, this diagram may shows how things are connected.
So what happens when the quickstart is deployed and run?
- An incoming message is placed into the queue that is watched by the listener configured with the ContentBasedRouter action
- That action is configured with the rule set defined in FunCBRRules-XPath.drl
- The action class puts the message into the Rules' working memory and fires the rules
- Based on the results of the rules, a list of destinations is created
- And the message is sent to the services at those destinations - in the case of this test, the message is sent to the blue team
(There's actually a bit more to it for the incoming message. JBoss ESB actually routes ESB formatted messages to services. The ESB supports adapters to enable other formats for incoming messages. These adapters operate with "gateway" services to enable you to connect existing services to the SOA Platform.[6])
Closing Thoughts
As we discussed in the introduction, one of the great strengths of the SOA Platform is the set of integrations that it supports. With its integration with JBoss Rules, you can deploy Rules-based services to the SOA Platform server and utilize JBoss Rules for content based routing. With content based routing, the information in the messages themselves determine the messages' destinations.
References
[1]
[2]
[3]
[4]
[5]
[6]
Acknowledgments
As always, I'd like to thank the members of the JBossESB (see), JBoss Rules projects, SOA Platform project - especially Burr Sutter, Mark Little, Mark Proctor and Jarek Kijanowski - for their help and timely review comments! Also, this article relies heavily on the extensive JBossESB and JBoss Rules user documents and the quickstarts.
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{{ parent.linkDescription }}{{ parent.urlSource.name }} | https://dzone.com/articles/when-content-knows-way-content | CC-MAIN-2016-40 | refinedweb | 1,883 | 53.71 |
Ada encourages the division of code into separate modules called packages. Each package can contain any combination of items.
Some of the benefits of using packages are:
- package contents are placed in a separate namespace, preventing naming collisions,
- implementation details of the package can be hidden from the programmer (information hiding),
- object orientation requires defining a type and its primitive subprograms within a package, and
- packages can be separately compiled.
Some of the more common package usages are:
- a group of related subprograms along with their shared data, with the data not visible outside the package,
- one or more data types along with subprograms for manipulating those data types, and
- a generic package that can be instantiated under varying conditions.
The following is a quote from the current Ada Reference Manual Section 7: Packages. RM 7(1) (Annotated)
Packages are program units that allow the specification of groups of logically related entities. Typically, a package contains the declaration of a type (often a private type or private extension) along with the declaration of primitive subprograms of the type, which can be called from outside the package, while their inner workings remain hidden from outside users.
Separate compilationEdit
It is very common for package declarations and package bodies to be coded into separate files and separately compiled. Doing so places the package at the library level where it will be accessible to all other code via the with statement—if a more restricted scope is desired, simply declare the package (and package body, if needed) within the appropriate scope. The package body can itself be divided into multiple files by specifying that one or more subprogram implementations are separate.
One of the biggest advantages of Ada over most other programming languages is its well defined system of modularization and separate compilation. Even though Ada allows separate compilation, it maintains the strong type checking among the various compilations by enforcing rules of compilation order and compatibility checking. Ada uses separate compilation (like Modula-2, Java and C#), and not independent compilation (as C/C++ does), in which the various parts are compiled with no knowledge of the other compilation units with which they will be combined.
A note to C/C++ users: Yes, you can use the preprocessor to emulate separate compilation — but it is only an emulation and the smallest mistake leads to very hard to find bugs. It is telling that all C/C++ successor languages including D have turned away from the independent compilation and the use of the preprocessor.
So it's good to know that Ada has had separate compilation ever since Ada-83 and is probably the most sophisticated implementation around.
Parts of a packageEdit
A package generally consists of two parts, the specification and the body. A package specification can be further divided in two logical parts, the visible part and the private part. Only the visible part of the specification is mandatory. The private part of the specification is optional, and a package specification might not have a package body—the package body only exists to complete any incomplete items in the specification. Subprogram declarations are the most common incomplete items. There must not be a package body if there is no incomplete declaration, and there has to be a package body if there is some incomplete declaration in the specification.
To understand the value of the three-way division, consider the case of a package that has already been released and is in use. A change to the visible part of the specification will require that the programmers of all using software verify that the change does not affect the using code. A change to the private part of the declaration will require that all using code be recompiled but no review is normally needed. Some changes to the private part can change the meaning of the client code however. An example is changing a private record type into a private access type. This change can be done with changes in the private part, but change the semantic meaning of assignment in the clients code. A change to the package body will only require that the file containing the package body be recompiled, because nothing outside of the package body can ever access anything within the package body (beyond the declarations in the specification part).
A common usage of the three parts is to declare the existence of a type and some subprograms that operate on that type in the visible part, define the actual structure of the type (e.g. as a record) in the private part, and provide the code to implement the subprograms in the package body.
The package specification — the visible partEdit
The visible part of a package specification describes all the subprogram specifications, variables, types, constants etc. that are visible to anyone who wishes to use the package.
package Public_Only_Package is type Range_10 is range 1 .. 10; end Public_Only_Package;
Since Range_10 is an integer type, there are a lot of operations declared implicitly in this package.
The private partEdit
The private part of a package serves two purposes:
- To complete the deferred definition of private types and constants.
- To export entities only visible to the children of the package
package Package_With_Private is type Private_Type is private; private type Private_Type is array (1 .. 10) of Integer; end Package_With_Private;
Since the type is private, clients cannot make any use of it as long as there are no operations defined in the visible part.
The package bodyEdit
The package body defines the implementation of the package. All the subprograms defined in the specification have to be implemented in the body. New subprograms, types and objects can be defined in the body that are not visible to the users of the package.
package Package_With_Body is type Basic_Record is private; procedure Set_A (This : in out Basic_Record; An_A : in Integer); function Get_A (This : Basic_Record) return Integer; private type Basic_Record is record A : Integer; end record ; pragma Pure_Function (Get_A); -- not a standard Ada pragma pragma Inline (Get_A); pragma Inline (Set_A);;
Two Flavors of PackageEdit
The packages above each define a type together with operations of the type. When the type's composition is placed in the private part of a package, the package then exports what is known to be an Abstract Data Type or ADT for short. Objects of the type are then constructed by calling one of the subprograms associated with the respective type.
A different kind of package is the Abstract State Machine. A package will be modeling a single item of the problem domain, such as the motor of a car. If a program controls one car, there is typically just one motor, or the motor. The public part of the package specification only declares the operations of the module (of the motor, say), but no type. All data of the module are hidden in the body of the package where they act as state variables to be queried, or manipulated by the subprograms of the package. The initialization part sets the state variables to their initial values.
package Package_With_Body is procedure Set_A (An_A : in Integer); function Get_A return Integer; private pragma Pure_Function (Get_A); -- not a standard Ada pragma end Package_With_Body;
package body Package_With_Body is The_A: Integer; procedure Set_A (An_A : in Integer) is begin The_A := An_A; end Set_A; function Get_A return Integer is begin return The_A; end Get_A; begin The_A := 0; end Package_With_Body;
(A note on construction: The package initialization part after begin corresponds to a construction subprogram of an ADT package. However, as a state machine is an “object” already, “construction” is happening during package initialization. (Here it sets the state variable The_A to its initial value.) An ASM package can be viewed as a singleton.)
Using packagesEdit
To utilize a package it's needed to name it in a with clause, whereas to have direct visibility of that package it's needed to name it in a use clause.
For C++ programmers, Ada's with clause is analogous to the C++ preprocessor's #include and Ada's use is similar to the using namespace statement in C++. In particular, use leads to the same namespace pollution problems as using namespace and thus should be used sparingly. Renaming can shorten long compound names to a manageable length, while the use type clause makes a type's operators visible. These features reduce the need for plain use.
Standard withEdit
The standard with clause provides visibility for the public part of a unit to the following defined unit. The imported package can be used in any part of the defined unit, including the body when the clause is used in the specification.
Private withEdit
This language feature is only available in Ada 2005.
private with Ada.Strings.Unbounded; package Private_With is -- The package Ada.String.Unbounded is not visible at this point type Basic_Record is private; procedure Set_A (This : in out Basic_Record; An_A : in String); function Get_A (This : Basic_Record) return String; private -- The visibility of package Ada.String.Unbounded starts here package Unbounded renames Ada.Strings.Unbounded; type Basic_Record is record A : Unbounded.Unbounded_String; end record; pragma Pure_Function (Get_A); pragma Inline (Get_A); pragma Inline (Set_A); end Private_With;
package body Private_With is -- The private withed package is visible in the body too procedure Set_A (This : in out Basic_Record; An_A : in String) is begin This.A := Unbounded.To_Unbounded_String (An_A); end Set_A; function Get_A (This : Basic_Record) return String is begin return Unbounded.To_String (This.A); end Get_A; end Private_With;
Limited withEdit
This language feature is only available in Ada 2005.
limited with Departments; package Employees is type Employee is tagged private; procedure Assign_Employee (E : in out Employee; D : access Departments.Department'Class); type Dept_Ptr is access all Departments.Department'Class; function Current_Department(E : in Employee) return Dept_Ptr; ... end Employees;
limited with Employees; package Departments is type Department is tagged private; procedure Choose_Manager (Dept : in out Department; Manager : access Employees.Employee'Class); ... end Departments;
Making operators visibleEdit
Suppose you have a package Universe that defines some numeric type T.
with Universe; procedure P is V: Universe.T := 10.0; begin V := V * 42.0; -- illegal end P;
This program fragment is illegal since the operators implicitly defined in Universe are not directly visible.
You have four choices to make the program legal.
Use a use_package_clause. This makes all declarations in Universe directly visible (provided they are not hidden because of other homographs).
with Universe; use Universe; procedure P is V: Universe.T := 10.0; begin V := V * 42.0; end P;
Use renaming. This is error prone since if you rename many operators, cut and paste errors are probable.
with Universe; procedure P is function "*" (Left, Right: Universe.T) return Universe.T renames Universe."*"; function "/" (Left, Right: Universe.T) return Universe.T renames Universe."*"; -- oops V: Universe.T := 10.0; begin V := V * 42.0; end P;
Use qualification. This is extremely ugly and unreadable.
with Universe; procedure P is V: Universe.T := 10.0; begin V := Universe."*" (V, 42.0); end P;
Use the use_type_clause. This makes only the operators in Universe directly visible.
with Universe; procedure P is V: Universe.T := 10.0; use type Universe.T; begin V := V * 42.0; end P;
There is a special beauty in the use_type_clause. Suppose you have a set of packages like so:
with Universe; package Pack is subtype T is Universe.T; end Pack;
with Pack; procedure P is V: Pack.T := 10.0; begin V := V * 42.0; -- illegal end P;
Now you've got into trouble. Since Universe is not made visible, you cannot use a use_package_clause for Universe to make the operator directly visible, nor can you use qualification for the same reason. Also a use_package_clause for Pack does not help, since the operator is not defined in Pack. The effect of the above construct means that the operator is not nameable, i.e. it cannot be renamed in a renaming statement.
Of course you can add Universe to the context clause, but this may be impossible due to some other reasons (e.g. coding standards); also adding the operators to Pack may be forbidden or not feasible. So what to do?
The solution is simple. Use the use_type_clause for Pack.T and all is well!
with Pack; procedure P is V: Pack.T := 10.0; use type Pack.T; begin V := V * 42.0; end P;
Package organisationEdit
Nested packagesEdit
A nested package is a package declared inside a package. Like a normal package, it has a public part and a private part. From outside, items declared in a nested package N will have visibility as usual; the programmer may refer to these items using a full dotted name like
P.N.X. (But not
P.M.Y.)
package P is D: Integer; -- a nested package: package N is X: Integer; private Foo: Integer; end N; E: Integer; private -- another nested package: package M is Y: Integer; private Bar: Integer; end M; end P;
Inside a package, declarations become visible as they are introduced, in textual order. That is, a nested package N that is declared after some other declaration D can refer to this declaration D. A declaration E following N can refer to items of N[1]. But neither can “look ahead” and refer to any declaration that goes after them. For example, spec
N above cannot refer to
M in any way.
In the following example, a type is derived in both of the two nested packages Disks and Books. Notice that the full declaration of parent type Item appears before the two nested packages.
with Ada.Strings.Unbounded; use Ada.Strings.Unbounded; package Shelf is pragma Elaborate_Body; -- things to put on the shelf type ID is range 1_000 .. 9_999; type Item (Identifier : ID) is abstract tagged limited null record; type Item_Ref is access constant Item'class; function Next_ID return ID; -- a fresh ID for an Item to Put on the shelf package Disks is type Music is ( Jazz, Rock, Raga, Classic, Pop, Soul); type Disk (Style : Music; Identifier : ID) is new Item (Identifier) with record Artist : Unbounded_String; Title : Unbounded_String; end record; end Disks; package Books is type Literature is ( Play, Novel, Poem, Story, Text, Art); type Book (Kind : Literature; Identifier : ID) is new Item (Identifier) with record Authors : Unbounded_String; Title : Unbounded_String; Year : Integer; end record; end Books; -- shelf manipulation procedure Put (it: Item_Ref); function Get (identifier : ID) return Item_Ref; function Search (title : String) return ID; private -- keeping private things private package Boxes is type Treasure(Identifier: ID) is limited private; private type Treasure(Identifier: ID) is new Item(Identifier) with null record; end Boxes; end Shelf;
A package may also be nested inside a subprogram. In fact, packages can be declared in any declarative part, including those of a block.
Child packagesEdit
Ada allows one to extend the functionality of a unit (package) with so-called children (child packages). With certain exceptions, all the functionality of the parent is available to a child. This means that all public and private declarations of the parent package are visible to all child packages.
The above example, reworked as a hierarchy of packages, looks like this. Notice that the package Ada.Strings.Unbounded is not needed by the top level package Shelf, hence its with clause doesn't appear here. (We have added a match function for searching a shelf, though):
package Shelf is pragma Elaborate_Body; type ID is range 1_000 .. 9_999; type Item (Identifier : ID) is abstract tagged limited null record; type Item_Ref is access constant Item'Class; function Next_ID return ID; -- a fresh ID for an Item to Put on the shelf function match (it : Item; Text : String) return Boolean is abstract; -- see whether It has bibliographic information matching Text -- shelf manipulation procedure Put (it: Item_Ref); function Get (identifier : ID) return Item_Ref; function Search (title : String) return ID; end Shelf;
The name of a child package consists of the parent unit's name followed by the child package's identifier, separated by a period (dot) `.'.
with Ada.Strings.Unbounded; use Ada.Strings.Unbounded; package Shelf.Books is type Literature is ( Play, Novel, Poem, Story, Text, Art); type Book (Kind : Literature; Identifier : ID) is new Item (Identifier) with record Authors : Unbounded_String; Title : Unbounded_String; Year : Integer; end record; function match(it: Book; text: String) return Boolean; end Shelf.Books;
Book has two components of type Unbounded_String, so Ada.Strings.Unbounded appears in a with clause of the child package. This is unlike the nested packages case which requires that all units needed by any one of the nested packages be listed in the context clause of the enclosing package (see 10.1.2 Context Clauses - With Clauses (Annotated)). Child packages thus give better control over package dependences. With clauses are more local.
The new child package Shelf.Disks looks similar. The Boxes package which was a nested package in the private part of the original Shelf package is moved to a private child package:
private package Shelf.Boxes is type Treasure(Identifier: ID) is limited private; private type Treasure(Identifier: ID) is new Item(Identifier) with null record; function match(it: Treasure; text: String) return Boolean; end Shelf.Boxes;
The privacy of the package means that it can only be used by equally private client units. These clients include private siblings and also the bodies of siblings (as bodies are never public).
Child packages may be listed in context clauses just like normal packages. A with of a child also 'withs' the parent.
SubunitsEdit
A subunit is just a feature to move a body into a place of its own when otherwise the enclosing body will become too large. It can also be used for limiting the scope of context clauses.
The subunits allow to physically divide a package into different compilation units without breaking the logical unity of the package. Usually each separated subunit goes to a different file allowing separate compilation of each subunit and independent version control history for each one.
package body Pack is procedure Proc is separate; end Pack; with Some_Unit; separate (Pack) procedure Proc is begin ... end Proc; | http://en.m.wikibooks.org/wiki/Ada_Programming/Packages | CC-MAIN-2014-15 | refinedweb | 3,004 | 53.61 |
#include <FXSpring.h>
Inheritance diagram for FX::FXSpring:
The parameters relw (or relh) determines the length of the spring. The actual length is not really important; the only thing that counts is the relative length of one spring widget to that of another, although the length does determine the default size. The special value zero may be given for relw (or relh) to cause the spring to calculate its default width (height) normally, just like the Packer base class does. In a typical scenario, either the relative width or height is set to zero, an the flag LAYOUT_FILL_X or LAYOUT_FILL_Y is passed. When placed inside a horizontal frame, the LAYOUT_FILL_X together with the relative widths of the springs will cause a fixed width-ratio between the springs. You also can mix normal controls and springs together in a horizontal or vertical frames to provide arbitrary stretchable spacing between widgets; in this case, the springs do not need to have any children. Since the spring widget is derived from the packer layout manager, it provides the same layout behavior as packer. | http://fox-toolkit.org/ref14/classFX_1_1FXSpring.html | CC-MAIN-2021-17 | refinedweb | 180 | 54.26 |
Most ordinary comments within Java
code explain the implementation details of that code. By contrast,
the Java language specification defines a special type of comment
known as a doc comment that
serves to document the API of your code. A doc comment is an ordinary
multiline comment that begins with /** (instead of
the usual /*) and ends with */.
A doc comment appears immediately before a type or member definition
and contains documentation for that type or member. The documentation
can include simple HTML formatting tags and other special
keywords that provide additional information. Doc comments are
ignored by the compiler, but they can be extracted and automatically
turned into online HTML documentation by the
javadoc program. (See Chapter 8 for more information about
javadoc.) Here is an example class that contains
appropriate doc comments:
/**
* This immutable class represents <i>complex numbers</i>.
*
* @author David Flanagan
* @version 1.0
*/
public class Complex {
/**
* Holds the real part of this complex number.
* @see #y
*/
protected double x;
/**
* Holds the imaginary part of this complex number.
* @see #x
*/
protected double y;
/**
* Creates a new Complex object that represents the complex number x+yi.
* @param x The real part of the complex number.
* @param y The imaginary part of the complex number.
*/
public Complex(double x, double y) {
this.x = x;
this.y = y;
}
/**
* Adds two Complex objects and produces a third object that represents
* their sum.
* @param c1 A Complex object
* @param c2 Another Complex object
* @return A new Complex object that represents the sum of
* <code>c1</code> and <code>c2</code>.
* @exception java.lang.NullPointerException
* If either argument is <code>null</code>.
*/
public static Complex add(Complex c1, Complex c2) {
return new Complex(c1.x + c2.x, c1.y + c2.y);
}
}
The
body of a doc comment should begin with a one-sentence summary of the
type or member being documented. This sentence may be displayed by
itself as summary documentation, so it should be written to stand on
its own. The initial sentence may be followed by any number of other
sentences and paragraphs that describe the class, interface, method,
or field in full detail.
After the descriptive paragraphs, a
doc comment can contain any number of other paragraphs, each of which
begins with a special doc-comment tag, such as
@author, @param, or
@returns. These tagged paragraphs provide specific
information about the class, interface, method, or field that the
javadoc program displays in a standard way. The
full set of doc-comment tags is listed in the next section.
The descriptive material in a
doc comment can contain simple HTML markup tags, such as such as
<i> for emphasis,
<code> for class, method, and field names,
and <pre> for multiline code examples. It
can also contain <p> tags to break the
description into separate paragraphs and
<ul>, <li>, and
related tags to display bulleted lists and similar structures.
Remember, however, that the material you write is embedded within a
larger, more complex HTML document. For this reason, doc comments
should not contain major structural HTML tags, such as
<h2> or <hr>, that
might interfere with the structure of the larger document.
Avoid the use of the
<a> tag to include
hyperlinks or cross-references in your doc comments. Instead, use the
special {@link} doc-comment tag, which, unlike the
other doc-comment tags, can appear anywhere within a doc comment. As
described in the next section, the {@link} tag
allows you to specify hyperlinks to other classes, interfaces,
methods, and fields without knowing the HTML-structuring conventions
and filenames used by javadoc.
If you want to include an image in a
doc comment, place the image file in a doc-files
subdirectory of the source code directory. Give the image the same
name as the class, with an integer suffix. For example, the second
image that appears in the doc comment for a class named
Circle can be included with this HTML tag:
<img src="doc-files/Circle-2.gif">
Because the lines of a doc comment are
embedded within a Java comment, any leading spaces and asterisks
(*) are stripped from each line of the comment
before processing. Thus, you don't need to worry
about the asterisks appearing in the generated documentation or about
the indentation of the comment affecting the indentation of code
examples included within the comment with a
<pre> tag.
javadoc recognizes a
number of special tags, each of which begins with an
@ character. These doc-comment tags allow you to
encode specific information into your comments in a standardized way,
and they allow javadoc to choose the appropriate
output format for that information. For example, the
@param tag lets you specify the name and meaning
of a single parameter for a method. javadoc can
extract this information and display it using an HTML
<dl> list, an HTML
<table>, or however it sees fit.
The following doc-comment tags are recognized by
javadoc; a doc comment should typically use
these tags in the order listed here:
Adds
an "Author:" entry that contains
the specified name. This tag should be used for every class or
interface definition but must not be used for individual methods and
fields. If a class has multiple authors, use multiple
@author tags on adjacent lines. For example:
@author David Flanagan
@author Paula Ferguson
List the authors in chronological order, with the original author
first. If the author is unknown, you can use
"unascribed."
javadoc does not output authorship information
unless the -author command-line argument is
specified.
Inserts a
"Version:" entry that contains the
specified text. For example:
@version 1.32, 08/26/04
This tag should be included in every class and interface doc comment
but cannot be used for individual methods and fields. This tag is
often used in conjunction with the automated version-numbering
capabilities of a version control system, such as SCCS, RCS, or CVS.
javadoc does not output version information in
its generated documentation unless the -version
command-line argument is specified.
Adds
the specified parameter and its description to the
"Parameters:" section of the
current method. The doc comment for a method or constructor must
contain one @param tag for each parameter the
method expects. These tags should appear in the same order as the
parameters specified by the method. The tag can be used only in doc
phrases and sentence fragments where possible to keep the
descriptions brief. However, if a parameter requires detailed
documentation, the description can wrap onto multiple lines and
include as much text as necessary. For readability in source-code
form, consider using spaces to align the descriptions with each
other. For example:
@param o the object to insert
@param index the position to insert it at
Inserts a
"Returns:" section that contains
the specified description. This tag should appear in every doc
comment for a method, unless the method returns
void or is a constructor. The description can be
as long as necessary, but consider using a sentence fragment to keep
it short. For example:
@return <code>true</code> if the insertion is successful, or
<code>false</code> if the list already contains the specified object.
Adds a
"Throws:" entry that contains the
specified exception name and description. A doc comment for a method
or constructor should contain an @exception tag
for every checked exception that appears in its
throws clause. For example:
@exception java.io.FileNotFoundException
If the specified file could not be found
The @exception tag can optionally be used to
document unchecked exceptions (i.e., subclasses of
RuntimeException) the method may throw, when these
are exceptions that a user of the method may reasonably want to
catch. If a method can throw more than one exception, use multiple
@exception tags on adjacent lines and list the
exceptions in alphabetical order. The description can be as short or
as long as necessary to describe the significance of the exception.
This tag can be used only for method and constructor comments. The
@throws tag is a synonym for
@exception.
This
tag is a synonym for @exception.
Adds a
"See Also:" entry that contains the
specified reference. This tag can appear in any kind of doc comment.
The syntax for the reference is explained
in Section 7.3.4 later in this
chapter.
This tag specifies
that the following type or member has been deprecated and that its
use should be avoided. javadoc adds a prominent
"Deprecated" entry to the
documentation and includes the specified
explanation text. This text should specify
when the class or member was deprecated and, if possible, suggest a
replacement class or member and include a link to it. For example:
@deprecated As of Version 3.0, this method is replaced
by {@link #setColor}.
Although the Java compiler ignores all comments, it does take note of
the @deprecated tag in doc comments. When this tag
appears, the compiler notes the deprecation in the class file it
produces. This allows it to issue warnings for other classes that
rely on the deprecated feature.
Specifies when the
type or member was added to the API. This tag should be followed by a
version number or other version specification. For example:
@since JNUT 3.0
Every doc comment for a type should include an
@since tag, and any members added after the
initial release of the type should have @since
tags in their doc comments.
Technically,
the way a class is serialized
is part of its public API. If you write a class that you expect to be
serialized, you should document its serialization format using
@serial and the related tags listed below.
@serial should appear in the doc comment for any
field that is part of the serialized state of a
Serializable class. For classes that use the
default serialization mechanism, this means all fields that are not
declared transient, including fields declared
private. The
description should be a brief description
of the field and of its purpose within a serialized object.
As of Java 1.4, you can also use the @serial tag
at the class and package level to specify whether a
"serialized form page" should be
generated for the class or package. The syntax is:
@serial include
@serial exclude
A
Serializable class can define its serialized
format by declaring an array of ObjectStreamField
objects in a field named serialPersistentFields.
For such a class, the doc comment for
serialPersistentFields should include an
@serialField tag for each element of the array.
Each tag specifies the name, type, and description for a particular
field in the serialized state of the class.
A Serializable class
can define a writeObject( ) method to write data
other than that written by the default serialization mechanism. An
Externalizable class defines a
writeExternal() method responsible for writing the
complete state of an object to the serialization stream. The
@serialData tag should be used in the doc comments
for these writeObject( ) and
writeExternal() methods, and the
description should document the
serialization format used by the method.
In addition to the preceding tags,
javadoc also supports several inline
tags that may appear anywhere that HTML text appears in a
doc comment. Because these tags appear directly within the flow of
HTML text, they require the use of curly braces as delimiters to
separate the tagged text from the HTML text. Supported inline tags
include the following:
In
Java 1.2 and later, the {@link} tag is like the
@see tag except that instead of placing a link to
the specified reference in a special
"See Also:" section, it inserts the
link inline. An {@link} tag can appear anywhere
that HTML text appears in a doc comment. In other words, it can
appear in the initial description of the class, interface, method, or
field and in the descriptions associated with the
@param, @returns,
@exception, and @deprecated
tags. The reference for the
{@link} tag uses the syntax described next in
Section 7.3.4. For example:
@param regexp The regular expression to search for. This string
argument must follow the syntax rules described for
{@link java.util.regex.Pattern}.
In Java 1.4 and later, the
{@linkplain} tag is just like the
{@link} tag, except that the text of the link is
formatted using the normal font rather than the code font used by the
{@link} tag. This is most useful when
reference contains both a
feature to link to and a
label that specifies alternate text to be
displayed in the link. See Section 7.3.4 for a discussion of the
feature and
label portions of the
reference argument.
When a method
overrides a method in a superclass or implements a method in an
interface, you can omit a doc comment, and
javadoc automatically inherits the documentation
from the overridden or implemented method. As of Java 1.4, however,
the {@inheritDoc} tag allows you to inherit the
text of individual tags. This tag also allows you to inherit and
augment the descriptive text of the comment. To inherit individual
tags, use it like this:
@param index @{inheritDoc}
@return @{inheritDoc}
To inherit the entire doc comment, including your own text before and
after it, use the tag like this:
This method overrides {@link java.langObject#toString}, documented as follows:
<P>{@inheritDoc}
<P>This overridden version of the method returns a string of the form...
This inline tag takes no
parameters and is replaced with a reference to the root directory of
the generated documentation. It is useful in hyperlinks that refer to
an external file, such as an image or a copyright statement:
<img src="{@docroot}/images/logo.gif">
This is <a href="{@docRoot}/legal.html">Copyrighted</a> material.
{@docRoot} was introduced in Java 1.3.
This inline tag displays text literally,
escaping any HTML in it and ignoring any javadoc tags it may contain.
It does not retain whitespace formatting but is useful when used
within a <pre> tag.
{@literal} is available in Java 5.0 and later.
This tag is like the {@literal} tag, but displays
the literal text in code font. Equivalent
to:
<code>{@literal text}</code>
{@code} is available in Java 5.0 and later.
The {@value} tag, with no arguments, is used
inline in doc comments for static final fields and
is replaced with the constant value of that field. This tag was
introduced in Java 1.4 and is used only for constant fields.
This variant of the {@value} tag includes a
reference to a static
final field and is replaced with the constant value of that
field. Although the no-argument version of the
{@value} tag was introduced in Java 1.4, this
version is available only in Java 5.0 and later. See Section 7.3.4 for the syntax of the
reference.
The
@see tag and the inline tags
{@link}, {@linkplain} and
{@value} all encode a cross-reference to some
other source of documentation, typically to the documentation comment
for some other type or member.
reference can take three different
forms. If it begins with a quote character, it is taken to be the
name of a book or some other printed resource and is displayed as is.
If reference begins with a < character,
it is taken to be an arbitrary HTML hyperlink that uses the
<a> tag and the hyperlink is inserted into
the output documentation as is. This form of the
@see tag can insert links to other online
documents, such as a programmer's guide or
user's manual.
If reference is not a quoted string or a
hyperlink, it is expected to have the following form:
feature label
In this case, javadoc outputs the text specified
by label and encodes it as a hyperlink to
the specified feature. If
label is omitted (as it usually is),
javadoc uses the name of the specified
feature instead.
feature can refer to a
package, type, or type member, using one of the following forms:
A reference to the named
package. For example:
@see java.lang.reflect
A reference to a
class, interface, enumerated type, or annotation type specified with
its full package name. For example:
@see java.util.List
A reference to a type specified without its package name. For example:
@see List
javadoc resolves this reference by searching the
current package and the list of imported classes for a class with
this name.
A reference to a
named method or constructor within the specified type. For example:
@see java.io.InputStream#reset
@see InputStream#close
If the type is specified without its package name, it is resolved as
described for typename. This syntax is
ambiguous if the method is overloaded or the class defines a field by
the same name.
A reference to a method or constructor with the type of its
parameters explicitly specified. This is useful when
cross-referencing an overloaded method. For example:
@see InputStream#read(byte[], int, int)
A reference to a nonoverloaded method or constructor in the current
class or interface or one of the containing classes, superclasses, or
superinterfaces of the current class or interface. Use this concise
form to refer to other methods in the same class. For example:
@see #setBackgroundColor
A reference to a method or
constructor in the current class or interface or one of its
superclasses or containing classes. This form works with overloaded
methods because it lists the types of the method parameters
explicitly. For example:
@see #setPosition(int, int)
A reference to a named field within the specified class. For example:
@see java.io.BufferedInputStream#buf
If the type is specified without its package name, it is resolved as
described for typename.
A reference to a field in the
current type or one of the containing classes, superclasses, or
superinterfaces of the current type. For example:
@see #x
Documentation comments for classes,
interfaces, methods, constructors, and fields appear in Java source
code immediately before the definitions of the features they
document. javadoc can also read and display
summary documentation for packages. Since a package is defined in a
directory, not in a single file of source code,
javadoc looks for the package documentation in a
file named package.html in the directory that
contains the source code for the classes of the package.
The
package.html file should contain simple HTML
documentation for the package. It can also contain
@see, @link,
@deprecated, and @since tags.
Since package.html is not a file of Java source
code, the documentation it contains should be HTML and should
not be a Java comment (i.e., it should not be
enclosed within /** and */
characters). Finally, any @see and
@link tags that appear in
package.html must use fully qualified class
names.
In addition to defining a
package.html file for each package, you can also
provide high-level documentation for a group of packages by defining
an overview.html file in the source tree for
those packages. When javadoc is run over that
source tree, it uses overview.html as the
highest level overview it displays. | http://books.gigatux.nl/mirror/javainanutshell/0596007736/javanut5-CHP-7-SECT-3.html | CC-MAIN-2018-43 | refinedweb | 3,147 | 54.73 |
Deploying Spring Boot onto Kubernetes
Kubernetes is great, but flippin’ heck, it is unbelievably complicated for new developers.
If you’re a developer who’s new to Kubernetes, you might be staring it in the face and thinking “how the hell do I work this thing”. Or you might be thinking “oh great, yet another step in my deployment process 😩”
So I wanted to put together a clear guide on how to deploy a Spring Boot application to Kubernetes. This will get you going running your first application on Kubernetes.
Here’s what I’m going to walk through in this tutorial:
Run Kubernetes on the desktop using Minikube
Use Maven to compile a Spring Boot application to a JAR, and also build a Docker image for it
Deploy the application on Kubernetes, in a container
LET’S GO. 🎈🎈
Get yourself a friendly, local Kubernetes cluster
For a novice like me, enterprise-grade Kubernetes is pretty difficult to set up. Fortunately, for developers, there’s Minikube!
Minikube is a way to run Kubernetes on your local machine. It’s kind of like a scaled-down version of Kubernetes, which is way more suitable for doing local development work.
It lets you get a feel of Kubernetes without having to mess around doing a full install.
To set up your local Kubernetes environment with Minikube:
Go grab Minikube from here.
Then start minikube:
$ minikube start
This will start up a virtual machine (VM) and spin up a single-node Kubernetes cluster inside it.
You can check that Minikube is up and running by running
minikube status:
$ minikube status host: Running kubelet: Running apiserver: Running kubectl: Correctly Configured: pointing to minikube-vm at 192.168.99.100
At this point, Kubernetes is now running inside the virtual machine. If you want to take a look at the inner workings of Kubernetes, then you can SSH into the VM and have a look around by typing:
$ minikube ssh
When minikube starts for the first time, it will create three namespaces. Namespaces in Kubernetes are like projects within Kubernetes where we can deploy things:
$ kubectl get namespaces
We’ll deploy our Spring Boot app into the
defaultnamespace for now as it’s easiest.
Build an image with the Fabric8 Maven Plugin
The next step in the process is building a Docker image.
I prefer to get the Fabric8 Maven Plugin (FMP) to do the hard work. It’s a plugin for Maven which builds images, and does all the necessary stuff to deploy to Kubernetes or OpenShift.
FMP auto-detects your application, makes some reasonable assumptions about what you want to deploy, and sorts out the Docker build for you.
For this tutorial, I’m assuming that you’ve already got a Spring Boot application you want to deploy. (If not, go generate a new application using the Spring Initializr!)
First, we need to add the Fabric8 Maven Plugin to our project’s POM. This will set Maven up for some Fabric8 goodness.
cdto your project’s root (where your
pom.xmlis located).
Add the Fabric8 Maven Plugin into the plugin section of your
pom.xml:
<plugin> <groupId>io.fabric8</groupId> <artifactId>fabric8-maven-plugin</artifactId> <version>3.5.41</version> <configuration> <enricher> <config> <fmp-service> <type>LoadBalancer</type> </fmp-service> </config> </enricher> </configuration> <executions> <execution> <goals> <goal>resource</goal> <goal>build</goal> </goals> </execution> </executions> </plugin>
Next, build a Docker image. To build Docker images, Fabric8 Maven Plugin uses a Docker daemon.
Fortunately, Minikube already contains one!
So we execute this next command. It sets up some environment variables which configure Fabric8 Maven Plugin to use the Docker daemon running in Minikube. It does this by setting the
DOCKER_HOSTvariable, and a couple of others:
$ eval $(minikube docker-env)
If you’re running Windows, just type
minikube docker-envand it will tell you what you need to do.
Finally, we compile our Spring Boot application to a JAR (
package) and build a container image using the
fabric8:buildgoal:
$ mvn package fabric8:build
This will:
Compile your Spring Boot app to a JAR
Pull down a suitable base image to use for your application, from Docker Hub
Use Minikube’s Docker daemon to build (or bake!) a Docker image, using the base image
Push the new image into Minikube’s local Docker registry
Once the build has completed, you can take a look at it in the Docker registry:
$ docker images REPOSITORY TAG IMAGE ID CREATED SIZE apps/my-spring-boot-application latest d7e9ee334e18 About an hour ago 481MB apps/my-spring-boot-application snapshot-190303-181942-0375 d7e9ee334e18 About an hour ago 481MB
NB: Rather confusingly, each Docker image is technically listed in this command in the repository column (not to be confused with a registry, which is a place that stores and serves Docker images!)
Run the application in Kubernetes
The next thing you’ll want to do is run the application.
Fabric8 Maven Plugin can help with that too.
At its most primitive level, Kubernetes is configured by writing a bunch of YAML files and applying them to the cluster using a REST API.
It is, quite frankly, a massive faff.
Fortunately FMP can do all of the YAML stuff for you. It creates YAML files for your application and then applies them to the Kubernetes cluster.
To deploy:
$ mvn fabric8:watch
This will:
- Generate the configuration files (YAML) to be applied to Kubernetes
- Create a Deployment and a Service for your application
- Start a Pod with your application running inside a container
- Tail the logs from your Spring Boot application
Now you can visit your deployed application, in your browser.
Execute this command, which will fetch the URL to your application
$ minikube service your-application
Fabric8 Maven Plugin should still be following the logs from Spring Boot, so that you can watch them from the command line.
You can also view the application deployed in the Kubernetes Dashboard, which is a web-based view onto Kubernetes:
$ minikube dashboard
When you want to stop the application, press Ctrl+C.
This will leave the Pod running. So, finally, to undeploy the application from Kubernetes:
$ mvn fabric8:undeploy
Congrats, you’ve deployed your Spring Boot application to Kubernetes!
Any questions or comments? Post them below!
Photo by Fré Sonneveld on Unsplash
You can use Markdown in your comment. To write code, indent lines by 4 spaces. | https://tomd.xyz/articles/spring-boot-kubernetes/ | CC-MAIN-2019-39 | refinedweb | 1,062 | 60.14 |
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