optimization errors with simple jump function using glpk optimizer
hello,

i am a novice to julia programming. going though a tutorial i see myself running into this error and i am not quite sure what it means. can someone who is an expert in jump and glpk advise?

error:

methoderror: no method matching model(::type{glpk.optimizer})

code:

using interact

using pl…
for posterity, the issue was a different environment was being used in the ijulia notebook, which contained pavito, causing jump to downgrade.

for others finding this, here is the documentation on pkg environments:

[image]

[4. working with environments · pkg.jl](https://julialang.github.io/pkg.jl/v1/environments/)
method a.increment() overlaps in class b.   
 therefore, regardless of the type of the variable obj, will be called the method corresponding to the actual type of the object - that is, b.increment().  
 
this method will use the variable i, declared in the same class b and having an initial value of 10.  
 
the resulting value - 11. hmm…i wonder why it didnt

fine buddy

is it community edition or enterprise edition

if its enterprise edition of orchestrator kindly raise a ticket to technical team

[image]

[contact technical support](https://www.uipath.com/company/contact-us/contact-technical-support)

contact uipath technical support department.

cheers [@brun…](/u/bruno_silveira_uy) the compiler will throw the following errors:  


10: error: increment of read-only variable **k**,  


12: error: **lvalue** required as increment operand. that error happens when there's no handle to close. i see you call the 'open()' and you're not getting an object reference error before closehandle(). check your memory.pointerwrite() function to make sure it's not doing a closehandle() prematurely. it sounds like you're calling closehandle() twice. i suspect that the resource\_exhausted message may have originated from a back-pressuring committer node ([code](https://github.com/digital-asset/daml/blob/926fb5997a795e7f80443a9a3ba7898b1568d158/ledger/participant-integration-api/src/main/scala/platform/apiserver/services/apisubmissionservice.scala#l155-l157)). if that’s the case, i believe the approach should be the same: change the configuration if you need and make sure to handle those errors with the appropriate retry strategy. You are mixing [expressions](https://docs.microsoft.com/en-us/dotnet/api/system.linq.expressions.expression?view=netframework-4.7.1) with [lambda expressions](https://docs.microsoft.com/en-us/dotnet/api/system.linq.expressions.lambdaexpression?view=netframework-4.7.1). There are many posts showing how you can combine lambda expressions, but the essential part is to compose expressions from lambda expression [bodies](https://docs.microsoft.com/en-us/dotnet/api/system.linq.expressions.lambdaexpression.body?view=netframework-4.7.1) and rebind the [parameters](https://docs.microsoft.com/en-us/dotnet/api/system.linq.expressions.lambdaexpression.parameters?view=netframework-4.7.1).


The later is usually achieved by a custom [`ExpressionVisitor`](https://docs.microsoft.com/en-us/dotnet/api/system.linq.expressions.expressionvisitor?view=netframework-4.7.1) like this:



```
using System.Linq.Expressions;

public static class ExpressionExtensions
{
    public static Expression ReplaceParameter(this Expression expression, ParameterExpression source, Expression target)
    {
        return new ParameterReplacer { Source = source, Target = target }.Visit(expression);
    }

    class ParameterReplacer : ExpressionVisitor
    {
        public ParameterExpression Source;
        public Expression Target;
        protected override Expression VisitParameter(ParameterExpression node)
        {
            return node == Source ? Target : base.VisitParameter(node);
        }
    }
}

```

Now regarding the EF Core combined query filters. 


Using dictionaries and expression lists seems overcomplicated for what are you doing. Since [`IMutableEntityType`](https://docs.microsoft.com/en-us/dotnet/api/microsoft.entityframeworkcore.metadata.imutableentitytype?view=efcore-2.1) provides read/write access to the [`QueryFilter`](https://docs.microsoft.com/en-us/dotnet/api/microsoft.entityframeworkcore.metadata.imutableentitytype.queryfilter?view=efcore-2.1#Microsoft_EntityFrameworkCore_Metadata_IMutableEntityType_QueryFilter), the same can be achieved with a small set of a custom extension methods.


All they go inside a class like this:



```
using System;
using System.Linq.Expressions;
using Microsoft.EntityFrameworkCore.Metadata;
using Microsoft.EntityFrameworkCore.Metadata.Builders;

public static class QueryFilterExtensions
{
}

```

First method:



```
public static void AddQueryFilter(this IMutableEntityType target, LambdaExpression filter)
{
    if (target.QueryFilter == null)
        target.QueryFilter = filter;
    else
    {
        var parameter = target.QueryFilter.Parameters[0];
        var left = target.QueryFilter.Body;
        var right = filter.Body.ReplaceParameter(filter.Parameters[0], parameter);
        var body = Expression.AndAlso(left, right);
        target.QueryFilter = Expression.Lambda(body, parameter);
    }
}

```

This is a non generic method which combines the exiting filter with passed filter using `AndAlso` (C# `&&`) operator and shows the aforementioned lambda expression combining principles.


However it's not so useful directly, like inside your entity type configuration loop (it can, but requires you to build manually the lambda expression instead of letting C# compiler do that). So here comes the second method:



```
public static void AddQueryFilter<T>(this IMutableEntityType target, Expression<Func<T, bool>> filter)
{
    LambdaExpression targetFilter = filter;
    if (target.ClrType != typeof(T))
    {
        var parameter = Expression.Parameter(target.ClrType, "e");
        var body = filter.Body.ReplaceParameter(filter.Parameters[0], parameter);
        targetFilter = Expression.Lambda(body, parameter);
    }
    target.AddQueryFilter(targetFilter);
}

```

It's a generic method - not quite type-safe, but allows you to use a compile time lambda expression and bind it to the actual entity type as follows:



```
foreach (var entityType in modelBuilder.Model.GetEntityTypes())
{
    if (typeof(IDeleted).IsAssignableFrom(entityType.ClrType))
        entityType.AddQueryFilter<IDeleted>(e => e.DateTimeDeleted == null);
}

```

Looks better, isn't it :)


The last custom extension method is complement to (replacement of) the standard EF Core generic [`HasQueryFilter`](https://docs.microsoft.com/en-us/dotnet/api/microsoft.entityframeworkcore.metadata.builders.entitytypebuilder-1.hasqueryfilter?view=efcore-2.1#Microsoft_EntityFrameworkCore_Metadata_Builders_EntityTypeBuilder_1_HasQueryFilter_System_Linq_Expressions_Expression_System_Func__0_System_Boolean___) method:



```
public static EntityTypeBuilder<TEntity> AddQueryFilter<TEntity>(this EntityTypeBuilder<TEntity> target, Expression<Func<TEntity, bool>> filter)
    where TEntity : class
{
    target.Metadata.AddQueryFilter(filter);
    return target;
}

```

and allows you to replace



```
this.AddToDict<DbMyEntity>(t => t.Name == null || t.Name == "Something");

```

with the more convenient



```
modelBuilder.Entity<DbMyEntity>()
    .AddQueryFilter(t => t.Name == null || t.Name == "Something");

```

**Update (EF Core 3.0):** `QueryFilter` property has been replaced with `GetQueryFilter` and `SetQueryFilter` extension methods. What problem are you facing? Post the error that you get.  

Also please edit your first post by aligning the code properly and wrap [code] tag so that it is easily understandable for us to analyze. hey [@emartini](/u/emartini) ,

if you want to use clij2, you also need to activate the clij update site. the error should be gone then.

[[image]](https://aws1.discourse-cdn.com/business4/uploads/imagej/original/3x/0/9/095bc5fb3f3fa0db9dac6286bb16cf30ee81783d.jpeg "image")

see also the [installation instructions](https://clij.github.io/clij2-docs/installationinfiji).

let me know if this solves the issue!

cheers,

robert <http://code.djangoproject.com/wiki/CookBookNewformsAdminAndUser>


Involves implementing save methods on your ModelAdmin objects. hi marlou,  

  

as i mentioned in my response to your support ticket, this problem is already fixed in the current release - q2 2009 sp1.   

  

greetings,  

 fiko   

the telerik team

  

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