and descriptors python is still best learned as progression from simple to advancedand linear reading here still makes the most sense stillsome topics may require nonlinear jumps and random lookups to minimize thesethis book will point out forward dependencies when they occurand will ease their impacts as much as possible but if your time is tightthough depth is crucial to mastering pythonsome readers may have limited time if you are interested in starting out with quick python touri suggest and (and perhaps )-- short survey that will hopefully pique your interest in the more complete story told in the rest of the bookand which most readers will need in today' python software world in generalthis book is intentionally layered this way to make its material easier to absorb--with introductions followed by detailsso you can start with overviewsand dig deeper over time you don' need to read this book all at oncebut its gradual approach is designed to help you tackle its material eventually this book' programs in generalthis book has always strived to be agnostic about both python versions and platforms it' designed to be useful to all python users neverthelessbecause python changes over time and platforms tend to differ in pragmatic waysi need to describe the specific systems you'll see in action in most examples here python versions this fifth edition of this bookand all the program examples in itare based on python versions and in additionmany of its examples run under prior and releasesand notes about the history of language changes in earlier versions are mixed in along the way for users of older pythons because this text focuses on the core languagehoweveryou can be fairly sure that most of what it has to say won' change very much in future releases of pythonas noted earlier most of this book applies to earlier python versionstooexcept when it does notnaturallyif you try using extensions added after release you're usingall bets are off as rule of thumbthe latest python is the best python if you are able to upgrade because this book focuses on the core languagemost of it also applies to both jython and ironpythonthe javaand net-based python language implementationsas well as other python implementations such as stackless and pypy (described in such alternatives differ mostly in usage detailsnot language preface xlv