TableOfContents

Python语言介绍

1. 总览

Python是一种解释型的编程语言，由Guido van Rossum于1990年创造。Python是完全动态类型的语言，使用自动的内存管理；在这方面它和Perl、Ruby、Scheme、Smalltalk和Tcl语言是类似的。Python是由开放源代码项目开发，由非盈利性组织Python软件基金会（Python Software Foundation）管理，并在项目网站上免费开放。Python 2.4.3版于2006年3月29日发布。

2. Python设计哲学

Python是一种多范式的语言。也就是说，它不强制编程人员采用某一种特定的编程范式，而是允许多种范式。对于面向对象程序设计（OOP）、结构化程序设计、函数式程序设计（FP）以及面向侧面的程序设计（AOP），它都可以支持。其它的编程模式也可以通过一些扩展来支持，比如通过pyDBC和Contracts for Python可以支持契约式设计（Design by Contract）。Python使用动态类型检查，并使用垃圾收集来进行内存管理。Python一个重要的特性是动态名字解析，即它会在运行时对方法和变量名进行绑定。

在提供多种编程方法的选择的同时，Python的设计者拒绝像Perl那样使用过多过杂乱的语法，而是采用了少而清晰的语法。和Perl一样，Python的开发人员明确的提炼出一种特别的"文化"或者观念，这种文化或观念来自于他们对于语言的期望，这种文化带来一种他们认为是"漂亮"、"明确"和"简单"的语言形式。Perl用户和Python用户最大的区别在于他们对于这些词语的解释不同，以及它们如何被最好的实现（参见TIMTOWTDI和Python哲学）。

Another important goal of the Python developers is making Python fun to use. This is reflected in the origin of the name (after the television series Monty Python's Flying Circus), in the common practice of using Monty Python references in example code, and in an occasionally playful approach to tutorials and reference materials. For example, the metasyntactic variables often used in Python literature are spam and eggs, instead of the traditional foo and bar.

Python开发人员另一个重要的目标是让Python用起来尽量有趣。这反映在Python的名字的由来上（由Monty Python的飞行马戏团的系列电视节目命名），也反映在示例代码中使用Monty Python上，也反映在入门和参考材料中偶尔出现的玩笑式的方法上。比如说，在解释有关语法没有实际含义的变量名字上，Python经常使用spam和eggs，而不是传统的foo和bar。

Python is sometimes referred to as a "scripting language". In practice, it is used as a dynamic programming language for both application development and occasional scripting. Python has been used to develop many large software projects such as the Zope application server and the Mnet and BitTorrent file sharing systems. It is also extensively used by Google.

Python有时候被称作"脚本语言"。实际上，作为一种动态的编程语言，它既用于应用开发，偶尔也用于脚本开发。Python已经被用于开发很多大型的软件项目，比如说Zope应用服务器，和Mnet、BitTorrent文件共享系统。它也被Google广泛使用。

Another important goal of the language is ease of extensibility. New built-in modules are easily written in C or C++. Python can also be used as an extension language for existing modules and applications that need a programmable interface.

这个语言的另一个重要目标是易扩展性。新的内置模块可以很容易用C或者C++写成。对于现有的需要一个可编程接口的模块或者应用程序，Python也可以作为它们的一个扩展语言来使用。

Though the design of Python is somewhat hostile to functional programming (no tail call elimination or good support for anonymous closures) and the Lisp tradition, there are significant parallels between the philosophy of Python and that of minimalist Lisp-family languages such as Scheme. Many past Lisp programmers have found Python appealing for this reason.

虽然Python的设计时有些反对函数式编程（没有尾递归消除和好的匿名closure的支持）和Lisp习惯，但是Python的哲学和一些Lisp家族的最小化语言（比如Scheme）的哲学有很多重要的类似之处。很多曾经的Lisp程序员发现Python在这方面是很有吸引力的。

The Zen of Python by TimPeters: Python之道：

1. Beautiful is better than ugly. 美比丑好。
2. Explicit is better than implicit. 直言不讳比心照不宣好。
3. Simple is better than complex. 简单比内部复杂更好。
4. Complex is better than complicated. 内部复杂比外部复杂好。
5. Flat is better than nested. 平面的比嵌套的好
6. Sparse is better than dense. 错落有致比密密匝匝的好
7. Readability counts. 可读性很重要
8. Special cases aren't special enough to break the rules. 特殊情况不能特殊到打破规律
9. Although practicality beats purity. 虽然实用比纯粹更重要
10. Errors should never pass silently. 永远别让错误悄悄地溜走
11. Unless explicitly silenced. 除非是你故意的
12. In the face of ambiguity, refuse the temptation to guess. 碰到模棱两可的地方，绝对不要去作猜测
13. There should be one-- and preferably only one --obvious way to do it. 什么事情都应该有一个，而且最好只有一个显而易见的解决办法
14. Although that way may not be obvious at first unless you're Dutch. 虽然刚开始的时候，这个办法可能不是那么的显而易见，但谁叫你不是荷兰人
15. Now is better than never. 现在就开始要比永远都不做要好。
16. Although never is often better than ＊right＊ now. 虽然很多时候永远都不做要比匆匆忙忙去做要好。
17. If the implementation is hard to explain, it's a bad idea. 如果一个想法实现起来很困难，那它本身就不是一个好想法
18. If the implementation is easy to explain, it may be a good idea. 如果一个想法实现起来很容易，那它或许就是一个好想法

19. NameSpaces are one honking great idea -- let's do more of those! 名字空间是个了不起的想法，所以我们现在就开始吧

If you have Python 2.1.2 or later you can read the Philosophy of Python whenever you want. Just do the following:

如果你使用2.1.2版或者更新的Python，你在任何时候都可以使用如下命令来阅读Python的哲学：

 $ python
 Python 2.2 (#1, Apr 17 2002, 16:11:12) 
 [GCC 2.95.2 19991024 (release)] on some-os
 Type "help", "copyright", "credits" or "license" for more information.
 >>> import this

3. duck typing 鸭子类型

In computer science, duck typing is a term for dynamic typing typical of some programming languages, such as Smalltalk or Visual FoxPro, where a variable's value itself determines what the variable can do. It also implies that an object is interchangeable with any other object that implements the same interface, regardless of whether the objects have a related inheritance hierarchy.

在计算机科学中，鸭子类型是一个描述某些语言（比如Smalltalk、Visual Foxpro等）中的动态类型系统的名词。在这些语言中，变量的值决定了这个变量能够做什么。这意味着，一个对象和其它任何一个实现同样接口的对象都是可以互换的，而不管这些对象是不是有继承关系。

The term is a reference to the "duck test"—"If it walks like a duck and quacks like a duck, it must be a duck." One can also say that the duck typing method ducks the issue of typing variables.

这个名词源自"鸭子测试"："如果一个东西像鸭子一样走路，像鸭子一样叫，那么它一定就是鸭子。"One can also say that the duck typing method ducks the issue of typing variables.

Pythonic programming style that determines an object's type by inspection of its method or attribute signature rather than by explicit relationship to some type object ("If it looks like a duck and quacks like a duck, it must be a duck.") By emphasizing interfaces rather than specific types, well-designed code improves its flexibility by allowing polymorphic substitution. Duck-typing avoids tests using type() or isinstance(). Instead, it typically employs hasattr() tests or EAFP [Easier to Ask Forgiveness than Permission] programming.

Pythonic编程风格，通过观查一个对象的方法或属性特征，而不是一个对象和某种类型的显式关系来决定一个对象的类型（"如果一个东西像鸭子一样走路，像鸭子一样叫，那么它一定就是鸭子。"）。通过注重接口而不是某种类型，良好设计的代码通过多态来提高了灵活性。鸭子类型避免使用type()和isinstance()。取而代之的是，它使用hasattr()来测试或者EAFP（Easier to Ask Forgiveness than Permission）编程。

The standard example of duck typing in Python is file-like classes. Classes can implement some or all of the methods of file and can be used where file would normally be used. For example, GzipFile implements a file-like object for accessing gzip-compressed data. cStringIO allows treating a Python string as a file. Sockets and files share many of the same methods as well. However, sockets lack the tell() method and cannot be used everywhere that GzipFile can be used. This shows the flexibility of duck typing: a file-like object can implement only methods it is able to, and consequently it can be only used in situations where it makes sense.

Python中鸭子类型的标准例子是类似file的类。类可以实现一部分或者全部file的方法，然后可以用在file原来可以使用的地方。比如说，GzipFile实现了类似file的对象来访问gzip压缩的数据。cStringIO允许将一个Python字符串作为文件来处理。Sockets和files也有很多相同的方法。然而，socket缺少tell()，不能要在任何GzipFile可以使用的地方。这说明鸭子类型的一个灵活性：一个类似file的对象可以只实现它能够实现的方法，这使它只能够用在合理的地方。

4. 新名词Pythonic

A few neologisms have come into common use within the Python community. One of the most common is "pythonic", which can have a wide range of meanings related to program style. To say that a piece of code is pythonic is to say that it uses Python idioms well; that it is natural or shows fluency in the language. Likewise, to say of an interface or language feature that it is pythonic is to say that it works well with Python idioms; that its use meshes well with the rest of the language.

In contrast, a mark of unpythonic code is that it attempts to "write C++ (or Lisp, or Perl) code in Python"—that is, provides a rough transcription rather than an idiomatic translation of forms from another language.

The prefix Py- can be used to show that something is related to Python. Examples of the use of this prefix in names of Python applications or libraries include Pygame, a binding of SDL to Python (commonly used to create games), PyUI, a GUI encoded entirely in Python, and PySol, a series of solitaire card games programmed in Python.

Users and admirers of Python—most especially those considered knowledgeable or experienced—are often referred to as Pythonists, Pythonistas, and Pythoneers

5. 历史

5.1. Python 1

Python was created in the early 1990s by Guido van Rossum at CWI in the Netherlands as a successor of the ABC programming language. van Rossum is Python's principal author, and his continuing central role in deciding the direction of Python is jokingly acknowledged by referring to him as its Benevolent Dictator for Life (BDFL).

The last version released from CWI was Python 1.2. In 1995, Guido continued his work on Python at the Corporation for National Research Initiatives (CNRI) in Reston, Virginia where he released several versions of the software. Python 1.6 was the last of the versions released by CNRI.

Following the release of Python 1.6, and after Guido van Rossum left CNRI to work with commercial software developers, it became clear that the ability to use Python with software available under the GPL was very desirable. CNRI and the Free Software Foundation (FSF) interacted to develop enabling wording changes to the Python's free software license that would make it GPL-compatible. That year, Guido was awarded the FSF Award for the Advancement of Free Software.

Python 1.6.1 is essentially the same as Python 1.6, with a few minor bug fixes, and with the new GPL-compatible license.

5.2. Python 2

In 2000, Guido and the Python core development team moved to BeOpen.com to form the BeOpen PythonLabs team. Python 2.0 was the first and only release from BeOpen.com. After Python 2.0 was released by BeOpen.com, Guido van Rossum and the other PythonLabs developers joined Digital Creations.

Python 2.1 was a derivative work of Python 1.6.1, as well as of Python 2.0. Its license was renamed Python Software Foundation License. All intellectual property added, from the time of Python 2.1's alpha release on, is owned by the Python Software Foundation (PSF), a non-profit organization modeled after the Apache Software Foundation.

5.3. 未来

Python developers have an ongoing discussion of a future version called Python 3.0 (the project is called "Python 3000" or "Py3K") that will break backwards compatibility with the 2.x series in order to repair perceived flaws in the language. The guiding principle is to "reduce feature duplication by removing old ways of doing things". There is no definite schedule for Python 3.0, but a PEP (Python Enhancement Proposal) that details planned changes exists. [2]

Planned changes include:

• move map, filter and reduce out of the built-in namespace (the rationale being that map and filter are expressed more clearly as list comprehensions, and reduce more clearly as an accumulation loop)
• add support for optional type declarations
• unify the str/unicode types, and introduce a separate mutable bytes type
• convert built-ins to returning iterators (instead of lists), where appropriate
• remove backwards-compatibily features like classic classes, classic division, string exceptions, implicit relative imports

6. Python语法特点

Python was designed to be a highly readable language. It aims toward an uncluttered visual layout, uses English keywords frequently where other languages use punctuation, and has notably fewer syntactic constructions than many structured languages such as C, Perl, or Pascal.

Python被设计成具有高度可读性的语言。他的目标是整齐的视觉布局，更多的使用英语单词来代替其他语言中的标点符号，比其他结构化语言（比如C、Perl或者Pascal）少得多的语法结构。

6.1. Indentation 缩进

Python uses indentation, rather than curly braces, to delimit blocks. An increase in indentation comes after certain statements; a decrease in indentation signifies the end of the current block.

Python使用缩进而不是一对花括号来划分语句块。在一些特定的语句后面的语句上增加缩进量（表示语句块的开始）；用减少缩进量来表示当前语句块的结束。

6.2. Statements 语句

Python's statements include: Python的语句包括：

• if statement, for conditionally executing blocks of code, along with else and elif (a contraction of else-if). if语句和else、elif（else-if的缩写）一起，依照一定的条件执行一些语句块。
• The while statement runs a block of code until a condition is False. while语句反复执行一个语句块，直到条件变成False
• for loops iterate over an iterable, capturing each element to a local variable for use by the attached block. for循环语句跌代一个可跌代的东西，取出其中每一个元素赋给一个局部变量，这个变量在该语句附属的语句块中可以使用。
• class statements execute a block of code and attach its local namespace to a class, for use in object oriented programming. class语句执行一个语句块，并把一个局部名字空间和一个类绑定在一起。它用在面向对象编程上。
• def defines a function. def语句定义一个函数

Each statement has its own semantics: for example, the def statement does not execute its block immediately, unlike most other statements. 每个语句都有它自己的语义：比如说，def语句和其他很多语句不通，它不会马上执行它附属的语句块，

6.3. Fundamental datatypes 基本数据类型

Python includes a number of different datatypes. Amongst the most used are: Python包括一组不同的数据类型。其中最常用的是：

• list — a mutable sequence. 一个可变的顺序容器。
• str — an immutable sequence of characters. 一个不可变的由字符构成的顺序容器。
• dict — a dictionary. 一个字典
• set — an approximation of a mathematical set (an unordered collection, where each element can only appear once). 和数学上的集合差不多的东西（无序的容器，每个元素只出现一次）。

This list is not exhaustive; there are many other types provided by Python - these are merely some of the most commonly used.

这里并没有列出全部类型，Python中还有很多其他类型。而以上这些是最常用的部分。

7. Python支持的平台

The most popular (and therefore best maintained) platforms Python runs on are Linux, BSD, Mac OS X, Microsoft Windows. Separate implementations also exist for the Java (called Jython) and for the .NET Framework or Mono (called IronPython). Other supported platforms include:

运行Python最流行的平台（也是维护的最好的）是Linux、BSD、Mac OS X和Microsoft Windows。Java平台上和.Net Framework(或者Mono)上也存在一些Python的实现，分别称作Jython和IronPython。其他支持的平台包括：

Unix-like 类Unix

• AIX operating system
• BSD
• FreeBSD
• NetBSD
• Linux
• OpenBSD
• SPARC Solaris
• Other Unixes, e.g. Irix

Desktop OS's 桌面操作系统

• Amiga
• AROS
• BeOS
• Mac OS 9
• Mac OS X
• Microsoft Windows
• OS/2
• RISC OS (formerly Acorn)

Special and embedded 特殊的和嵌入式的

• GP2X
• Java virtual machine
• Nokia 770 Internet Tablet
• Palm OS

• PlayStation 2

• PlayStation Portable

• Psion
• QNX
• Sharp Zaurus
• Symbian OS
• Windows CE/Pocket PC
• Xbox (Used in XBMC)

• VxWorks

Mainframe and other 大型机和其他的

• AS/400
• OS/390
• Plan 9 from Bell Labs
• VMS
• z/OS

Most of the third-party libraries for Python (and even some first-party ones) are only available on Windows, Linux, BSD, and Mac OS X.

Python的大部分第三方库（甚至部分官方库）只支持Windows、Linux、BSD和Mac OS X。

Python was originally developed as a scripting language for the Amoeba operating system capable of making system calls; however, that version is no longer maintained.

Python最早是作为Amoeba操作系统上一种能够进行系统调用的脚本语言开发的；然而那个版本现在不再维护了。

8. Python应用领域

Python is used in a wide variety of application domains, including web and internet, database, desktop GUIs, scientific and numeric computation, education, network programming, software build and testing, and game development and 3D rendering, among others.

8.1. Web and Internet Development

Python offers a wide range of choices for web development including high-end solutions such as Zope, mega frameworks such as Django and TurboGears, and advanced content management systems such as Plone and CPS. Python is also great for CGI.

Python's extensive support for XML, email, RSS feeds, and many other Internet protocols makes Python a great choice for developing custom web solutions and other internet-based applications.

8.2. Database Access

Need to access a database? Custom and ODBC interfaces to MySQL, Oracle, MS SQL Server, PostgreSQL, SybODBC, and others are available for free download.

8.3. Desktop GUIs

Python arrives on your hard drive with the Tk GUI development library. Third-party libraries are available for MFC (via win32 extensions), wxWidgets, GTK, Qt, Delphi, and more. Scientific and Numeric

Python is widely used in scientific and numeric computing, including in Bioinformatics (see also Python course in Bioinformatics) and Physics, among others.

8.4. Education

Python is a superb language for teaching programming, both at the introductory level and for more advanced courses. The Education Special Interest Group is a good place to start. See also pyBiblio and the Software Carpentry Course (funded by the Python Software Foundation).

8.5. Network Programming

In addition to web and internet support described above, Python also provides support for lower level network programming with its easy to use sockets implementation and with powerful third party modules such as Twisted, a framework for asyncronous network programming,

8.6. Software Development

Python is often used as a support language for software developers, for build control and management, testing, and in many other ways. Some of the development support tools written in Python include SCons for build control, Buildbot and Apache Gump for automated continuous compilation and testing, and Trac for bug tracking and project management.

See also the list of Integrated Development Environments available for Python and the Python Package Index, which hosts thousands of third party modules for Python.

8.7. Game and 3D Graphics

Python is widely used in commercial and hobby game development (some of which are listed on the Python Games wiki page). PyGame and PyKyra are two of the game frameworks available for Python. There are also a number of 3D rendering libraries available for Python.

9. Python应用

The Python programming language is actively used in industry and academia for a wide variety of purposes.

9.1. Python的教育用途

As of 2005, Python is getting more popular for teaching computer programming. Its strengths for teaching include its syntactic simplicity, flexible typing, and interactive interpreter.

Python uses far fewer symbols than languages like Java and C. For example blocks inside loops and IF statements are indicated by indentation rather than curly braces ({}), and the end of a line does not have to have a semicolon. Beginning students often have initial trouble with memorizing where curly braces and semi-colons go. With Python students can skip directly to the fun part of writing code that does something. Similarly, with Java, and C++, variables types must be declared before being used. That is not needed in Python which again allows students to quickly get to the interesting part of getting their program to do something.

The interactive interpreter is an extremely valuable aid to learning and experimentation. Learning-by-doing is about trying things out and seeing what happens. The faster you can get results from your experiment, the faster that learning produces results. Experience has shown that the interactive interpreter and lack of a compiler really speeds up the learning process, both for beginners and for pros who are learning a new library and such.

9.2. 使用Python的大型组织

• Google uses Python for many tasks including the backends of web apps such as Gmail and Google Maps and for many of its search-engine internals.
• NASA is using Python to implement a CAD/CAE/PDM repository and model management, integration, and transformation system which will be the core infrastructure for its next generation collaborative engineering environment.

9.3. 使用Python写成的软件

• BitTorrent, the original implementation and several derivatives

• Chandler, a personal information manager including calendar, email, tasks and notes support that is currently under development
• Civilization IV videogame and the newly released computer game uses boost.python to allow the Python programming language access to many parts of the game (including the style and content of all interface screens)
• Mailman, one of the more popular packages for running email mailing lists
• Kombilo, go games' database manager and browser.

• MoinMoin, a popular wiki engine in Python

• OpenRPG, a virtual table on which to play Role Playing Games over the internet
• Plone, a user-friendly and powerful open source Content Management System
• Portage, the heart of Gentoo Linux. An advanced package management system based on the *BSD style ports system
• Solipsis, a system for massively shared virtual world

• Trac, bug/issue tracking database, integrated with MoinMoin wiki and Subversion source version control

• Turbogears, an application framework composed of Cherrypy, SQLObject, MochiKit, and KID templates

• Vampire: The Masquerade - Bloodlines, a videogame, uses Python for game scripting
• ViewVC, a web-based interface for browsing CVS and SVN repositories
• Zope, an object-oriented web-application platform. Zope includes an application server with an integrated object-oriented database and a built-in web-based management interface
• Battlefield 2, a first person shooter that uses python for its configuration scripts
• Indian Ocean Tsunami Detector, a free mobile phone software for tsunami prediction.
• EVE Online, a space Multi Massive Online Role Playing Game, the highest-ranked MMORPG on MMORPG.com

• SPE - Stani's Python Editor, a free, open-source Python IDE for Windows, Linux & Mac with wxGlade (GUI designer), PyChecker (Code Doctor) and Blender (3D) support.

9.4. Python包

The Python Cheese Shop and Vaults of Parnassus are two primary directories of hundreds of Python packages

• matplotlib, an extension providing matlab-like plotting and mathematical functions
• Numeric Python, a language extension that adds support for large, multi-dimensional arrays and matrices

• SciPy, a library of scientific and numerical routines

• SimPy, a discrete-event simulation package;

• Biopython, an international association of developers of freely available Python tools for computational molecular biology.
• PyOpenGL, a package that allows 3D rendering using Python
• Soya 3D, a high-level 3D game engine for Python

• Pygame http://www.pygame.org Python game development

• Python Imaging Library, a module for working with images

• PyGTK, http://www.pygtk.org/, a popular cross-platform GUI library based on GTK+; furthermore, other GNOME libraries also have bindings for Python

• PyQt, another popular cross-platform GUI library based on Qt; as above, KDE libraries have bindings too

• wxPython, a port of wxWidgets and a popular cross-platform GUI library for Python
• PyObjC, a Python-Objective C bridge that allows one to write Mac OS X software in Python
• py2exe, compiler that turns Python scripts into standalone Windows programs

• CherryPy, a Python-powered web framework

• Django, another Python-powered web framework
• Topsite Templating System, another Python-powered web framework

• TurboGears, a web framework combining CherryPy, SQLObject, and Kid

• ZODB a Python-specific object-oriented database
• Cheetah, a Python-powered template engine and code-generation tool
• mod_python, an Apache module allowing direct integration of Python scripts with the Apache web server
• Quixote (software) a framework for developing Web applications in Python
• Twisted, a networking framework for Python

See more recommended modules at Useful Modules in the Python.org wiki.

9.5. 软件目录

• Python Cheese Shop (also called the Python Package Index or PyPI) is the official directory of Python software libraries and modules.

• ActiveState O'Reilly Python Cookbook contains hunderds of code samples for various tasks using Python.

• Python Projects and Modules lots of useful code, as well as several articles on Python Programming.
• Vaults of Parnassus — Links to resources.
• Python 3D Software Collection — pointers to packages specifically useful in the production of 3D software and/or games with Python

10. Python的实现

The standard Python interpreter also supports an interactive mode in which it acts as a kind of shell: expressions can be entered one at a time, and the result of their evaluation is seen immediately. This is a boon for those learning the language and experienced developers alike: snippets of code can be tested in interactive mode before integrating them into a proper program. As well, the Python shell is often used to interactively perform system tasks, such as modifying files.

Python also includes a unit testing framework for creating exhaustive test suites. While static typing aficionados see this as a replacement for a static type-checking system, Python programmers largely do not share this view.

Standard Python does not support continuations, and according to Guido van Rossum, never will. However, better support for coroutine-like functionality is planned, by extending Python's generators [3]

• Python – The reference implementation, also known as CPython
• Jython – Python coded in Java

• IronPython – Python for .NET and Mono platforms

• Boo – Python-based but with static typing, for .NET and Mono
• Stackless Python - Python with coroutines
• Psyco - not an implementation, but JIT compiler for CPython

• PyPy – Python coded in Python

• Parrot – Virtual machine being developed mainly as the runtime for Perl 6, but with the intent to also support dynamic languages like Python, Ruby, Tcl, etc. Can currently execute a subset of Python
• Logix – Python alternate front-end with macros
• Movable Python- An alternative distribution of CPython for Windows. It can run off a USB stick and provides a Portable Programming Environment.

11. Python的标准库

Python has a large standard library, which makes it well suited to many tasks. This comes from a so-called "batteries included" philosophy for Python modules. The modules of the standard library can be augmented with custom modules written in either C or Python. The standard library is particularly well tailored to writing Internet-facing applications, with a large number of standard formats and protocols (such as MIME and HTTP) supported. Modules for creating graphical user interfaces, connecting to relational databases, arithmetic with arbitrarily precise decimals, and manipulating regular expressions are also included.

The standard library is one of Python's greatest strengths. The bulk of it is cross-platform compatible, meaning that even heavily leveraged Python programs can often run on Unix, Windows, Macintosh, and other platforms without change.

It is currently being debated whether or not third-party but open source Python modules such as Twisted, NumPy, or wxPython should be included in the standard library, in accordance with the batteries included philosophy.