Python Programming/Overview

Python is a high-level, structured, open-source programming language that can be used for a wide variety of programming tasks. Python was created by Guido Van Rossum in the early 1990s; its following has grown steadily and interest has increased markedly in the last few years or so. It is named after Monty Python's Flying Circus comedy program.

Python is used extensively for system administration (many vital components of Linux distributions are written in it); also, it is a great language to teach programming to novices. NASA has used Python for its software systems and has adopted it as the standard scripting language for its Integrated Planning System. Python is also extensively used by Google to implement many components of its Web Crawler and Search Engine & Yahoo! for managing its discussion groups.

Python within itself is an interpreted programming language that is automatically compiled into bytecode before execution (the bytecode is then normally saved to disk, just as automatically, so that compilation need not happen again until and unless the source gets changed). It is also a dynamically typed language that includes (but does not require one to use) object-oriented features and constructs.

The most unusual aspect of Python is that whitespace is significant; instead of block delimiters (braces → "{}" in the C family of languages), indentation is used to indicate where blocks begin and end.

For example, the following Python code can be interactively typed at an interpreter prompt, display the famous "Hello World!" on the user screen:

 >>> print "Hello World!"
Hello World!

Another great feature of Python is its availability for all platforms. Python can run on Microsoft Windows, Macintosh and all Linux distributions with ease. This makes the programs very portable, as any program written for one platform can easily be used on another.

Python provides a powerful assortment of built-in types (e.g., lists, dictionaries and strings), a number of built-in functions, and a few constructs, mostly statements. For example, loop constructs that can iterate over items in a collection instead of being limited to a simple range of integer values. Python also comes with a powerful standard library, which includes hundreds of modules to provide routines for a wide variety of services including regular expressions and TCP/IP sessions.

Python is used and supported by a large Python Community that exists on the Internet. The mailing lists and news groups like the tutor list actively support and help new python programmers. While they discourage doing homework for you, they are quite helpful and are populated by the authors of many of the Python textbooks currently available on the market.

This book describes Python, an open-source general-purpose interpreted programming language available for the most popular operating systems. The current versions are 3.x while versions 2.x are no longer supported, since 2020. This book describes primarily the versions 3.x, but does at times reference versions 2.x.

There are a few implementations for Python 3 (and older): the standard implementation written in C, and PyPy, a JIT-compiled version written in RPython - a subset of Python. For Python 2 only there are Jython written in Java and IronPython written in C# for the .NET environment.

Contents

Intro

Basics

Advanced

Modules

Standard library modules

Third-party modules

Writing extension modules

Appendices

See also

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