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  • Foreword for "Programming Python" (1st ed.)

    Foreword for "Programming Python" (1st ed.) Foreword for "Programming Python" (1st ed.) This is the foreword I wrote for Mark Lutz' book "Programming Python" (1st ed.), published by O'Reilly. See also my foreword to the 2nd edition. As Python's creator, I'd like to say a few words about its origins, adding a bit of personal philosophy. Over six years ago, in December 1989, I was looking for a "hobby" programming project that would keep me occupied during the we...

  • Foreword for "Programming Python" (2nd ed.)

    Foreword for "Programming Python" (2nd ed.) Foreword for "Programming Python" (2nd ed.) This is the foreword I wrote for Mark Lutz' book "Programming Python" (2nd ed.), published by O'Reilly in 2001. Less than five years ago, I wrote the foreword for the 1st edition of Programming Python. Since then, the book has changed about as much as the language and the Python community! I no longer feel the need to defend Python: the statistics and developments listed in Mark's ...

  • Python Patterns - Implementing Graphs

    Python Patterns - Implementing Graphs Warning This page stays here for historical reasons and it may contain outdated or incorrect information. Change notes: 2/22/98, 3/2/98, 12/4/00: This version of this essay fixes several bugs in the code. 6/10/19: Retraction of find_shortest_path as "nearly optimal". 8/11/19: Fix accidental usage of find_graph() instead of find_path() Copyright (c) 1998, 2000, 2003, 2019 Python Software Foundation. All rights reserved. License...

  • Metaclasses in Python 1.5

    Metaclasses in Python 1.5 Metaclasses in Python 1.5 (A.k.a. The Killer Joke :-) (Postscript: reading this essay is probably not the best way to understand the metaclass hook described here. See a message posted by Vladimir Marangozov which may give a gentler introduction to the matter. You may also want to search Deja News for messages with "metaclass" in the subject posted to comp.lang.python in July and August 1998.) In previous Python releases (and still in 1.5), there ...

  • Glue It All Together With Python

    Glue It All Together With Python Glue It All Together With Python Guido van Rossum CNRI 1895 Preston White Drive Reston, VA 20191 Email: guido@cnri.reston.va.us, guido@python.org Position paper for the OMG-DARPA-MCC Workshop on Compositional Software Architecture in Monterey, California, January 6-8, 1998. Introduction Python is an advanced scripting language that is being used successfully to glue together large software components. It spans multiple platforms, mid...

  • Built-in Package Support in Python 1.5

    Built-in Package Support in Python 1.5 Built-in Package Support in Python 1.5 Starting with Python version 1.5a4, package support is built into the Python interpreter. This implements a slightly simplified and modified version of the package import semantics pioneered by the "ni" module. "Package import" is a method to structure Python's module namespace by using "dotted module names". For example, the module name A.B designates a submodule named B in a package named A. Just like...

  • Parade of the PEPs

    Parade of the PEPs Parade of the PEPs To start off Developer's Day at the Python10 conference I gave a keynote ending in what I dubbed "the parade of the PEPs". It was a brief overview of all open PEPs, where I gave my highly personal and subjective opinion for each PEP. Later, I realized that this might have been of interest to other developers. I didn't take notes at the conference, so below is a different set of comments that I created from scratch during a single two-hour sitt...

  • Debugging Reference Count Problems

    Debugging Reference Count Problems Warning This page stays here for historical reasons and it may contain outdated or incorrect information. Debugging Reference Count Problems From: Guido van Rossum <guido@CNRI.Reston.VA.US> To: python-list@cwi.nl Date: Wed, 27 May 1998 11:09:40 -0400 Mike Fletcher wrote a number of posts about debugging C code that bombs, probably because of reference count problems. His approach to debugging this problem seems typical, but I thin...

  • Standard Exception Classes in Python 1.5

    Standard Exception Classes in Python 1.5 Standard Exception Classes in Python 1.5 (updated for Python 1.5.2 -baw) User-defined Python exceptions can be either strings or Python classes. Since classes have many nice properties when used as exceptions, it is desirable to migrate to a situation where classes are used exclusively. Prior to Python 1.5 alpha 4, Python's standard exceptions (IOError, TypeError, etc.) were defined as strings. Changing these to classes posed some particula...

  • Python Style Guide

    Python Style Guide Python Style Guide Author: Guido van Rossum The style guide originally at this URL has been turned into two PEPs (Python Enhancement Proposals): PEP 8 for the main text, and PEP 257 for docstring conventions.

  • Python Humor

    Python Humor Here is a spurious collection of semi to totally unserious stuff, mostly postings found wafting gently in the comp.lang.python newsgroup (a.k.a. the python-list mailing list). See also Andrew Kuchling's collection of Python quotations, containing in a condensed form some sterling examples of the wit and wisdom encountered in the Python world. Contents The Zen of Python Fundamental... Cute Wabbit Shooting Yourself in the Foot Legal Issues Python vs Tcl vs Perl5 Python Object Orie...

  • New-style Classes

    New-style Classes Warning New-style classes has been integrated into Python 2.7 and old-style classes has been removed in Python 3. Please refer to the Python tutorial and the Descriptor HowTo Guide for more up-to-date documentation about classes and descriptors respectively. Unfortunately, new-style classes have not yet been integrated into Python's standard documentation. Fear not, however; many people have worked to provide useful information on creating and using new-style classes: Unif...

  • Slideshow Collections for Instructional Use

    Slideshow Collections for Instructional Use We are collecting and making available slideshows for reading at your own pace and reuse in your presentations. The preferred format is reStructuredText/S5 since it can be easily edited without special software and converted into various delivery formats. Where possible, speaker notes are included to give the slides meaning without an audio overlay. Preparing for Screencasting Advice on how to get started giving screencasts, why you might want to...

  • Python documentation by version

    Python documentation by version Some previous versions of the documentation remain available online. Use the list below to select a version to view. For unreleased (in development) documentation, see In development versions. Python 3.14.0, documentation released on 7 October 2025. Python 3.13.9, documentation released on 14 October 2025. Python 3.13.8, documentation released on 7 October 2025. Python 3.13.7, documentation released on 14 August 2025. Python 3.13.6, documentation released on 6...

  • Python for Mac OS X

    Python for Mac OS X Python for Mac OS X Python comes pre-installed on Mac OS X so it is easy to start using. However, to take advantage of the latest versions of Python, you will need to download and install newer versions alongside the system ones. The easiest way to do that is to install one of the binary installers for OS X from the Python Download page. Installers are available for the latest Python 3 and Python 2 releases that will work on all Macs that run Mac OS X 10.5 and later. Py...

  • Download Python for other platforms

    Download Python for other platforms Python has been ported to a number of specialized and/or older platforms, listed below in alphabetical order. Note that these ports often lag well behind the latest Python release. Python for AIX AIX binary packages for Python are available from IBM AIX Toolbox in RPM format. They can be installed using dnf package manager. Visit the Get Started page for more details. Python for HP-UX You can purchase ActivePython (commercial and community versions, in...

  • Releases

    Releases Python releases are now listed on the downloads page. This page only provides links to older releases which are not listed in the release database. Python 1.6.1 (September 2000) Python 1.5.2 (April 1999) Older source releases (1.0.1 - 1.6) Ancient source releases (pre 1.0) Python 1.5 binaries Python 1.4 binaries Python 1.3 binaries Python 1.2 binaries Python 1.1 binaries

  • Python 1.5.2

    Python 1.5.2 Python 1.5.2 Do yourself a favor and get a more recent version! On 13 April 1999, the final version of Python 1.5.2 was released: Python 1.5.2 sources (2.5 MB) Python 1.5.2 installer for Windows (5.0 MB) What's new in 1.5.2? Documentation (both online and downloadable) Note: the Python installer for Windows includes the Tcl/Tk 8.0.5 installer. See the Tkinter resource guide for troubleshooting the Tcl/Tk installation. Windows users may also be interested in Mark Hammond's win...

  • What's new in Python 1.5 and beyond

    What's new in Python 1.5 and beyond If you download the source release, there's a loooong list of changes since release 1.4 in the file Misc/NEWS. Below are some highlights. (Or go directly to the listings of what's new in 1.5b1, what's new in 1.5b2, and what's new in 1.5 (final).) For an essay on the (difficult!) subject of metaprogramming, see my essay Metaprogramming in Python 1.5. See also the description of some major new features in version 1.5: Built-in Package Support and Stand...

  • Python 1.6

    Python 1.6 Python 1.6 Note: See the download pages for more recent releases. The final version of Python 1.6 is released on September 5, 2000. (What's new?) CNRI has placed an open source license on this version. CNRI believes that this version is compatible with the GPL, but there is a technicality concerning the choice of law provision, which Richard Stallman believes may make it incompatible. CNRI is still trying to work this out with Stallman. Future versions of Python ...

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