1. Carl Meyer
  2. pythonv


pythonv / README

This is Python version 3.0.1

For notes specific to this release, see RELNOTES in this directory.
Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
Python Software Foundation.
All rights reserved.

Python 3 (a.k.a. "Python 3000" or "Py3k", and released as Python 3.0) is a new
version of the language, which is incompatible with the 2.x line of releases.
The language is mostly the same, but many details, especially how built-in
objects like dictionaries and strings work, have changed considerably, and a
lot of deprecated features have finally been removed.


Documentation for Python 3.0 is online, updated twice a day:


All documentation is also available online at the Python web site
(http://docs.python.org/, see below).  It is available online for occasional
reference, and it can be downloaded in many formats for faster local access.
The documentation is downloadable in HTML, PostScript, PDF, LaTeX (through
2.5), and reStructuredText (2.6, 3.0, and going forward) formats; the LaTeX
and reStructuredText versions are primarily for documentation authors,
translators, and people with special formatting requirements.

This is a work in progress; please help improve it!

The design documents for Python 3 are also online.  While the reference
documentation is being updated, the PEPs are often the best source of
information about new features.  Start by reading PEP 3000:


What's New

For an overview of what's new in Python 3.0, see Guido van Rossum's blog at


We try to eventually have a comprehensive overview of the changes in the
"What's New in Python 3.0" document, found at


Please help improve it!

For a more detailed change log, read Misc/NEWS, though this file, too, is
incomplete, and also doesn't list anything merged in from the 2.6 release.

If you want to install multiple versions of Python see the section below
entitled "Installing multiple versions".

Proposals for enhancement

If you have a proposal to change Python, you may want to send an email to the
comp.lang.python or python-ideas mailing lists for initial feedback.  A Python
Enhancement Proposal (PEP) may be submitted if your idea gains ground.  All
current PEPs, as well as guidelines for submitting a new PEP, are listed at

Converting From Python 2.x to 3.0

Python 2.6 contains features to help locating and updating code that needs to
be changed when migrating to Python 3.

A source-to-source translation tool, "2to3", can take care of the
mundane task of converting large amounts of source code.  It is not a
complete solution but is complemented by the deprecation warnings in
2.6.  This tool is currently available via the Subversion sandbox:


Installing multiple versions

On Unix and Mac systems if you intend to install multiple versions of Python
using the same installation prefix (--prefix argument to the configure script)
you must take care that your primary python executable is not overwritten by
the installation of a different version.  All files and directories installed
using "make altinstall" contain the major and minor version and can thus live
side-by-side.  "make install" also creates ${prefix}/bin/python which refers
to ${prefix}/bin/pythonX.Y.  If you intend to install multiple versions using
the same prefix you must decide which version (if any) is your "primary"
version.  Install that version using "make install".  Install all other
versions using "make altinstall".

For example, if you want to install Python 2.5, 2.6 and 3.0 with 2.6 being the
primary version, you would execute "make install" in your 2.6 build directory
and "make altinstall" in the others.

Issue Tracker and Mailing List

We're soliciting bug reports about all aspects of the language.  Fixes are
also welcome, preferable in unified diff format.  Please use the issue


If you're not sure whether you're dealing with a bug or a feature, use the
mailing list:


To subscribe to the list, use the Mailman form:


Build Instructions

On Unix, Linux, BSD, OSX, and Cygwin:

    make test
    sudo make install    # or "make altinstall"

You can pass many options to the configure script; run "./configure
--help" to find out more.  On OSX and Cygwin, the executable is called
python.exe; elsewhere it's just python.

On Mac OS X, if you have configured Python with --enable-framework,
you should use "make frameworkinstall" to do the installation.  Note
that this installs the Python executable in a place that is not
normally on your PATH, you may want to set up a symlink in

On Windows, see PCbuild/readme.txt.

If you wish, you can create a subdirectory and invoke configure from
there.  For example:

    mkdir debug
    cd debug
    ../configure --with-pydebug
    make test

(This will fail if you *also* built at the top-level directory.  You
should do a "make clean" at the toplevel first.)

Copyright and License Information

Copyright (c) 2001, 2002, 2003, 2004, 2005, 2006, 2007, 2008, 2009
Python Software Foundation.
All rights reserved.

Copyright (c) 2000 BeOpen.com.
All rights reserved.

Copyright (c) 1995-2001 Corporation for National Research Initiatives.
All rights reserved.

Copyright (c) 1991-1995 Stichting Mathematisch Centrum.
All rights reserved.

See the file "LICENSE" for information on the history of this
software, terms & conditions for usage, and a DISCLAIMER OF ALL

This Python distribution contains *no* GNU General Public License
(GPL) code, so it may be used in proprietary projects.  There are
interfaces to some GNU code but these are entirely optional.

All trademarks referenced herein are property of their respective