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Python Enhancement Proposals

PEP 283 – Python 2.3 Release Schedule

Guido van Rossum

Table of Contents


This document describes the development and release schedule for Python 2.3. The schedule primarily concerns itself with PEP-sized items. Small features may be added up to and including the first beta release. Bugs may be fixed until the final release.

There will be at least two alpha releases, two beta releases, and one release candidate. Alpha and beta releases will be spaced at least 4 weeks apart (except if an emergency release must be made to correct a blunder in the previous release; then the blunder release does not count). Release candidates will be spaced at least one week apart (excepting again blunder corrections).

alpha 1 31 Dec 2002
alpha 2 19 Feb 2003
beta 1 25 Apr 2003
beta 2 29 Jun 2003
candidate 1 18 Jul 2003
candidate 2 24 Jul 2003
final 29 Jul 2003

Release Manager

Barry Warsaw, Jeremy Hylton, Tim Peters

Completed features for 2.3

This list is not complete. See Doc/whatsnew/whatsnew23.tex in CVS for more, and of course Misc/NEWS for the full list.

  • Tk 8.4 update.
  • The bool type and its constants, True and False (PEP 285).
  • PyMalloc was greatly enhanced and is enabled by default.
  • Universal newline support (PEP 278).
  • PEP 263 Defining Python Source Code Encodings, Lemburg

    Implemented (at least phase 1, which is all that’s planned for 2.3).

  • Extended slice notation for all built-in sequences. The patch by Michael Hudson is now all checked in.
  • Speed up list iterations by filling tp_iter and other tweaks. See; also done for xrange and tuples.
  • Timeout sockets.
  • Stage B0 of the int/long integration (PEP 237). This means issuing a FutureWarning about situations where hex or oct conversions or left shifts returns a different value for an int than for a long with the same value. The semantics do not change in Python 2.3; that will happen in Python 2.4.
  • Nuke SET_LINENO from all code objects (providing a different way to set debugger breakpoints). This can boost pystone by >5%., now checked in. (Unfortunately the pystone boost didn’t happen. What happened?)
  • Write a pymemcompat.h that people can bundle with their extensions and then use the 2.3 memory interface with all Pythons in the range 1.5.2 to 2.3. (Michael Hudson checked in Misc/pymemcompat.h.)
  • Add a new concept, “pending deprecation”, with associated warning PendingDeprecationWarning. This warning is normally suppressed, but can be enabled by a suitable -W option. Only a few things use this at this time.
  • Warn when an extension type’s tp_compare returns anything except -1, 0 or 1.
  • Warn for assignment to None (in various forms).
  • PEP 218 Adding a Built-In Set Object Type, Wilson

    Alex Martelli contributed a new version of Greg Wilson’s prototype, and I’ve reworked that quite a bit. It’s in the standard library now as the module sets, although some details may still change until the first beta release. (There are no plans to make this a built-in type, for now.)

  • PEP 293 Codec error handling callbacks, Dörwald

    Fully implemented. Error handling in unicode.encode or str.decode can now be customized.

  • PEP 282 A Logging System, Mick

    Vinay Sajip’s implementation has been packagized and imported. (Documentation and unit tests still pending.)

  • A modified MRO (Method Resolution Order) algorithm. Consensus is that we should adopt C3. Samuele Pedroni has contributed a draft implementation in C, see This has now been checked in.
  • A new command line option parser. Greg Ward’s Optik package ( has been adopted, converted to a single module named optparse. See also
  • A standard datetime type. This started as a wiki: A prototype was coded in nondist/sandbox/datetime/. Tim Peters has finished the C implementation and checked it in.
  • PEP 273 Import Modules from Zip Archives, Ahlstrom

    Implemented as a part of the PEP 302 implementation work.

  • PEP 302 New Import Hooks, JvR

    Implemented (though the 2.3a1 release contained some bugs that have been fixed post-release).

  • A new pickling protocol. See PEP 307.
  • PEP 305 (CSV File API, by Skip Montanaro et al.) is in; this is the csv module.
  • Raymond Hettinger’s itertools module is in.
  • PEP 311 (Simplified GIL Acquisition for Extensions, by Mark Hammond) has been included in beta 1.
  • Two new PyArg_Parse*() format codes, ‘k’ returns an unsigned C long int that receives the lower LONG_BIT bits of the Python argument, truncating without range checking. ‘K’ returns an unsigned C long long int that receives the lower LONG_LONG_BIT bits, truncating without range checking. (SF 595026; Thomas Heller did this work.)
  • A new version of IDLE was imported from the IDLEfork project ( The code now lives in the idlelib package in the standard library and the idle script is installed by

Planned features for 2.3

Too late for anything more to get done here.

Ongoing tasks

The following are ongoing TO-DO items which we should attempt to work on without hoping for completion by any particular date.

  • Documentation: complete the distribution and installation manuals.
  • Documentation: complete the documentation for new-style classes.
  • Look over the Demos/ directory and update where required (Andrew Kuchling has done a lot of this)
  • New tests.
  • Fix doc bugs on SF.
  • Remove use of deprecated features in the core.
  • Document deprecated features appropriately.
  • Mark deprecated C APIs with Py_DEPRECATED.
  • Deprecate modules which are unmaintained, or perhaps make a new category for modules ‘Unmaintained’
  • In general, lots of cleanup so it is easier to move forward.

Open issues

There are some issues that may need more work and/or thought before the final release (and preferably before the first beta release): No issues remaining.

Features that did not make it into Python 2.3

  • The import lock could use some redesign. (SF 683658.)
  • Set API issues; is the sets module perfect?

    I expect it’s good enough to stop polishing it until we’ve had more widespread user experience.

  • A nicer API to open text files, replacing the ugly (in some people’s eyes) “U” mode flag. There’s a proposal out there to have a new built-in type textfile(filename, mode, encoding). (Shouldn’t it have a bufsize argument too?)


  • New widgets for Tkinter???

    Has anyone gotten the time for this? Are there any new widgets in Tk 8.4? Note that we’ve got better Tix support already (though not on Windows yet).

  • Fredrik Lundh’s basetime proposal:

    I believe this is dead now.

  • PEP 304 (Controlling Generation of Bytecode Files by Montanaro) seems to have lost steam.
  • For a class defined inside another class, the __name__ should be "outer.inner", and pickling should work. (SF 633930. I’m no longer certain this is easy or even right.)
  • reST is going to be used a lot in Zope3. Maybe it could become a standard library module? (Since reST’s author thinks it’s too unstable, I’m inclined not to do this.)
  • Decide on a clearer deprecation policy (especially for modules) and act on it. For a start, see this message from Neal Norwitz: There seems insufficient interest in moving this further in an organized fashion, and it’s not particularly important.
  • Provide alternatives for common uses of the types module;

    Skip Montanaro has posted a proto-PEP for this idea:

    There hasn’t been any progress on this, AFAICT.

  • Use pending deprecation for the types and string modules. This requires providing alternatives for the parts that aren’t covered yet (e.g. string.whitespace and types.TracebackType). It seems we can’t get consensus on this.
  • Deprecate the buffer object.

    It seems that this is never going to be resolved.

  • PEP 269 Pgen Module for Python, Riehl

    (Some necessary changes are in; the pgen module itself needs to mature more.)

  • Add support for the long-awaited Python catalog. Kapil Thangavelu has a Zope-based implementation that he demoed at OSCON 2002. Now all we need is a place to host it and a person to champion it. (Some changes to distutils to support this are in, at least.)
  • PEP 266 Optimizing Global Variable/Attribute Access, Montanaro

    PEP 267 Optimized Access to Module Namespaces, Hylton

    PEP 280 Optimizing access to globals, van Rossum

    These are basically three friendly competing proposals. Jeremy has made a little progress with a new compiler, but it’s going slow and the compiler is only the first step. Maybe we’ll be able to refactor the compiler in this release. I’m tempted to say we won’t hold our breath. In the meantime, Oren Tirosh has a much simpler idea that may give a serious boost to the performance of accessing globals and built-ins, by optimizing and inlining the dict access:

  • Lazily tracking tuples?

    Not much enthusiasm I believe.

  • PEP 286 Enhanced Argument Tuples, von Loewis

    I haven’t had the time to review this thoroughly. It seems a deep optimization hack (also makes better correctness guarantees though).

  • Make ‘as’ a keyword. It has been a pseudo-keyword long enough. Too much effort to bother.


Last modified: 2023-09-09 17:39:29 GMT