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PEP: 4
Title: Deprecation of Standard Modules
Version: $Revision$
Last-Modified: $Date$
Author: Brett Cannon <brett@python.org>, Martin von Löwis <martin@v.loewis.de>
Status: Active
Type: Process
Content-Type: text/x-rst
Created: 01-Oct-2000
Post-History:
Introduction
============
When new modules were added to the standard Python library in the
past, it was not possible to foresee whether they would still be
useful in the future. Even though Python "Comes With Batteries
Included", batteries may discharge over time. Carrying old modules
around is a burden on the maintainer, especially when there is no
interest in the module anymore.
At the same time, removing a module from the distribution is
difficult, as it is not known in general whether anybody is still
using it. This PEP defines a procedure for removing modules from the
standard Python library. Usage of a module may be 'deprecated', which
means that it may be removed from a future Python release. The
rationale for deprecating a module is also collected in this PEP. If
the rationale turns out faulty, the module may become 'undeprecated'.
Procedure for declaring a module deprecated
===========================================
Since the status of module deprecation is recorded in this PEP,
proposals for deprecating modules MUST be made by providing a change
to the text of this PEP.
A proposal for deprecation of the module MUST include the date of the
proposed deprecation and a rationale for deprecating it. In addition,
the proposal MUST include a change to the documentation of the module;
deprecation is indicated by saying that the module is "obsolete" or
"deprecated". The proposal SHOULD include a patch for the module's
source code to indicate deprecation there as well, by raising a
DeprecationWarning. The proposal MUST include patches to remove any
use of the deprecated module from the standard library.
It is expected that deprecated modules are included in the Python
release that immediately follows the deprecation; later releases may
ship without the deprecated modules.
For modules existing in both Python 2.7 and Python 3.5
------------------------------------------------------
In order to facilitate writing code that works in both Python 2 & 3
simultaneously, any module that exists in both Python 3.5 and
Python 2.7 will not be removed from the standard library until
Python 2.7 is no longer supported as specified by :pep:`373`. Exempted
from this rule is any module in the idlelib package as well as any
exceptions granted by the Python development team.
Procedure for declaring a module undeprecated
=============================================
When a module becomes deprecated, a rationale is given for its
deprecation. In some cases, an alternative interface for the same
functionality is provided, so the old interface is deprecated. In
other cases, the need for having the functionality of the module may
not exist anymore.
If the rationale is faulty, again a change to this PEP's text MUST be
submitted. This change MUST include the date of undeprecation and a
rationale for undeprecation. Modules that are undeprecated under this
procedure MUST be listed in this PEP for at least one major release of
Python.
Obsolete modules
================
A number of modules are already listed as obsolete in the library
documentation. These are listed here for completeness.
cl, sv, timing
All these modules have been declared as obsolete in Python 2.0, some
even earlier.
The following obsolete modules were removed in Python 2.5:
addpack, cmp, cmpcache, codehack, dircmp, dump, find, fmt,
grep, lockfile, newdir, ni, packmail, Para, poly,
rand, reconvert, regex, regsub, statcache, tb, tzparse,
util, whatsound, whrandom, zmod
The following modules were removed in Python 2.6:
gopherlib, rgbimg, macfs
The following modules currently lack a DeprecationWarning:
rfc822, mimetools, multifile
Deprecated modules
==================
::
Module name: posixfile
Rationale: Locking is better done by fcntl.lockf().
Date: Before 1-Oct-2000.
Documentation: Already documented as obsolete. Deprecation
warning added in Python 2.6.
Module name: gopherlib
Rationale: The gopher protocol is not in active use anymore.
Date: 1-Oct-2000.
Documentation: Documented as deprecated since Python 2.5. Removed
in Python 2.6.
Module name: rgbimgmodule
Rationale: In a 2001-04-24 c.l.py post, Jason Petrone mentions
that he occasionally uses it; no other references to
its use can be found as of 2003-11-19.
Date: 1-Oct-2000
Documentation: Documented as deprecated since Python 2.5. Removed
in Python 2.6.
Module name: pre
Rationale: The underlying PCRE engine doesn't support Unicode, and
has been unmaintained since Python 1.5.2.
Date: 10-Apr-2002
Documentation: It was only mentioned as an implementation detail,
and never had a section of its own. This mention
has now been removed.
Module name: whrandom
Rationale: The module's default seed computation was
inherently insecure; the random module should be
used instead.
Date: 11-Apr-2002
Documentation: This module has been documented as obsolete since
Python 2.1, but listing in this PEP was neglected.
The deprecation warning will be added to the module
one year after Python 2.3 is released, and the
module will be removed one year after that.
Module name: rfc822
Rationale: Supplanted by Python 2.2's email package.
Date: 18-Mar-2002
Documentation: Documented as "deprecated since release 2.3" since
Python 2.2.2.
Module name: mimetools
Rationale: Supplanted by Python 2.2's email package.
Date: 18-Mar-2002
Documentation: Documented as "deprecated since release 2.3" since
Python 2.2.2.
Module name: MimeWriter
Rationale: Supplanted by Python 2.2's email package.
Date: 18-Mar-2002
Documentation: Documented as "deprecated since release 2.3" since
Python 2.2.2. Raises a DeprecationWarning as of
Python 2.6.
Module name: mimify
Rationale: Supplanted by Python 2.2's email package.
Date: 18-Mar-2002
Documentation: Documented as "deprecated since release 2.3" since
Python 2.2.2. Raises a DeprecationWarning as of
Python 2.6.
Module name: rotor
Rationale: Uses insecure algorithm.
Date: 24-Apr-2003
Documentation: The documentation has been removed from the library
reference in Python 2.4.
Module name: TERMIOS.py
Rationale: The constants in this file are now in the 'termios' module.
Date: 10-Aug-2004
Documentation: This module has been documented as obsolete since
Python 2.1, but listing in this PEP was neglected.
Removed from the library reference in Python 2.4.
Module name: statcache
Rationale: Using the cache can be fragile and error-prone;
applications should just use os.stat() directly.
Date: 10-Aug-2004
Documentation: This module has been documented as obsolete since
Python 2.2, but listing in this PEP was neglected.
Removed from the library reference in Python 2.5.
Module name: mpz
Rationale: Third-party packages provide similar features
and wrap more of GMP's API.
Date: 10-Aug-2004
Documentation: This module has been documented as obsolete since
Python 2.2, but listing in this PEP was neglected.
Removed from the library reference in Python 2.4.
Module name: xreadlines
Rationale: Using 'for line in file', introduced in 2.3, is preferable.
Date: 10-Aug-2004
Documentation: This module has been documented as obsolete since
Python 2.3, but listing in this PEP was neglected.
Removed from the library reference in Python 2.4.
Module name: multifile
Rationale: Supplanted by the email package.
Date: 21-Feb-2006
Documentation: Documented as deprecated as of Python 2.5.
Module name: sets
Rationale: The built-in set/frozenset types, introduced in
Python 2.4, supplant the module.
Date: 12-Jan-2007
Documentation: Documented as deprecated as of Python 2.6.
Module name: buildtools
Rationale: Unknown.
Date: 15-May-2007
Documentation: Documented as deprecated as of Python 2.3, but
listing in this PEP was neglected. Raised a
DeprecationWarning as of Python 2.6.
Module name: cfmfile
Rationale: Unknown.
Date: 15-May-2007
Documentation: Documented as deprecated as of Python 2.4, but
listing in this PEP was neglected. A
DeprecationWarning was added in Python 2.6.
Module name: macfs
Rationale: Unknown.
Date: 15-May-2007
Documentation: Documented as deprecated as of Python 2.3, but
listing in this PEP was neglected. Removed in
Python 2.6.
Module name: md5
Rationale: Replaced by the 'hashlib' module.
Date: 15-May-2007
Documentation: Documented as deprecated as of Python 2.5, but
listing in this PEP was neglected.
DeprecationWarning raised as of Python 2.6.
Module name: sha
Rationale: Replaced by the 'hashlib' module.
Date: 15-May-2007
Documentation: Documented as deprecated as of Python 2.5, but
listing in this PEP was neglected.
DeprecationWarning added in Python 2.6.
Module name: plat-freebsd2/IN and plat-freebsd3/IN
Rationale: Platforms are obsolete (last released in 2000)
Removed from 2.6
Date: 15-May-2007
Documentation: None
Module name: plat-freebsd4/IN and possibly plat-freebsd5/IN
Rationale: Platforms are obsolete/unsupported
Date: 15-May-2007
Remove from 2.7
Documentation: None
Module name: imp
Rationale: Replaced by the importlib module.
Date: 2013-02-10
Documentation: Deprecated as of Python 3.4.
Module name: formatter
Rationale: Lack of use in the community, no tests to keep
code working.
Date: 2013-08-12
Documentation: Deprecated as of Python 3.4.
Module name: macpath
Rationale: Obsolete macpath module dangerously broken
and should be removed.
Date: 2017-05-15
Documentation: Platform is obsolete/unsupported.
Module name: xml.etree.cElementTree
Rationale: Obsolete, use xml.etree.ElementTree
Date: 2019-04-06
Documentation: Documented as deprecated since 3.3
Deprecation of modules removed in Python 3.0
============================================
:pep:`3108` lists all modules that have been removed from Python 3.0.
They all are documented as deprecated in Python 2.6, and raise a
DeprecationWarning if the -3 flag is activated.
Undeprecated modules
====================
None.
Copyright
=========
This document has been placed in the public domain.
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