PEP: 4 Title: Deprecation of Standard Modules Version: $Revision$ Last-Modified: $Date$ Author: Brett Cannon , Martin von Löwis Status: Active Type: Process Content-Type: text/x-rst Created: 1-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, which SHOULD be a patch posted to bugs.python.org. 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 releases 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. 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. .. Local Variables: mode: indented-text indent-tabs-mode: nil sentence-end-double-space: t fill-column: 70 coding: utf-8 End: