Previously deprecated [done]

PEP 4 lists all modules that have been deprecated in the stdlib. The specified motivations mirror those listed in PEP 4. All modules listed in the PEP at the time of the first alpha release of Python 3.0 will be removed.

The entire contents of lib-old will also be removed. These modules have already been removed from being imported but are kept in the distribution for Python for users that rely upon the code.

• cfmfile
  • Documented as deprecated since Python 2.4 without an explicit reason.
• cl
  • Documented as obsolete since Python 2.0 or earlier.
  • Interface to SGI hardware.
• md5
  • Supplanted by the hashlib module.
• mimetools
  • Documented as obsolete in a previous version.
  • Supplanted by the email package.
• MimeWriter
  • Supplanted by the email package.
• mimify
  • Supplanted by the email package.
• multifile
  • Supplanted by the email package.
• posixfile
  • Locking is better done by fcntl.lockf().
• rfc822
  • Supplanted by the email package.
• sha
  • Supplanted by the hashlib package.
• sv
  • Documented as obsolete since Python 2.0 or earlier.
  • Interface to obsolete SGI Indigo hardware.
• timing
  • Documented as obsolete since Python 2.0 or earlier.
  • time.clock() gives better time resolution.

Platform-specific with minimal use [done]

Python supports many platforms, some of which are not widely used or maintained. And on some of these platforms there are modules that have limited use to people on those platforms. Because of their limited usefulness it would be better to no longer burden the Python development team with their maintenance.

The modules mentioned below are documented. All undocumented modules for the specified platforms will also be removed.

Hardly used [done]

Some platform-independent modules are rarely used. There are a number of possible explanations for this, including, ease of reimplementation, very small audience or lack of adherence to more modern standards.

• audiodev
  • Undocumented.
  • Not edited in five years.
• imputil
  • Undocumented.
  • Never updated to support absolute imports.
• mutex
  • Easy to implement using a semaphore and a queue.
  • Cannot block on a lock attempt.
  • Not uniquely edited since its addition 15 years ago.
  • Only useful with the ‘sched’ module.
  • Not thread-safe.
• stringold
  • Function versions of the methods on string objects.
  • Obsolete since Python 1.6.
  • Any functionality not in the string object or module will be moved to the string module (mostly constants).
• sunaudio
  • Undocumented.
  • Not edited in over seven years.
  • The sunau module provides similar abilities.
• toaiff
  • Undocumented.
  • Requires sox library to be installed on the system.
• user
  • Easily handled by allowing the application specify its own module name, check for existence, and import if found.
• new
  • Just a rebinding of names from the ‘types’ module.
  • Can also call type built-in to get most types easily.
  • Docstring states the module is no longer useful as of revision 27241 (2002-06-15).
• pure
  • Written before Pure Atria was bought by Rational which was then bought by IBM (in other words, very old).
• test.testall
  • From the days before regrtest.

Obsolete

Becoming obsolete signifies that either another module in the stdlib or a widely distributed third-party library provides a better solution for what the module is meant for.

• Bastion/rexec [done]
  • Restricted execution / security.
  • Turned off in Python 2.3.
  • Modules deemed unsafe.
• bsddb185 [done]
  • Superseded by bsddb3
  • Not built by default.
  • Documentation specifies that the “module should never be used directly in new code”.
  • Available externally from PyPI.
• Canvas [done]
  • Marked as obsolete in a comment by Guido since 2000 (see http://bugs.python.org/issue210677).
  • Better to use the Tkinter.Canvas class.
• commands [done]
  • subprocess module replaces it (PEP 324).
  • Remove getstatus(), move rest to subprocess.
• compiler [done]
  • Having to maintain both the built-in compiler and the stdlib package is redundant [20].
  • The AST created by the compiler is available [19].
  • Mechanism to compile from an AST needs to be added.
• dircache [done]
  • Negligible use.
  • Easily replicated.
• dl [done]
  • ctypes provides better support for same functionality.
• fpformat [done]
  • All functionality is supported by string interpolation.
• htmllib [done]
  • Superseded by HTMLParser.
• ihooks [done]
  • Undocumented.
  • For use with rexec which has been turned off since Python 2.3.
• imageop [done]
  • Better support by third-party libraries (Python Imaging Library [13]).

  • Unit tests relied on rgbimg and imgfile.

    • rgbimg was removed in Python 2.6.
    • imgfile slated for removal in this PEP.

• linuxaudiodev [done]
  • Replaced by ossaudiodev.
• mhlib [done]
  • Should be removed as an individual module; use mailbox instead.
• popen2 [done]
  • subprocess module replaces it (PEP 324).
• sgmllib [done]
  • Does not fully parse SGML.
  • In the stdlib for support to htmllib which is slated for removal.
• sre [done]
  • Previously deprecated; import re instead.
• stat [TODO need to move all uses over to os.stat()]
  • os.stat() now returns a tuple with attributes.
  • Functions in the module should be made into methods for the object returned by os.stat.
• statvfs [done]
  • os.statvfs now returns a tuple with attributes.
• thread [done]
  • People should use ‘threading’ instead.
    • Rename ‘thread’ to _thread.
    • Deprecate dummy_thread and rename _dummy_thread.
    • Move thread.get_ident over to threading.
  • Guido has previously supported the deprecation [9].
• urllib [done]
  • Superseded by urllib2.
  • Functionality unique to urllib will be kept in the urllib package.
• UserDict [done: 3.0] [TODO handle 2.6]
  • Not as useful since types can be a superclass.
  • Useful bits moved to the ‘collections’ module.
• UserList/UserString [done]
  • Not useful since types can be a superclass.
  • Moved to the ‘collections’ module.

Maintenance Burden

Over the years, certain modules have become a heavy burden upon python-dev to maintain. In situations like this, it is better for the module to be given to the community to maintain to free python-dev to focus more on language support and other modules in the standard library that do not take up an undue amount of time and effort.

• bsddb3
  • Externally maintained at http://www.jcea.es/programacion/pybsddb.htm .
  • Consistent testing instability.
  • Berkeley DB follows a different release schedule than Python, leading to the bindings not necessarily being in sync with what is available.

PEP 8 violations [done]

PEP 8 specifies that modules “should have short, all-lowercase names” where “underscores can be used … if it improves readability”. The use of underscores is discouraged in package names. The following modules violate PEP 8 and are not somehow being renamed by being moved to a package.

Merging C and Python implementations of the same interface

Several interfaces have both a Python and C implementation. While it is great to have a C implementation for speed with a Python implementation as fallback, there is no need to expose the two implementations independently in the stdlib. For Python 3.0 all interfaces with two implementations will be merged into a single public interface.

The C module is to be given a leading underscore to delineate the fact that it is not the reference implementation (the Python implementation is). This means that any semantic difference between the C and Python versions must be dealt with before Python 3.0 or else the C implementation will be removed until it can be fixed.

One interface that is not listed below is xml.etree.ElementTree. This is an externally maintained module and thus is not under the direct control of the Python development team for renaming. See Open Issues for a discussion on this.

• pickle/cPickle [done]
  • Rename cPickle to _pickle.
  • Semantic completeness of C implementation not verified.
• profile/cProfile [TODO]
  • Rename cProfile to _profile.
  • Semantic completeness of C implementation not verified.
• StringIO/cStringIO [done]
  • Add the class to the ‘io’ module.

No public, documented interface [done]

There are several modules in the stdlib that have no defined public interface. These modules exist as support code for other modules that are exposed. Because they are not meant to be used directly they should be renamed to reflect this fact.

Poorly chosen names [done]

A few modules have names that were poorly chosen in hindsight. They should be renamed so as to prevent their bad name from perpetuating beyond the 2.x series.

Grouping of modules [done]

As the stdlib has grown, several areas within it have expanded to include multiple modules (e.g., support for database files). It thus makes sense to group related modules into packages.

Issues

Issues related to this PEP:

• Issue 2775: Master tracking issue
• Issue 2828: clean up undoc.rst

For modules to be removed

For module removals, it is easiest to remove the module first in Python 3.0 to see where dependencies exist. This makes finding code that (possibly) requires the suppression of the DeprecationWarning easier.

Renaming of modules

Support in the 2to3 refactoring tool for renames will be used to help people transition to new module names [11]. Import statements will be rewritten so that only the import statement and none of the rest of the code needs to be touched. This will be accomplished by using the as keyword in import statements to bind in the module namespace to the old name while importing based on the new name (when the keyword is not already used, otherwise the reassigned name should be left alone and only the module that is imported needs to be changed). The fix_imports fixer is an example of how to approach this.

Renaming of modules maintained outside of the stdlib

xml.etree.ElementTree not only does not meet PEP 8 naming standards but it also has an exposed C implementation. It is an externally maintained package, though PEP 360. A request will be made for the maintainer to change the name so that it matches PEP 8 and hides the C implementation.

Modules that were originally suggested for removal

• asynchat/asyncore
  • Josiah Carlson has said he will maintain the modules.
• audioop/sunau/aifc
  • Audio modules where the formats are still used.
• base64/quopri/uu
  • All still widely used.
  • ‘codecs’ module does not provide as nice of an API for basic usage.
• fileinput
  • Useful when having to work with stdin.
• linecache
  • Used internally in several places.
• nis
  • Testimonials from people that new installations of NIS are still occurring
• getopt
  • Simpler than optparse.
• repr
  • Useful as a basis for overriding.
  • Used internally.
• sched
  • Useful for simulations.
• symtable/_symtable
  • Docs were written.
• telnetlib
  • Really handy for quick-and-dirty remote access.
  • Some hardware supports using telnet for configuration and querying.
• Tkinter
  • Would prevent IDLE from existing.
  • No GUI toolkit would be available out of the box.

Introducing a new top-level package

It has been suggested that the entire stdlib be placed within its own package. This PEP will not address this issue as it has its own design issues (naming, does it deserve special consideration in import semantics, etc.). Everything within this PEP can easily be handled if a new top-level package is introduced.

Introducing new packages to contain theme-related modules

During the writing of this PEP it was noticed that certain themes appeared in the stdlib. In the past people have suggested introducing new packages to help collect modules that share a similar theme (e.g., audio). An Open Issue was created to suggest some new packages to introduce.

In the end, though, not enough support could be pulled together to warrant moving forward with the idea. Instead name simplification has been chosen as the guiding force for PEPs to create.