python-peps/pep-3108.txt

PEP: 3108
Title: Standard Library Reorganization
Version: $Revision$
Last-Modified: $Date$
Author: Brett Cannon <brett@python.org>
Status: Draft
Type: Informational
Python-Version: 3.0
Content-Type: text/x-rst
Created: 01-Jan-2007
Post-History: 


Abstract
========

Just like the language itself, Python's standard library (stdlib) has
grown over the years to be very rich.  But over time some modules
have lost their need to be included with Python.  There has also been
an introduction of a naming convention for modules since Python's
inception that not all modules follow.

Python 3.0 has presented a chance to remove modules that do not have
long term usefulness.  This chance also allows for the renaming of
modules so that they follow the Python style guide [#pep-0008]_.  This
PEP lists modules that should not be included in Python 3.0 and what
modules need to be renamed.


Modules to Remove
=================

Guido pronounced that "silly old stuff" is to be deleted from the
stdlib for Py3K [#silly-old-stuff]_.  This is open-ended on purpose.
Each module to be removed needs to have a justification as to why it
should no longer be distributed with Python.  This can range from the
module being deprecated in Python 2.x to being for a platform that is
no longer widely used.

This section of the PEP lists the various modules to be removed. Each
subsection represents a different reason for modules to be
removed.  Each module must have a specific justification on top of
being listed in a specific subsection so as to make sure only modules
that truly deserve to be removed are in fact removed.

When a reason mentions how long it has been since a module has been
"uniquely edited", it is in reference to how long it has been since a
checkin was done specifically for the module and not for a change that
applied universally across the entire stdlib.  If an edit time is not
denoted as "unique" then it is the last time the file was edited,
period.


Previously deprecated
---------------------

Modules in this section have been deprecated at some point in the
Python 2.x release series but are currently still distributed with
Python.  Deprecation information is gathered either from PEP 4 or the
Global Module Index [#pep-0004]_, [#module-index]_.  Each module is
listed with the Python version of initial deprecation.

==============  ==========
Module          Deprecated
==============  ==========
buildtools      2.3
cfmfile         2.4
gopherlib       2.5
macfs           2.3
md5             2.5
mimetools       2.3
MimeWriter      2.3
mimefy          2.3
multifile       2.3
posixfile       1.5
rfc822          2.3
rgbimg          2.5
sha             2.5
==============  ==========


Platform-specific with minimal use
----------------------------------

Python supports many platforms, some of which are not widely held.
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.

* IRIX (which is no longer produced [#irix-retirement]_)

  + AL/al

    - Provides sound support on Indy and Indigo workstations.
    - Both workstations are no longer available.
    - Code has not been uniquely edited in three years.

  + cd

    - CD drive control for SGI systems.
    - SGI no longer sells machines with IRIX on them.
    - Code has not been uniquely edited in 14 years.

  + DEVICE/GL/gl/cgen/cgensuport

    - OpenGL access.
    - Has not been edited in at least eight years.
    - Third-party libraries provide better support (PyOpenGL [#pyopengl]_).

  + FL/fl/flp

    - Wrapper for the FORMS library [#irix-forms]_
    - FORMS has not been edited in 12 years.
    - Library is not widely used.
    - First eight hits on Google are for Python docs for fl.

  + fm

    - Wrapper to the IRIS Font Manager library.
    - Only available on SGI machines which no longer come with IRIX.

  + imgfile

    - Wrapper for SGI libimage library for imglib image files
      (``.rgb`` files).
    - Python Imaging Library provdes read-only support [#pil]_.
    - Not uniquely edited in 13 years.

  + jpeg

    - Wrapper for JPEG (de)compressor.
    - Code not uniquely edited in nine years.
    - Third-party libraries provide better support
      (Python Imaging Library [#pil]_).

  + sv

    - Wrapper for Indigo video card.
    - Harware is no longer manufactured.
    - Undocumented.
    - Code not uniquely edited in 13 years.

* Solaris

  + SUNAUDIODEV/sunaudiodev

    - Access to the sound card on Sun machines.
    - Code not uniquely edited in over eight years.

* Mac

  + applesingle

    - Undocumented.
    - AppleSingle is a binary file format for A/UX.
    - A/UX no longer distributed.


Minimal usage
-------------

Some modules that are platform-independent have minimal usage.  This
can be from how easy it is to implement the functionality from scratch
or because the audience for the code is small.

* audiodev

  + Undocumented.
  + Not edited in five years.
  + If removed sunaudio should go as well (also undocumented; not
    edited in over seven 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.

* repr

  + Controls output of the repr of objects.
  + String slicing and string interpolation can do similar work.
  + Used by pdb, but do not need to expose API.

* symtable/_symtable

  + Undocumented.

* 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.

* pure

  + Written before Pure Atria was bought by Rational which was then
    bought by IBM (in other words, very old).


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.

* base64/quopri/uu

  + Support exists in the codecs module.
  + If removed (along with binhex), also remove binascii
    (C implementation of base64, binhex, and uu modules).

* Bastion/rexec

  + Restricted execution / security.
  + Turned off in Python 2.3.
  + Modules deemed unsafe.

* dl

  + ctypes provides better support for same functionality.

* fpformat

  + All functionality is supported by string interpolation.

* getopt

  + optparse provides better functionality.

* ihooks

  + Documented except for saying that module might be obsolete.
  + For use with rexec which has been turned off since Python 2.3.

* imageop

  + Better support by third-party libraries
    (Python Imaging Library [#pil]_).

* linuxaudiodev

  + Replaced by ossaudiodev.

* 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

  + ``os.statvfs`` now returns a tuple with attributes.

* strop

  + Implements functions used by 'string' module that have now
    become methods on the str type.

* thread

  + People should use 'threading' instead.

    - Rename 'thread' to _thread.
    - Deprecate dummy_thread.

      * Rename to _mockthread.
      * Change of name better reflects modules purpose.

  + Guido has previously supported the deprecation
    [#thread-deprecation]_.

* timing

  + Use timeit or time.
  + Documentation says the module is obsolete [#timing-module]_.


Modules to Rename
=================

Along with the stdlib gaining some modules that are no longer
relevant, there is also the issue of naming.  Many modules existed in
the stdlib before PEP 8 came into existence [#pep-0008]_.  This has
led to some naming inconsistencies that should be addressed.

Any module that has been suggested for removal and does not meet the
required naming scheme is *not* listed below.


PEP 8 violations
----------------

PEP 8 specifies that modules "should have short, lowercase names,
without underscores" [#pep-0008]_.  There is no mention, though, if
this rule extends to modules contained within a package.  The
assumption is that underscores are acceptable in module names when
they are contained within a package but that any uppercase letters is
not.

==================  ==================================================
Current Name        Replacement Name
==================  ==================================================
_winreg             winreg (rename also because module has a public
                    interface)
autoGIL             autogil
BaseHTTPServer      basehttpserver
Carbon              carbon
CGIHTTPServer       cgihttpserver
ColorPicker         colorpicker
ConfigParser        configparser
Cookie              cookie
copy_reg            copyreg
DocXMLRPCServer     docxmlrpcserver
dummy_threading     mockthreading (rename because "mock" makes more
                    sense than "dummy" and rename already required)
EasyDialogs         easydialogs
FrameWork           framework
HTMLParser          htmlparser
MacOS               macos
MiniAEFrame         miniaeframe
Nav                 nav
PixMapWrapper       pixmapwrapper
py_compile          pycompile
Queue               queue
repr                reprlib (rename because module name shadows a 
                    built-in)
ScrolledText        scrolledtext
SimpleHTTPServer    simplehttpserver
SimpleXMLRPCServer  simplexmlrpcserver
SocketServer        socketserver
StringIO            stringio
Tix                 tix
Tkinter             tkinter
UserDict            userdict
UserList            userlist
UserString          userstring
W                   w
==================  ==================================================


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

  + Rename cPickle to _pickle.
  + Semantic completeness of C implementation *not* verified.

* profile/cProfile

  + Rename cProfile to _profile.
  + Semantic completeness of C implementation *not* verified.

* StringIO/cStringIO

  + Rename StringIO to stringio.
  + Rename cStringIO to _stringio.
  + Semantic completeness of C implementation *not* verified.


No public, documented interface
-------------------------------

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.

============  ===============================
Current Name  Replacement Name
============  ===============================
bdb           _bdb
markupbase    _markupbase
opcode        _opcode
dummythread   _mockthread (assuming the
              deprecation of 'thread' occurs)
============  ===============================


Transition Plan
===============

For modules to be removed
-------------------------

A PendingDeprecationWarning will be set in Python 2.6 for all modules
slated to be removed in Python 3.0.  This will allow people to know
which modules will not exist but without being overly noisy since
PendingDeprecationWarning is by default silenced.


For modules to be renamed
-------------------------

Modules will be renamed in Python 2.6.  The original names of the
modules will still work but will raise a PendingDeprecationWarning
upon import.  The refactoring tool for transitioning to Python 3.0
will refactor imports that use the new names.


Open Issues
===========

Consolidate dependent modules together into a single module or package?
-----------------------------------------------------------------------

The stdlib has several modules that have a level of dependency between
them (e.g., urllib and urllib2).  Usually one is a low-level module
that provides basic abilities with a corresponding higher-level API is
given in another module for simple use-cases.  In Python 3.0 we could
group these dependent modules together into a single module or package
to better reflect their relationship.

Keep in mind when looking at the groupings that deprecation or removal
is also a possibility if there is enough overlap or a module is
obsolete.

* Cookie/cookielib
* urllib/urllib2 (urlparse? httplib?)
* cgi/cgitb
* Tix/Tkinter
* getpass/pwd/spwd/grp
* mailbox/mhlib
* anydbm/whichdbm
* bsddb/dbhash
* pickle/pickletools
* HTMLParser/htmllib
* ftplib/netrc
* parser/symbol


Consolidate certain modules with similar themes together in a package?
----------------------------------------------------------------------

Packages are often used to group together modules that have a similar
theme but do not have any direct relationship or dependency upon each
other.  For Python 3.0 obvious groupings could be done since renaming
of various modules is already occurring.  Below is a list sectioned
off into what types of obvious groupings there seem to be.  No name
for the suggested package (if not already existent) is being proposed.

* collections

  + heapq
  + Queue
  + sets
  + UserDist
  + UserList
  + What to do with UserString?
    Have a package for Python implementations of built-in types
    instead of putting the User* modules into 'collections'?

* mac

  + Various Mac-specific modules.
  + Same can be done for other platform-specific code.

* Profiling

  + cProfile
  + profile
  + hotshot
  + pstats

* email

  + mailbox
  + mhlib

* Databases

  + anydbm
  + dbhash
  + dbm
  + bsddb
  + dumbdbm
  + gdbm
  + whichdb

* Audio

  + aifc
  + audioop
  + chunk
  + ossaudiodev
  + sunau
  + wave
  + winsound

* XML-RPC

  + DocXMLRPCServer
  + SimpleXMLRPCServer

* Web

  + urllib
  + urllib
  + urlparse
  + httplib
  + cgi
  + cgitb
  + BaseHTTPServer
  + BaseCGIServer
  + SimpleHTTPServer
  + htmllib
  + htmlentitydefs
  + HTMLParser
  + Cookie
  + cookielib
  + Could also just gather HTTP servers.


Modules reliant on obsolete/rarely used file formats?
-----------------------------------------------------

Several modules in the stdlib work on a specific file format.  It is
possible some of these formats are no longer used and thus the stdlib
modules for them can go.  Below is a list of some modules which rely
on a file format that may be obsolete.

aifc
    AIFF and AIFF-C audio files.  Appears to be only user of the cl
    module (which is undocumented).
audioop
    Raw (8|16|32)-bit wide audio files (as generated by the al and
    sunaudiodev modules).
binhex
    binhex4 encoding.
chunk
    AIFF, AIFF-C, and RMFF audio files.
sunau
    Sun AU audio files [#sun-au]_.


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 [#pep-0008]_.  It is an
externally maintained package, though [#pep-0360]_.  A request will be
made for the maintainer to change the name so that it matches PEP 8
and hides the C implementation.


Rejected Ideas
==============

Modules that were suggested for removal but were saved 
------------------------------------------------------

* asynchat/asyncore

  + Josiah Carlson has said he will help to maintain the modules.

* fileinput

  + Useful when having to work with stdin.

* nis

  + Testimonials from people that new installations of NIS are still
    occurring out in the world.

* telnetlib

  + Really handy for quick-and-dirty remote access.
  + Some hardware supports telnet for accessing it.


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.


References
==========

.. [#pep-0004] PEP 4: Deprecation of Standard Modules
    (http://www.python.org/dev/peps/pep-0004/)

.. [#pep-0008] PEP 8: Style Guide for Python Code
    (http://www.python.org/dev/peps/pep-0008/)

.. [#pep-0360] PEP 360: Externally Maintained Packages
    (http://www.python.org/dev/peps/pep-0360/)

.. [#module-index] Python Documentation: Global Module Index
    (http://docs.python.org/modindex.html)

.. [#timing-module] Python Library Reference: Obsolete
    (http://docs.python.org/lib/obsolete-modules.html)

.. [#silly-old-stuff] Python-Dev email: "Py3k release schedule worries"
    (http://mail.python.org/pipermail/python-3000/2006-December/005130.html)

.. [#thread-deprecation] Python-Dev email: Autoloading?
    (http://mail.python.org/pipermail/python-dev/2005-October/057244.html)

.. [#py-dev-summary-2004-11-01] Python-Dev Summary: 2004-11-01
    (http://www.python.org/dev/summary/2004-11-01_2004-11-15/#id10)

.. [#pyopengl] PyOpenGL
    (http://pyopengl.sourceforge.net/)

.. [#pil] Python Imaging Library (PIL)
    (http://www.pythonware.com/products/pil/)

.. [#twisted] Twisted
    (http://twistedmatrix.com/trac/)

.. [#irix-retirement] SGI Press Release:
    End of General Availability for MIPS IRIX Products -- December 2006
    (http://www.sgi.com/support/mips_irix.html)

.. [#irix-forms] FORMS Library by Mark Overmars
    (ftp://ftp.cs.ruu.nl/pub/SGI/FORMS)

.. [#sun-au] Wikipedia: Au file format
    (http://en.wikipedia.org/wiki/Au_file_format)


Copyright
=========

This document has been placed in the public domain.



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