PEP: 594 Title: Removing dead batteries from the standard library Author: Christian Heimes Discussions-To: https://discuss.python.org/t/pep-594-removing-dead-batteries-from-the-standard-library/1704 Status: Draft Type: Standards Track Content-Type: text/x-rst Created: 20-May-2019 Post-History: 21-May-2019 Abstract ======== This PEP proposed a list of standard library modules to be removed from the standard library. The modules are mostly historic data formats (e.g. Commodore and SUN file formats), APIs and operating systems that have been superseded a long time ago (e.g. Mac OS 9), or modules that have security implications and better alternatives (e.g. password and login). The PEP follows in the foot steps of other PEPS like :pep:`3108`. The *Standard Library Reorganization* proposal removed a bunch of modules from Python 3.0. In 2007, the PEP referred to maintenance burden as: "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." The withdrawn :pep:`206` from 2000 expresses issues with the Python standard library unvarnished and fortright: "[...] the standard library modules aren't always the best choices for a job. Some library modules were quick hacks (e.g. ``calendar``, ``commands``), some were designed poorly and are now near-impossible to fix (``cgi``), and some have been rendered obsolete by other, more complete modules [...]." Rationale ========= Back in the early days of Python, the interpreter came with a large set of useful modules. This was often referred to as "batteries included" philosophy and was one of the cornerstones to Python's success story. Users didn't have to figure out how to download and install separate packages in order to write a simple web server or parse email. Times have changed. The introduction of the cheese shop (PyPI), setuptools, and later pip, it became simple and straightforward to download and install packages. Nowadays Python has a rich and vibrant ecosystem of third-party packages. It's pretty much standard to either install packages from PyPI or use one of the many Python or Linux distributions. On the other hand, Python's standard library is piling up cruft, unnecessary duplication of functionality, and dispensable features. This is undesirable for several reasons. * Any additional module increases the maintenance cost for the Python core development team. The team has limited resources, reduced maintenance cost frees development time for other improvements. * Modules in the standard library are generally favored and seen as the de facto solution for a problem. A majority of users only pick third-party modules to replace a stdlib module, when they have a compelling reason, e.g. ``lxml`` instead of ``xml``. The removal of an unmaintained stdlib module increases the chances of a community-contributed module to become widely used. * A lean and mean standard library benefits platforms with limited resources like devices with just a few hundred kilobyte of storage (e.g. BBC Micro:bit). Python on mobile platforms like BeeWare or WebAssembly (e.g. pyodide) also benefit from reduced download size. The modules in the PEP have been selected for deprecation because their removal is either least controversial or most beneficial. For example, least controversial are 30-year-old multimedia formats like the ``sunau`` audio format, which was used on SPARC and NeXT workstations in the late 1980s. The ``crypt`` module has fundamental flaws that are better solved outside the standard library. This PEP also designates some modules as not scheduled for removal. Some modules have been deprecated for several releases or seem unnecessary at first glance. However it is beneficial to keep the modules in the standard library, mostly for environments where installing a package from PyPI is not an option. This can be corporate environments or classrooms where external code is not permitted without legal approval. * The usage of FTP is declining, but some files are still provided over the FTP protocol or hosters offer FTP to upload content. Therefore, ``ftplib`` is going to stay. * The ``optparse`` and ``getopt`` modules are widely used. They are mature modules with very low maintenance overhead. * According to David Beazley [5]_ the ``wave`` module is easy to teach to kids and can make crazy sounds. Making a computer generate crazy sounds is powerful and highly motivating exercise for a nine-year-old aspiring developer. It's a fun battery to keep. Deprecation schedule ==================== 3.8 --- This PEP targets Python 3.8. Version 3.8.0 final is scheduled to be released a few months before Python 2.7 will reach its end of lifetime. We expect that Python 3.8 will be targeted by users that migrate to Python 3 in 2019 and 2020. To reduce churn and to allow a smooth transition from Python 2, Python 3.8 will neither raise ``DeprecationWarning`` nor remove any modules that have been scheduled for removal. Instead deprecated modules will just be *documented* as deprecated. Optionally modules may emit a ``PendingDeprecationWarning``. All deprecated modules will also undergo a feature freeze. No additional features should be added *unless* python-dev agrees that the deprecation of the module is reverted and the code will not be removed. Bug should still be fixed. 3.9 --- Starting with Python 3.9, deprecated modules will start issuing ``DeprecationWarning``. The `parser`_ module is removed and potentially replaced with a new module. All other deprecated modules are fully supported and will receive security updates until Python 3.9 reaches its end-of-life. Python 3.9.0 will be released about 18 months after 3.8.0 (April 2021?) and most likely be supported for five years after the release. The estimated EOL of Python 3.9 is in 2026. 3.10 ---- In 3.10 all deprecated modules will be removed from the CPython repository together with tests, documentation, and autoconf rules. PEP acceptance process ====================== 3.8.0b1 is scheduled to be release shortly after the PEP is officially submitted. Since it's improbable that the PEP will pass all stages of the PEP process in time, I propose a two-step acceptance process that is analogous to Python's two-release deprecation process. The first *provisionally-accepted* phase targets Python 3.8.0b1. In the first phase no code is changed or removed. Modules are only documented as deprecated. The only exception is the `parser`_ module. It has been documented as deprecated since Python 2.5 and is scheduled for removal for 3.9 to make place for a more advanced parser. The final decision, which modules will be removed and how the removed code is preserved, can be delayed for another year. Deprecated modules ================== The modules are grouped as data encoding, multimedia, network, OS interface, and misc modules. The majority of modules are for old data formats or old APIs. Some others are rarely useful and have better replacements on PyPI, e.g. Pillow for image processing or NumPy-based projects to deal with audio processing. .. csv-table:: Table 1: Proposed modules deprecations :header: "Module", "Deprecated in", "To be removed", "Added in", "Has maintainer?", "Replacement" :widths: 2, 1, 1, 1, 1, 2 aifc,3.8 (3.0\*),3.10,1993,**yes (inactive)**,\- asynchat,**3.6** (3.0\*),3.10,1999,**yes**,asyncio_ asyncore,**3.6** (3.0\*),3.10,1999,**yes**,asyncio_ audioop,3.8 (3.0\*),3.10,1992,**yes**,\- binhex,3.8,3.10,1995,no,\- cgi,3.8 (2.0\*\*),3.10,1995,no,\- cgitb,3.8 (2.0\*\*),3.10,1995,no,\- chunk,3.8,3.10,1999,no,\- crypt,3.8,3.10,1994,**yes (inactive)**,"legacycrypt_, bcrypt_, argon2cffi_, hashlib_, passlib_" formatter,**3.4**,3.10,1995,no,\- fpectl,**3.7**,**3.7**,1997,n/a,\- imghdr,3.8,3.10,1992,no,"filetype_, puremagic_, python-magic_" imp,**3.4**,3.10,1990/1995,no,importlib_ macpath,**3.7**,**3.8**,1990,n/a,\- msilib,3.8,3.10,2006,no,\- nntplib,3.8,3.10,1992,no,\- nis,3.8 (3.0\*),3.10,1992,no,\- ossaudiodev,3.8,3.10,2002,no,\- parser,**2.5**,**3.9**,1993,**yes**,"ast_, astroid_, lib2to3.pgen2" pipes,3.8,3.10,1992,no,"subprocess_" smtpd,"**3.4.7**, **3.5.4**",3.10,2001,**yes**,"aiosmtpd_" sndhdr,3.8,3.10,1994,no,"filetype_, puremagic_, python-magic_" spwd,3.8,3.10,2005,no,"python-pam_, simplepam_" sunau,3.8 (3.0\*),3.10,1993,no,\- telnetlib,3.8 (3.0\*),3.10,1997,no,"telnetlib3_, Exscript_" uu,3.8,3.10,1994,no,\- xdrlib,3.8,3.10,1992/1996,no,\- .. _aiosmtpd: https://pypi.org/project/aiosmtpd/ .. _argon2cffi: https://pypi.org/project/argon2-cffi/ .. _ast: https://docs.python.org/3/library/ast.html .. _astroid: https://pypi.org/project/astroid/ .. _asyncio: https://docs.python.org/3/library/hashlib.html .. _bcrypt: https://pypi.org/project/bcrypt/ .. _Exscript: https://pypi.org/project/Exscript/ .. _filetype: https://pypi.org/project/filetype/ .. _hashlib: https://docs.python.org/3/library/hashlib.html .. _importlib: https://docs.python.org/3/library/importlib.html .. _legacycrypt: https://pypi.org/project/legacycrypt/ .. _passlib: https://pypi.org/project/passlib/ .. _puremagic: https://pypi.org/project/puremagic/ .. _python-magic: https://pypi.org/project/python-magic/ .. _python-pam: https://pypi.org/project/python-pam/ .. _simplepam: https://pypi.org/project/simplepam/ .. _subprocess: https://docs.python.org/3/library/subprocess.html .. _telnetlib3: https://pypi.org/project/telnetlib3/ Some module deprecations proposed by :pep:`3108` for 3.0 and :pep:`206` for 2.0. The *added in* column illustrates, when a module was originally designed and added to the standard library. The *has maintainer* column refers to the `expert index `_, a list of domain experts and maintainers in the DevGuide. Data encoding modules --------------------- binhex ~~~~~~ The `binhex `_ module encodes and decodes Apple Macintosh binhex4 data. It was originally developed for TRS-80. In the 1980s and early 1990s it was used on classic Mac OS 9 to encode binary email attachments. Module type pure Python Deprecated in 3.8 To be removed in 3.10 Has a designated expert no Substitute **none** uu and the uu encoding ~~~~~~~~~~~~~~~~~~~~~~ The `uu `_ module provides uuencode format, an old binary encoding format for email from 1980. The uu format has been replaced by MIME. The uu codec is provided by the ``binascii`` module. There's also ``encodings/uu_codec.py`` which is a codec for the same encoding; it should also be deprecated. Module type pure Python Deprecated in 3.8 To be removed in 3.10 Has a designated expert no Substitute **none** xdrlib ~~~~~~ The `xdrlib `_ module supports the Sun External Data Representation Standard. XDR is an old binary serialization format from 1987. These days it's rarely used outside specialized domains like NFS. Module type pure Python Deprecated in 3.8 To be removed in 3.10 Has a designated expert no Substitute **none** Multimedia modules ------------------ aifc ~~~~ The `aifc `_ module provides support for reading and writing AIFF and AIFF-C files. The Audio Interchange File Format is an old audio format from 1988 based on Amiga IFF. It was most commonly used on the Apple Macintosh. These days only few specialized application use AIFF. A user disclosed [8]_ that the post production film industry makes heavy use of the AIFC file format. The usage of the ``aifc`` module in closed source and internal software was unknown prior to the first posting of this PEP. This may be a compelling argument to keep the ``aifc`` module in the standard library. The file format is stable and the module does not require much maintenance. The strategic benefits for Python may outmatch the burden. Module type pure Python (depends on some functions from `audioop`_ C extension) Deprecated in 3.8 To be removed in 3.10 Has a designated expert yes, but expert is currently inactive. Substitute **none** audioop ~~~~~~~ The `audioop `_ module contains helper functions to manipulate raw audio data and adaptive differential pulse-code modulated audio data. The module is implemented in C without any additional dependencies. The `aifc`_, `sunau`_, and `wave`_ modules depend on `audioop`_ for some operations. The byteswap operation in the ``wave`` module can be substituted with little extra work. In case ``aifc`` is not deprecated as well, a reduced version of the ``audioop`` module is converted into a private implementation detail, e.g. ``_audioop`` with ``byteswap``, ``alaw2lin``, ``ulaw2lin``, ``lin2alaw``, ``lin2ulaw``, and ``lin2adpcm``. Module type C extension Deprecated in 3.8 To be removed in 3.10 Has a designated expert yes Substitute **none** chunk ~~~~~ The `chunk `_ module provides support for reading and writing Electronic Arts' Interchange File Format. IFF is an old audio file format originally introduced for Commodore and Amiga. The format is no longer relevant. Module type pure Python Deprecated in 3.8 To be removed in 3.10 Has a designated expert no Substitute **none** imghdr ~~~~~~ The `imghdr `_ module is a simple tool to guess the image file format from the first 32 bytes of a file or buffer. It supports only a limited number of formats and neither returns resolution nor color depth. Module type pure Python Deprecated in 3.8 To be removed in 3.10 Has a designated expert no Substitute `puremagic `_, `filetype `_, `python-magic `_ ossaudiodev ~~~~~~~~~~~ The `ossaudiodev `_ module provides support for Open Sound System, an interface to sound playback and capture devices. OSS was initially free software, but later support for newer sound devices and improvements were proprietary. Linux community abandoned OSS in favor of ALSA [1]_. Some operation systems like OpenBSD and NetBSD provide an incomplete [2]_ emulation of OSS. To best of my knowledge, FreeBSD is the only widespread operating system that uses Open Sound System as of today. The ``ossaudiodev`` hasn't seen any improvements or new features since 2003. All commits since 2003 are project-wide code cleanups and a couple of bug fixes. It would be beneficial for both FreeBSD community and core development, if the module would be maintained and distributed by people that care for it and use it. The standard library used to have more audio-related modules. The other audio device interface (``audiodev``, ``linuxaudiodev``, ``sunaudiodev``) were removed in 2007 as part of the :pep:`3108` stdlib re-organization. Module type C extension Deprecated in 3.8 To be removed in 3.10 Has a designated expert no Substitute **none** sndhdr ~~~~~~ The `sndhdr `_ module is similar to the `imghdr`_ module but for audio formats. It guesses file format, channels, frame rate, and sample widths from the first 512 bytes of a file or buffer. The module only supports AU, AIFF, HCOM, VOC, WAV, and other ancient formats. Module type pure Python (depends on `audioop`_ C extension for some operations) Deprecated in 3.8 To be removed in 3.10 Has a designated expert no Substitute `puremagic `_, `filetype `_, `python-magic `_ sunau ~~~~~ The `sunau `_ module provides support for Sun AU sound format. It's yet another old, obsolete file format. Module type pure Python (depends on `audioop`_ C extension for some operations) Deprecated in 3.8 To be removed in 3.10 Has a designated expert no Substitute **none** Networking modules ------------------ asynchat ~~~~~~~~ The `asynchat `_ module is built on top of `asyncore`_ and has been deprecated since Python 3.6. Module type pure Python Deprecated in 3.6 Removed in 3.10 Has a designated expert yes Substitute asyncio asyncore ~~~~~~~~ The `asyncore `_ module was the first module for asynchronous socket service clients and servers. It has been replaced by asyncio and is deprecated since Python 3.6. The ``asyncore`` module is also used in stdlib tests. The tests for ``ftplib``, ``logging``, ``smptd``, ``smtplib``, and ``ssl`` are partly based on ``asyncore``. These tests must be updated to use asyncio or threading. Module type pure Python Deprecated in 3.6 Removed in 3.10 Has a designated expert yes Substitute asyncio cgi ~~~ The `cgi `_ module is a support module for Common Gateway Interface (CGI) scripts. CGI is deemed as inefficient because every incoming request is handled in a new process. :pep:`206` considers the module as: "[...] designed poorly and are now near-impossible to fix (``cgi``) [...]" Several people proposed to either keep the ``cgi`` module for features like ``cgi.parse_qs`` or move ``cgi.escape`` to a different module. The functions ``cgi.parse_qs`` and ``cgi.parse_qsl`` have been deprecated for a while and are actually aliases for ``urllib.parse.parse_qs`` and ``urllib.parse.parse_qsl``. The function ``cgi.quote`` has been deprecated in favor of ``html.quote`` with secure default values. Module type pure Python Deprecated in 3.8 (originally proposed for 2.0 by :pep:`206`) To be removed in 3.10 Has a designated expert no Substitute **none** cgitb ~~~~~ The `cgitb `_ module is a helper for the ``cgi`` module for configurable tracebacks. The ``cgitb`` module is not used by any major Python web framework (Django, Pyramid, Plone, Flask, CherryPy, or Bottle). Only Paste uses it in an optional debugging middleware. Module type pure Python Deprecated in 3.8 (originally proposed for 2.0 by :pep:`206`) To be removed in 3.10 Has a designated expert no Substitute **none** smtpd ~~~~~ The `smtpd `_ module provides a simple implementation of a SMTP mail server. The module documentation marks the module as deprecated and recommends ``aiosmtpd`` instead. The deprecation message was added in releases 3.4.7, 3.5.4, and 3.6.1. Module type pure Python Deprecated in **3.4.7**, **3.5.4**, **3.6.1** To be removed in 3.10 Has a designated expert yes Substitute aiosmtpd nntplib ~~~~~~~ The `nntplib `_ module implements the client side of the Network News Transfer Protocol (nntp). News groups used to be a dominant platform for online discussions. Over the last two decades, news has been slowly but steadily replaced with mailing lists and web-based discussion platforms. Twisted is also `planning `_ to deprecate NNTP support and `pynntp `_ hasn't seen any activity since 2014. This is a good indicator that the public interest in NNTP support is declining. The ``nntplib`` tests have been the cause of additional work in the recent past. Python only contains client side of NNTP. The tests connect to external news server. The servers are sometimes unavailable, too slow, or do not work correctly over IPv6. The situation causes flaky test runs on buildbots. Module type pure Python Deprecated in 3.8 To be removed in 3.10 Has a designated expert no Substitute **none** telnetlib ~~~~~~~~~ The `telnetlib `_ module provides a Telnet class that implements the Telnet protocol. Module type pure Python Deprecated in 3.8 To be removed in 3.10 Substitute telnetlib3_, Exscript_ Operating system interface -------------------------- crypt ~~~~~ The `crypt `_ module implements password hashing based on the ``crypt(3)`` function from ``libcrypt`` or ``libxcrypt`` on Unix-like platforms. The algorithms are mostly old, of poor quality and insecure. Users are discouraged to use them. * The module is not available on Windows. Cross-platform applications need an alternative implementation anyway. * Only DES encryption is guaranteed to be available. DES has an extremely limited key space of 2**56. * MD5, salted SHA256, salted SHA512, and Blowfish are optional extensions. SSHA256 and SSHA512 are glibc extensions. Blowfish (bcrypt) is the only algorithm that is still secure. However it's in glibc and therefore not commonly available on Linux. * Depending on the platform, the ``crypt`` module is not thread safe. Only implementations with ``crypt_r(3)`` are thread safe. * The module was never useful to interact with system user and password databases. On BSD, macOS, and Linux, all user authentication and password modification operations must go through PAM (pluggable authentication module), see `spwd`_ deprecation. Module type C extension + Python module Deprecated in 3.8 To be removed in 3.10 Has a designated expert yes, but expert is currently inactive. Substitute `legacycrypt `_ (ctypes wrapper), `bcrypt `_, `passlib `_, `argon2cffi `_, hashlib module (PBKDF2, scrypt) macpath ~~~~~~~ The `macpath `_ module provides Mac OS 9 implementation of ``os.path`` routines. Mac OS 9 is no longer supported. Module type pure Python Deprecated in 3.7 Removed in 3.8 Has a designated expert n/a Substitute **none** nis ~~~ The `nis `_ module provides NIS/YP support. Network Information Service / Yellow Pages is an old and deprecated directory service protocol developed by Sun Microsystems. It's designed successor NIS+ from 1992 never took off. For a long time, libc's Name Service Switch, LDAP, and Kerberos/GSSAPI are considered a more powerful and more secure replacement of NIS. Module type C extension Deprecated in 3.8 To be removed in 3.10 Has a designated expert no Substitute **none** spwd ~~~~ The `spwd `_ module provides direct access to Unix shadow password database using non-standard APIs. In general it's a bad idea to use spwd. It circumvents system security policies, does not use the PAM stack, and is only compatible with local user accounts, because it ignores NSS. The use of the ``spwd`` module for access control must be considered a *security bug*, as it bypasses PAM's access control. Further more the ``spwd`` module uses the `shadow(3) `_ APIs. Functions like ``getspnam(3)`` access the ``/etc/shadow`` file directly. This is dangerous and even forbidden for confined services on systems with a security engine like SELinux or AppArmor. Module type C extension Deprecated in 3.8 To be removed in 3.10 Has a designated expert no Substitute `python-pam `_, `simpleplam `_ Misc modules ------------ formatter ~~~~~~~~~ The `formatter `_ module is an old text formatting module which has been deprecated since Python 3.4. Module type pure Python Deprecated in 3.4 To be removed in 3.10 Has a designated expert no Substitute *n/a* imp ~~~ The `imp `_ module is the predecessor of the `importlib `_ module. Most functions have been deprecated since Python 3.3 and the module since Python 3.4. Module type C extension Deprecated in 3.4 To be removed in 3.10 Has a designated expert yes, experts have deprecated the module Substitute importlib msilib ~~~~~~ The `msilib `_ package is a Windows-only package. It supports the creation of Microsoft Installers (MSI). The package also exposes additional APIs to create cabinet files (CAB). The module is used to facilitate distutils to create MSI installers with the ``bdist_msi`` command. In the past it was used to create CPython's official Windows installer, too. Microsoft is slowly moving away from MSI in favor of Windows 10 Apps (AppX) as new deployment model [3]_. Module type C extension + Python code Deprecated in 3.8 To be removed in 3.10 Has a designated expert no Substitute **none** parser ~~~~~~ The `parser `_ module provides an interface to Python’s internal parser and bytecode compiler. The stdlib has superior ways to interact with the parse tree. From Python 2.5 onward, it's much more convenient to cut in at the Abstract Syntax Tree (AST) generation and compilation stage. The ``parser`` module causes additional work. It's C code that must be kept in sync with any change to Python's grammar and internal parser. Pablo wants to remove the parser module and promote lib2to3's pgen2 instead [6]_. Most importantly the presence of the ``parser`` module makes it harder to switch to something more powerful than a LL(1) parser [7]_. Since the ``parser`` module is documented as deprecated since Python 2.5 and a new parsing technology is planned for 3.9, the ``parser`` module is scheduled for removal in 3.9. Module type C extension Deprecated in 3.8, documented as deprecated since **2.5** To be removed in **3.9** Has a designated expert yes, experts have deprecated the module. Substitute ast, lib2to3.pgen2 pipes ~~~~~ The `pipes `_ module provides helpers to pipe the input of one command into the output of another command. The module is built on top of ``os.popen``. Users are encouraged to use the subprocess module instead. Module type pure Python Deprecated in 3.8 To be removed in 3.10 Has a designated expert no Substitute subprocess module Removed modules =============== fpectl ------ The `fpectl `_ module was never built by default, its usage was discouraged and considered dangerous. It also required a configure flag that caused an ABI incompatibility. The module was removed in 3.7 by Nathaniel J. Smith in `bpo-29137 `_. Module type C extension + CAPI Deprecated in 3.7 Removed in 3.7 Has a designated expert n/a Substitute **none** Modules to keep =============== Some modules were originally proposed for deprecation. .. csv-table:: Table 2: Withdrawn deprecations :header: "Module", "Deprecated in", "Replacement" :widths: 1, 1, 2 colorsys,\-,"colormath, colour, colorspacious, Pillow" fileinput,\-,argparse getopt,\-,"argparse, optparse" lib2to3,\-, optparse,**3.2**,argparse wave,\-, colorsys -------- The `colorsys `_ module defines color conversion functions between RGB, YIQ, HSL, and HSV coordinate systems. Walter Dörwald, Petr Viktorin, and others requested to keep ``colorsys``. The module is useful to convert CSS colors between coordinate systems. The implementation is simple, mature, and does not impose maintenance overhead on core development. The PyPI packages ``colormath``, ``colour``, and ``colorspacious`` provide more and advanced features. The Pillow library is better suited to transform images between color systems. Module type pure Python Has a designated expert no Substitute `colormath `_, `colour `_ `colorspacious `_, `Pillow `_ fileinput --------- The `fileinput `_ module implements helpers to iterate over a list of files from ``sys.argv``. The module predates the ``optparser`` and ``argparser`` modules. The same functionality can be implemented with the ``argparser`` module. Several core developers expressed their interest to keep the module in the standard library, as it is handy for quick scripts. Module type pure Python Has a designated expert no lib2to3 ------- The `lib2to3 `_ package provides the ``2to3`` command to transpile Python 2 code to Python 3 code. The package is useful for other tasks besides porting code from Python 2 to 3. For example, `Black`_ uses it for code reformatting. Module type pure Python Has a designated expert no getopt ------ The `getopt `_ module mimics C's ``getopt()`` option parser. Although users are encouraged to use ``argparse`` instead, the ``getopt`` module is still widely used. The module is small, simple, and handy for C developers to write simple Python scripts. Module type pure Python Has a designated expert no Substitute argparse optparse -------- The `optparse `_ module is the predecessor of the ``argparse`` module. Although it has been deprecated for many years, it's still too widely used to remove it. Module type pure Python Deprecated in 3.2 Has a designated expert yes Substitute argparse wave ---- The `wave `_ module provides support for the WAV sound format. The module is not deprecated, because The WAV format is still relevant these days. The ``wave`` module is also used in education, e.g. to show kids how to make noise with a computer. The module uses one simple function from the `audioop`_ module to perform byte swapping between little and big endian formats. Before 24 bit WAV support was added, byte swap used to be implemented with the ``array`` module. To remove ``wave``'s dependency on ``audioop``, the byte swap function could be either be moved to another module (e.g. ``operator``) or the ``array`` module could gain support for 24-bit (3-byte) arrays. Module type pure Python (depends on *byteswap* from `audioop`_ C extension) Has a designated expert no Future maintenance of removed modules ===================================== The main goal of the PEP is to reduce the burden and workload on the Python core developer team. Therefore, removed modules will not be maintained by the core team as separate PyPI packages. However the removed code, tests and documentation may be moved into a new Git repository, so community members have a place from which they can pick up and fork code. A first draft of a `legacylib `_ repository is available on my private GitHub account. The modules could be made available on PyPI. The Python core team will not publish or maintain the packages. It is my hope that members of the Python community will adopt, maintain, and perhaps improve the deprecated modules. It's my hope that some of the deprecated modules will be picked up and adopted by users that actually care about them. For example, ``colorsys`` and ``imghdr`` are useful modules, but have limited feature set. A fork of ``imghdr`` can add new features and support for more image formats, without being constrained by Python's release cycle. Most of the modules are in pure Python and can be easily packaged. Some depend on a simple C module, e.g. `audioop`_ and `crypt`_. Since `audioop`_ does not depend on any external libraries, it can be shipped as binary wheels with some effort. Other C modules can be replaced with ``ctypes`` or ``cffi``. For example, I created `legacycrypt`_, which provides a full implementation of ``crypt``. It is implemented on top of a ctypes wrapper around ``libxcrypt`` and ``libcrypt`` instead of a C extension like the original ``_crypt`` module. Discussions =========== * Elana Hashman and Nick Coghlan suggested to keep the ``getopt`` module. * Berker Peksag proposed to deprecate and removed ``msilib``. * Brett Cannon recommended to delay active deprecation warnings and removal of modules like ``imp`` until Python 3.10. Version 3.8 will be released shortly before Python 2 reaches end-of-life. A delay reduced churn for users that migrate from Python 2 to 3.8. * Brett also came up with the idea to keep ``lib2to3``. The package is useful for other purposes, e.g. `Black `_ uses it to reformat Python code. * At one point, distutils was mentioned in the same sentence as this PEP. To avoid lengthy discussion and delay of the PEP, I decided against dealing with distutils. Deprecation of the distutils package will be handled by another PEP. * Multiple people (Gregory P. Smith, David Beazley, Nick Coghlan, ...) convinced me to keep the `wave`_ module. [4]_ * Gregory P. Smith proposed to deprecate `nntplib`_. [4]_ * Andrew Svetlov mentioned the ``socketserver`` module is questionable. However it's used to implement ``http.server`` and ``xmlrpc.server``. The stdlib doesn't have a replacement for the servers, yet. Update history ============== Update 1 -------- * Deprecate `parser`_ module * Keep `fileinput`_ module * Elaborate why ``crypt`` and ``spwd`` are dangerous and bad * Improve sections for `cgitb`_, `colorsys`_, `nntplib`_, and `smtpd`_ modules * The `colorsys`_, ``crypt``, `imghdr`_, `sndhdr`_, and ``spwd`` sections now list suitable substitutions * Mention that ``socketserver`` is going to stay for ``http.server`` and ``xmlrpc.server`` * The future maintenance section now states that the deprecated modules may be adopted by Python community members Update 2 -------- * Keep ``colorsys`` module * Add experts * Redirect discussions to discuss.python.org * Deprecate `telnetlib`_ * Deprecate compat32 policy of email package * Add creation year to overview table * Mention :pep:`206` and :pep:`3108` * Update sections for ``aifc``, ``audioop``, ``cgi``, and ``wave``. Update 3 -------- * Keep the legacy email API modules. Internal deprecations will be handled separately. References ========== .. [1] https://en.wikipedia.org/wiki/Open_Sound_System#Free,_proprietary,_free .. [2] https://man.openbsd.org/ossaudio .. [3] https://blogs.msmvps.com/installsite/blog/2015/05/03/the-future-of-windows-installer-msi-in-the-light-of-windows-10-and-the-universal-windows-platform/ .. [4] https://twitter.com/ChristianHeimes/status/1130257799475335169 .. [5] https://twitter.com/dabeaz/status/1130278844479545351 .. [6] https://mail.python.org/pipermail/python-dev/2019-May/157464.html .. [7] https://discuss.python.org/t/switch-pythons-parsing-tech-to-something-more-powerful-than-ll-1/379 .. [8] https://mail.python.org/pipermail/python-dev/2019-May/157634.html 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: