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PEP: 594
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Title: Removing dead batteries from the standard library
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Author: Christian Heimes <christian@python.org>
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Discussions-To: https://discuss.python.org/t/pep-594-removing-dead-batteries-from-the-standard-library/1704
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Status: Draft
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Type: Standards Track
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Content-Type: text/x-rst
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Created: 20-May-2019
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Post-History: 21-May-2019
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Abstract
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========
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This PEP proposed a list of standard library modules to be removed from the
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standard library. The modules are mostly historic data formats and APIs that
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have been superseded a long time ago, e.g. Mac OS 9 and Commodore.
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Rationale
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=========
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Back in the early days of Python, the interpreter came with a large set of
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useful modules. This was often refrained to as "batteries included"
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philosophy and was one of the corner stones to Python's success story.
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Users didn't have to figure out how to download and install separate
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packages in order to write a simple web server or parse email.
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Times have changed. The introduction of the cheese shop (PyPI), setuptools,
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and later pip, it became simple and straight forward to download and install
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packages. Nowadays Python has a rich and vibrant ecosystem of third party
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packages. It's pretty much standard to either install packages from PyPI or
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use one of the many Python or Linux distributions.
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On the other hand, Python's standard library is piling up cruft, unnecessary
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duplication of functionality, and dispensable features. This is undesirable
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for several reasons.
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* Any additional module increases the maintenance cost for the Python core
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development team. The team has limited resources, reduced maintenance cost
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frees development time for other improvements.
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* Modules in the standard library are generally favored and seen as the
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de-facto solution for a problem. A majority of users only pick 3rd party
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modules to replace a stdlib module, when they have a compelling reason, e.g.
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lxml instead of `xml`. The removal of an unmaintained stdlib module
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increases the chances of a community contributed module to become widely
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used.
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* A lean and mean standard library benefits platforms with limited resources
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like devices with just a few hundred kilobyte of storage (e.g. BBC
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Micro:bit). Python on mobile platforms like BeeWare or WebAssembly
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(e.g. pyodide) also benefit from reduced download size.
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The modules in the PEP have been selected for deprecation because their
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removal is either least controversial or most beneficial. For example
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least controversial are 30 years old multimedia formats like ``sunau``
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audio format, which was used on SPARC and NeXT workstations in the late
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1980ties. The ``crypt`` module has fundamental flaws that are better solved
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outside the standard library.
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This PEP also designates some modules as not scheduled for removal. Some
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modules have been deprecated for several releases or seem unnecessary at
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first glance. However it is beneficial to keep the modules in the standard
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library, mostly for environments where installing a package from PyPI is not
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an option. This can be cooperate environments or class rooms where external
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code is not permitted without legal approval.
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* The usage of FTP is declining, but some files are still provided over
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the FTP protocol or hosters offer FTP to upload content. Therefore
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``ftplib`` is going to stay.
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* The ``optparse`` and ``getopt`` module are widely used. They are mature
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modules with very low maintenance overhead.
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* According to David Beazley [5]_ the ``wave`` module is easy to teach to
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kids and can make crazy sounds. Making a computer generate crazy sounds is
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powerful and highly motivating exercise for a 9yo aspiring developer. It's
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a fun battery to keep.
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Deprecation schedule
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====================
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3.8
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---
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This PEP targets Python 3.8. Version 3.8.0 final is scheduled to be released
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a few months before Python 2.7 will reach its end of lifetime. We expect that
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Python 3.8 will be targeted by users that migrate to Python 3 in 2019 and
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2020. To reduce churn and to allow a smooth transition from Python 2,
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Python 3.8 will neither raise `DeprecationWarning` nor remove any
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modules that have been scheduled for removal. Instead deprecated modules will
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just be *documented* as deprecated. Optionally modules may emit a
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`PendingDeprecationWarning`.
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All deprecated modules will also undergo a feature freeze. No additional
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features should be added. Bug should still be fixed.
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3.9
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---
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Starting with Python 3.9, deprecated modules will start issuing
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`DeprecationWarning`. The `parser`_ module is removed and potentially
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replaced with a new module.
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All other deprecated modules are fully supported and will receive security
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updates until Python 3.9 reaches its end of lifetime. Python 3.9.0 will
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be released about 18 months after 3.8.0 (April 2021?) and most likely
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be supported for 5 years after the release. The estimated EOL of Python 3.9
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is in 2026.
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3.10
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----
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In 3.10 all deprecated modules will be removed from the CPython repository
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together with tests, documentation, and autoconf rules.
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PEP acceptance process
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======================
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3.8.0b1 is scheduled to be release shortly after the PEP is officially
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submitted. Since it's improbable that the PEP will pass all stages of the
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PEP process in time, I propose a two step acceptance process that is
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analogous Python's two release deprecation process.
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The first *provisionally accepted* phase targets Python 3.8.0b1. In the first
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phase no code is changes or removed. Modules are only documented as
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deprecated. The only exception is the `parser`_ module. It has been
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documented as deprecated since Python 2.5 and is scheduled for removal for
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3.9 to make place for a more advanced parser.
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The final decision, which modules will be removed and how the removed code
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is preserved, can be delayed for another year.
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Deprecated modules
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==================
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The modules are grouped as data encoding, multimedia, network, OS interface,
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and misc modules. The majority of modules are for old data formats or
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old APIs. Some others are rarely useful and have better replacements on
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PyPI, e.g. Pillow for image processing or NumPy-based projects to deal with
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audio processing.
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.. csv-table:: Table 1: Proposed modules deprecations
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:header: "Module", "Deprecated in", "To be removed", "Has expert?", "Replacement"
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:widths: 1, 1, 1, 1, 2
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aifc,3.8,3.10,**yes (inactive)**,\-
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asynchat,**3.6**,3.10,**yes**,asyncio
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asyncore,**3.6**,3.10,**yes**,asyncio
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audioop,3.8,3.10,**yes**,\-
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binhex,3.8,3.10,no,\-
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cgi,3.8,3.10,no,\-
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cgitb,3.8,3.10,no,\-
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chunk,3.8,3.10,no,\-
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crypt,3.8,3.10,**yes (inactive)**,"bcrypt, argon2cffi, hashlib, passlib"
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formatter,3.4,3.10,no,\-
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fpectl,**3.7**,**3.7**,n/a,\-
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imghdr,3.8,3.10,no,"filetype, puremagic, python-magic"
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imp,**3.4**,3.10,**yes**,importlib
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macpath,**3.7**,**3.8**,n/a,\-
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msilib,3.8,3.10,no,\-
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nntplib,3.8,3.10,no,\-
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nis,3.8,3.10,no,\-
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ossaudiodev,3.8,3.10,no,\-
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parser,**2.5**,**3.9**,**yes**,"ast, lib2to3.pgen2"
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pipes,3.8,3.10,no,subprocess
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smtpd,"**3.4.7**, **3.5.4**",3.10,**yes**,aiosmtpd
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sndhdr,3.8,3.10,no,"filetype, puremagic, python-magic"
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spwd,3.8,3.10,no,"python-pam, simplepam"
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sunau,3.8,3.10,no,\-
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uu,3.8,3.10,no,\-
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xdrlib,3.8,3.10,no,\-
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Data encoding modules
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---------------------
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binhex
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~~~~~~
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The `binhex <https://docs.python.org/3/library/binhex.html>`_ module encodes
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and decodes Apple Macintosh binhex4 data. It was originally developed for
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TSR-80. In the 1980s and early 1990s it was used on classic Mac OS 9 to
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encode binary email attachments.
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Module type
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pure Python
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Deprecated in
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3.8
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To be removed in
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3.10
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Has a designated expert
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no
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Substitute
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**none**
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uu
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~~
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The `uu <https://docs.python.org/3/library/uu.html>`_ module provides
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uuencode format, an old binary encoding format for email from 1980. The uu
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format has been replaced by MIME. The uu codec is provided by the binascii
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module.
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Module type
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pure Python
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Deprecated in
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3.8
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To be removed in
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3.10
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Has a designated expert
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no
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Substitute
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**none**
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xdrlib
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~~~~~~
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The `xdrlib <https://docs.python.org/3/library/xdrlib.html>`_ module supports
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the Sun External Data Representation Standard. XDR is an old binary
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serialization format from 1987. These days it's rarely used outside
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specialized domains like NFS.
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Module type
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pure Python
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Deprecated in
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3.8
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To be removed in
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3.10
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Has a designated expert
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no
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Substitute
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**none**
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Multimedia modules
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------------------
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aifc
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~~~~
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The `aifc <https://docs.python.org/3/library/aifc.html>`_ module provides
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support for reading and writing AIFF and AIFF-C files. The Audio Interchange
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File Format is an old audio format from 1988 based on Amiga IFF. It was most
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commonly used on the Apple Macintosh. These days only few specialized
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application use AIFF.
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Module type
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pure Python (depends on `audioop`_ C extension)
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Deprecated in
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3.8
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To be removed in
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3.10
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Has a designated expert
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yes, but expert is currently inactive.
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Substitute
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**none**
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audioop
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~~~~~~~
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The `audioop <https://docs.python.org/3/library/audioop.html>`_ module
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contains helper functions to manipulate raw audio data and adaptive
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differential pulse-code modulated audio data. The module is implemented in
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C without any additional dependencies. The `aifc`_, `sunau`_, and `wave`_
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module depend on `audioop`_ for some operations. The byteswap operation in
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the `wave`_ module can be substituted with little work.
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Module type
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C extension
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Deprecated in
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3.8
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To be removed in
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3.10
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Has a designated expert
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yes
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Substitute
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**none**
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chunk
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~~~~~
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The `chunk <https://docs.python.org/3/library/chunk.html>`_ module provides
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support for reading and writing Electronic Arts' Interchange File Format.
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IFF is an old audio file format originally introduced for Commodore and
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Amiga. The format is no longer relevant.
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Module type
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pure Python
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Deprecated in
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3.8
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To be removed in
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3.10
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Has a designated expert
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no
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Substitute
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**none**
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imghdr
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~~~~~~
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The `imghdr <https://docs.python.org/3/library/imghdr.html>`_ module is a
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simple tool to guess the image file format from the first 32 bytes
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of a file or buffer. It supports only a limited amount of formats and
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neither returns resolution nor color depth.
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Module type
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pure Python
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Deprecated in
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3.8
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To be removed in
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3.10
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Has a designated expert
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no
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Substitute
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`puremagic <https://pypi.org/project/puremagic/>`_,
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`filetype <https://pypi.org/project/filetype/>`_,
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`python-magic <https://pypi.org/project/python-magic/>`_
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ossaudiodev
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~~~~~~~~~~~
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The `ossaudiodev <https://docs.python.org/3/library/ossaudiodev.html>`_
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module provides support for Open Sound System, an interface to sound
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playback and capture devices. OSS was initially free software, but later
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support for newer sound devices and improvements were proprietary. Linux
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community abandoned OSS in favor of ALSA [1]_. Some operation systems like
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OpenBSD and NetBSD provide an incomplete [2]_ emulation of OSS.
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Module type
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C extension
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Deprecated in
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3.8
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To be removed in
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3.10
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Has a designated expert
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no
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Substitute
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**none**
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sndhdr
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~~~~~~
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The `sndhdr <https://docs.python.org/3/library/sndhdr.html>`_ module is
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similar to the `imghdr`_ module but for audio formats. It guesses file
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format, channels, frame rate, and sample widths from the first 512 bytes of
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a file or buffer. The module only supports AU, AIFF, HCOM, VOC, WAV, and
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other ancient formats.
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Module type
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pure Python (depends on `audioop`_ C extension for some operations)
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Deprecated in
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3.8
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To be removed in
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3.10
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Has a designated expert
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no
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Substitute
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`puremagic <https://pypi.org/project/puremagic/>`_,
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`filetype <https://pypi.org/project/filetype/>`_,
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`python-magic <https://pypi.org/project/python-magic/>`_
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sunau
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~~~~~
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The `sunau <https://docs.python.org/3/library/sunhdr.html>`_ module provides
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support for Sun AU sound format. It's yet another old, obsolete file format.
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Module type
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pure Python (depends on `audioop`_ C extension for some operations)
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Deprecated in
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3.8
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To be removed in
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3.10
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Has a designated expert
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no
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Substitute
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**none**
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Networking modules
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------------------
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asynchat
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~~~~~~~~
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The `asynchat <https://docs.python.org/3/library/asynchat.html>`_ module
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is build on top of `asyncore`_ and has been deprecated since Python 3.6.
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Module type
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pure Python
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Deprecated in
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3.6
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Removed in
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3.10
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Has a designated expert
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yes
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Substitute
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asyncio
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asyncore
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~~~~~~~~
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The `asyncore <https://docs.python.org/3/library/asyncore.html>`_ module was
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the first module for asynchronous socket service clients and servers. It
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has been replaced by asyncio and is deprecated since Python 3.6.
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The ``asyncore`` module is also used in stdlib tests. The tests for
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``ftplib``, ``logging``, ``smptd``, ``smtplib``, and ``ssl`` are partly
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based on ``asyncore``. These tests must be updated to use asyncio or
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threading.
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Module type
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pure Python
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Deprecated in
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3.6
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Removed in
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3.10
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Has a designated expert
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yes
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Substitute
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asyncio
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cgi
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~~~
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The `cgi <https://docs.python.org/3/library/cgi.html>`_ module is a support
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module for Common Gateway Interface (CGI) scripts. CGI is deemed as
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inefficient because every incoming request is handled in a new process. PEP
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206 considers the module as *designed poorly and are now near-impossible
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to fix*.
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Several people proposed to either keep the cgi module for features like
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`cgi.parse_qs()` or move `cgi.escape()` to a different module. The
|
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functions `cgi.parse_qs` and `cgi.parse_qsl` have been
|
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deprecated for a while and are actually aliases for
|
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`urllib.parse.parse_qs` and `urllib.parse.parse_qsl`. The
|
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function `cgi.quote` has been deprecated in favor of `html.quote`
|
||
with secure default values.
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Module type
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pure Python
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Deprecated in
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3.8
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To be removed in
|
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3.10
|
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Has a designated expert
|
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no
|
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Substitute
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**none**
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||
|
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|
||
cgitb
|
||
~~~~~
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||
|
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The `cgitb <https://docs.python.org/3/library/cgitb.html>`_ module is a
|
||
helper for the cgi module for configurable tracebacks.
|
||
|
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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
|
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pure Python
|
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Deprecated in
|
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3.8
|
||
To be removed in
|
||
3.10
|
||
Has a designated expert
|
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no
|
||
Substitute
|
||
**none**
|
||
|
||
smtpd
|
||
~~~~~
|
||
|
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The `smtpd <https://docs.python.org/3/library/smtpd.html>`_ 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.
|
||
|
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Module type
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pure Python
|
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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 <https://docs.python.org/3/library/nntplib.html>`_ 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
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two decades, news has been slowly but steadily replaced with mailing lists
|
||
and web-based discussion platforms. Twisted is also
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`planning <https://twistedmatrix.com/trac/ticket/9405>`_ to deprecate NNTP
|
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support and `pynnt <https://github.com/greenbender/pynntp>`_ hasn't seen any
|
||
activity since 2014. This is a good indicator that the public interest in
|
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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 unavailble, too slow, or do
|
||
not work correctly over IPv6. The situation causes flaky test runs on
|
||
buildbots.
|
||
|
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Module type
|
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pure Python
|
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Deprecated in
|
||
3.8
|
||
To be removed in
|
||
3.10
|
||
Has a designated expert
|
||
no
|
||
Substitute
|
||
**none**
|
||
|
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|
||
Operating system interface
|
||
--------------------------
|
||
|
||
crypt
|
||
~~~~~
|
||
|
||
The `crypt <https://docs.python.org/3/library/crypt.html>`_ module implements
|
||
password hashing based on ``crypt(3)`` function from ``libcrypt`` or
|
||
``libxcrypt`` on Unix-like platform. 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 application need
|
||
an alternative implementation any way.
|
||
* Only DES encryption is guarenteed to be available. DES has an extremely
|
||
limited key space of 2**56.
|
||
* MD5, salted SHA256, salted SHA512, and Blowfish are optional extension.
|
||
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
|
||
`bcrypt <https://pypi.org/project/bcrypt/>`_,
|
||
`passlib <https://pypi.org/project/passlib/>`_,
|
||
`argon2cffi <https://pypi.org/project/argon2-cffi/>`_,
|
||
hashlib module (PBKDF2, scrypt)
|
||
|
||
macpath
|
||
~~~~~~~
|
||
|
||
The `macpath <https://docs.python.org/3/library/macpath.html>`_ 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 <https://docs.python.org/3/library/nis.html>`_ 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 <https://docs.python.org/3/library/spwd.html>`_ module provides
|
||
direct access to Unix shadow password database using non-standard APIs.
|
||
|
||
In general it's a bad idea to use the spwd. The spwd circumvents system
|
||
security policies, it 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 consider a *security bug*, as it bypasses
|
||
PAM's access control.
|
||
|
||
Further more the ``spwd`` module uses the
|
||
`shadow(3) <http://man7.org/linux/man-pages/man3/shadow.3.html>`_ 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 <https://pypi.org/project/python-pam/>`_,
|
||
`simpleplam <https://pypi.org/project/simplepam/>`_
|
||
|
||
Misc modules
|
||
------------
|
||
|
||
formatter
|
||
~~~~~~~~~
|
||
|
||
The `formatter <https://docs.python.org/3/library/formatter.html>`_ 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 <https://docs.python.org/3/library/imp.html>`_ module is the
|
||
predecessor of the
|
||
`importlib <https://docs.python.org/3/library/importlib.html>`_ 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 <https://docs.python.org/3/library/msilib.html>`_ 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
|
||
``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 <https://docs.python.org/3/library/parser.html>`_ module provides
|
||
an interface to Python’s internal parser and byte-code 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 <https://docs.python.org/3/library/pipes.html>`_ 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 <https://docs.python.org/3.6/library/fpectl.html>`_ 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 <https://bugs.python.org/issue29137>`_.
|
||
|
||
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 <https://docs.python.org/3/library/colorsys.html>`_ 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 <https://pypi.org/project/colormath/>`_,
|
||
`colour <https://pypi.org/project/colour/>`_
|
||
`colorspacious <https://pypi.org/project/colorspacious/>`_,
|
||
`Pillow <https://pypi.org/project/Pillow/>`_
|
||
|
||
fileinput
|
||
---------
|
||
|
||
The `fileinput <https://docs.python.org/3/library/fileinput.html>`_ module
|
||
implements a helpers to iterate over a list of files from ``sys.argv``. The
|
||
module predates the optparser and argparser module. 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 <https://docs.python.org/3/library/2to3.html>`_ 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 <https://docs.python.org/3/library/getopt.html>`_ 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 <https://docs.python.org/3/library/optparse.html>`_ 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 <https://docs.python.org/3/library/wave.html>`_ 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 the ``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 <https://github.com/tiran/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 in as binary
|
||
wheels with some effort. Other C modules can be replaced with ctypes or cffi.
|
||
For example I created `legacycrypt <https://github.com/tiran/legacycrypt>`_
|
||
with ``_crypt`` extension reimplemented with a few lines of ctypes code.
|
||
|
||
|
||
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 lifetime. 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 <https://pypi.org/project/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
|
||
|
||
|
||
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
|
||
|
||
|
||
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:
|