PEP 594 – Removing dead batteries from Python's standard library

Thebinhex module encodes and decodes Apple Macintosh binhex4 data. It was originally developed for TSR-80. In the 1980s and early 1990s it was used on classic Mac OS 9 to encode binary email attachments.

Theuu 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 The uu format has been replaced by MIME.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.

Thexdrlib 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.

Theaifc 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.

Theaudioop 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. Theaifc , sunau , andwave module depend onaudioop for some operations. The byteswap operation in thewave module can be substituted with little work.

Thechunk 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.

Theimghdr 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 amount of formats and neither returns resolution nor color depth.

Theossaudiodev 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. Some operation systems like OpenBSD and NetBSD provide an incompleteemulation of OSS.

Thesndhdr module is similar to theimghdr 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.

Thesunau module provides support for Sun AU sound format. It's yet another old, obsolete file format.

Theasynchat module is build on top ofasyncore and has been deprecated since Python 3.6.

Theasyncore 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.

Thecgi 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 .

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.

Thecgitb 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.

Thesmtpd 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.

Thenntplib 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 pynnt 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 unavailble, too slow, or do not work correctly over IPv6. The situation causes flaky test runs on buildbots.

Thecrypt 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), seespwd deprecation.

Themacpath module provides Mac OS 9 implementation of os.path routines. Mac OS 9 is no longer supported

Thenis 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.

Thespwd 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) 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.

Theformatter module is an old text formatting module which has been deprecated since Python 3.4.

Theimp module is the predecessor of theimportlib module. Most functions have been deprecated since Python 3.3 and the module since Python 3.4.

Themsilib 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.

Theparser 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.

Most importantly the presence of the parser module makes it harder to switch to something more powerful than a LL(1) parser. 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.

Thepipes 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.