What’s New In Python 3.12

Release

3.12.0a0

Date

June 15, 2022

This article explains the new features in Python 3.12, compared to 3.11.

For full details, see the changelog.

Note

Prerelease users should be aware that this document is currently in draft form. It will be updated substantially as Python 3.12 moves towards release, so it’s worth checking back even after reading earlier versions.

Summary – Release highlights

Important deprecations, removals or restrictions:

• PEP 623, Remove wstr from Unicode

New Features

Other Language Changes

New Modules

• None yet.

Improved Modules

os

• Add os.PIDFD_NONBLOCK to open a file descriptor for a process with os.pidfd_open() in non-blocking mode. (Contributed by Kumar Aditya in gh-93312.)

Optimizations

• Removed wstr and wstr_length members from Unicode objects. It reduces object size by 8 or 16 bytes on 64bit platform. (PEP 623) (Contributed by Inada Naoki in gh-92536.)

CPython bytecode changes

• Removed the LOAD_METHOD instruction. It has been merged into LOAD_ATTR. LOAD_ATTR will now behave like the old LOAD_METHOD instruction if the low bit of its oparg is set. (Contributed by Ken Jin in gh-93429.)

Deprecated

Pending Removal in Python 3.13

The following modules and APIs have been deprecated in earlier Python releases, and will be removed in Python 3.13.

Modules (see PEP 594):

• aifc

• audioop

• cgi

• cgitb

• chunk

• crypt

• imghdr

• mailcap

• msilib

• nis

• nntplib

• ossaudiodev

• pipes

• sndhdr

• spwd

• sunau

• telnetlib

• uu

• xdrlib

APIs:

• configparser.LegacyInterpolation (gh-90765)

• locale.getdefaultlocale() (gh-90817)

• turtle.RawTurtle.settiltangle() (gh-50096)

• unittest.findTestCases() (gh-50096)

• unittest.makeSuite() (gh-50096)

• unittest.getTestCaseNames() (gh-50096)

• webbrowser.MacOSX (gh-86421)

Pending Removal in Future Versions

The following APIs were deprecated in earlier Python versions and will be removed, although there is currently no date scheduled for their removal.

• typing.Text (gh-92332)

• Currently Python accepts numeric literals immediately followed by keywords, for example 0in x, 1or x, 0if 1else 2. It allows confusing and ambiguous expressions like [0x1for x in y] (which can be interpreted as [0x1 for x in y] or [0x1f or x in y]). A syntax warning is raised if the numeric literal is immediately followed by one of keywords and, else, for, if, in, is and or. In a future release it will be changed to a syntax error. (gh-87999)

Removed

• The following undocumented sqlite3 features, deprecated in Python 3.10, are now removed:

  • sqlite3.enable_shared_cache()

  • sqlite3.OptimizedUnicode

  (Contributed by Erlend E. Aasland in gh-92548)

• The --experimental-isolated-subinterpreters configure flag (and corresponding EXPERIMENTAL_ISOLATED_SUBINTERPRETERS) have been removed.

Porting to Python 3.12

This section lists previously described changes and other bugfixes that may require changes to your code.

Changes in the Python API

• More strict rules are now applied for numerical group references and group names in regular expressions. Only sequence of ASCII digits is now accepted as a numerical reference. The group name in bytes patterns and replacement strings can now only contain ASCII letters and digits and underscore. (Contributed by Serhiy Storchaka in gh-91760.)

• Removed randrange() functionality deprecated since Python 3.10. Formerly, randrange(10.0) losslessly converted to randrange(10). Now, it raises a TypeError. Also, the exception raised for non-integral values such as randrange(10.5) or randrange(‘10’) has been changed from ValueError to TypeError. This also prevents bugs where randrange(1e25) would silently select from a larger range than randrange(10**25). (Originally suggested by Serhiy Storchaka gh-86388.)

Build Changes

• va_start() with two parameters, like va_start(args, format), is now required to build Python. va_start() is no longer called with a single parameter. (Contributed by Kumar Aditya in gh-93207.)

C API Changes

New Features

• Added the new limited C API function PyType_FromMetaclass(), which generalizes the existing PyType_FromModuleAndSpec() using an additional metaclass argument. (Contributed by Wenzel Jakob in gh-93012.)

Porting to Python 3.12

• Legacy Unicode APIs based on Py_UNICODE* representation has been removed. Please migrate to APIs based on UTF-8 or wchar_t*.

• Argument parsing functions like PyArg_ParseTuple() doesn’t support Py_UNICODE* based format (e.g. u, Z) anymore. Please migrate to other formats for Unicode like s, z, es, and U.

Deprecated

Removed

• Remove the token.h header file. There was never any public tokenizer C API. The token.h header file was only designed to be used by Python internals. (Contributed by Victor Stinner in gh-92651.)

• Leagcy Unicode APIs has been removed. See PEP 623 for detail.

  • PyUnicode_WCHAR_KIND

  • PyUnicode_AS_UNICODE()

  • PyUnicode_AsUnicode()

  • PyUnicode_AsUnicodeAndSize()

  • PyUnicode_AS_DATA()

  • PyUnicode_FromUnicode()

  • PyUnicode_GET_SIZE()

  • PyUnicode_GetSize()

  • PyUnicode_GET_DATA_SIZE()

• Remove the PyUnicode_InternImmortal() function and the SSTATE_INTERNED_IMMORTAL macro. (Contributed by Victor Stinner in gh-85858.)