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What's New In Python 3.12

Release:|release|
Date: |today|

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

For full details, see the :ref:`changelog <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

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`.)

Deprecated

Removed

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

    • sqlite3.enable_shared_cache()
    • sqlite3.OptimizedUnicode

    (Contributed by Erlend E. Aasland in :gh:`92548`)

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

C API Changes

New Features

  • Added the new limited C API function :c:func:`PyType_FromMetaclass`, which generalizes the existing :c:func:`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 :c:func:`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.

    • :c:macro:`PyUnicode_WCHAR_KIND`
    • :c:func:`PyUnicode_AS_UNICODE`
    • :c:func:`PyUnicode_AsUnicode`
    • :c:func:`PyUnicode_AsUnicodeAndSize`
    • :c:func:`PyUnicode_AS_DATA`
    • :c:func:`PyUnicode_FromUnicode`
    • :c:func:`PyUnicode_GET_SIZE`
    • :c:func:`PyUnicode_GetSize`
    • :c:func:`PyUnicode_GET_DATA_SIZE`

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