**************************** What's new in Python 3.16 **************************** :Editor: TBD .. Rules for maintenance: * Anyone can add text to this document. Do not spend very much time on the wording of your changes, because your text will probably get rewritten to some degree. * The maintainer will go through Misc/NEWS periodically and add changes; it's therefore more important to add your changes to Misc/NEWS than to this file. * This is not a complete list of every single change; completeness is the purpose of Misc/NEWS. Some changes I consider too small or esoteric to include. If such a change is added to the text, I'll just remove it. (This is another reason you shouldn't spend too much time on writing your addition.) * If you want to draw your new text to the attention of the maintainer, add 'XXX' to the beginning of the paragraph or section. * It's OK to just add a fragmentary note about a change. For example: "XXX Describe the transmogrify() function added to the socket module." The maintainer will research the change and write the necessary text. * You can comment out your additions if you like, but it's not necessary (especially when a final release is some months away). * Credit the author of a patch or bugfix. Just the name is sufficient; the e-mail address isn't necessary. * It's helpful to add the issue number as a comment: XXX Describe the transmogrify() function added to the socket module. (Contributed by P.Y. Developer in :gh:`12345`.) This saves the maintainer the effort of going through the VCS log when researching a change. This article explains the new features in Python 3.16, compared to 3.15. For full details, see the :ref:`changelog `. .. note:: Prerelease users should be aware that this document is currently in draft form. It will be updated substantially as Python 3.16 moves towards release, so it's worth checking back even after reading earlier versions. Summary --- release highlights ============================== .. This section singles out the most important changes in Python 3.16. Brevity is key. .. PEP-sized items next. New features ============ Other language changes ====================== New modules =========== * None yet. Improved modules ================ gzip ---- * :func:`gzip.open` now accepts an optional argument ``mtime`` which is passed on to the constructor of the :class:`~gzip.GzipFile` class. (Contributed by Marin Misur in :gh:`91372`.) lzma ---- * Add support of new BCJ filters ARM64 and RISC-V via :const:`!lzma.FILTER_ARM64` and :const:`!lzma.FILTER_RISCV`. Note that the new filters will work only if runtime library supports them. ARM64 filter requires ``lzma`` 5.4.0 or newer while RISC-V requires 5.6.0 or newer. (Contributed by Chien Wong in :gh:`115988`.) os -- * Add :func:`os.pidfd_getfd` for duplicating a file descriptor from another process via a pidfd. Available on Linux 5.6+. (Contributed by Maurycy Pawłowski-Wieroński in :gh:`149464`.) xml --- * Add support for multiple multi-byte encodings in the :mod:`XML parser `: "cp932", "cp949", "cp950", "Big5","EUC-JP", "GB2312", "GBK", "johab", and "Shift_JIS". Add partial support (only BMP characters) for multi-byte encodings "Big5-HKSCS", "EUC_JIS-2004", "EUC_JISX0213", "Shift_JIS-2004", "Shift_JISX0213", "utf-8-sig" and non-standard aliases like "UTF8" (without hyphen). The parser now raises :exc:`ValueError` for known unsupported multi-byte encodings such us "ISO-2022-JP" or "raw-unicode-escape" instead of failing later, when encounter non-ASCII data. (Contributed by Serhiy Storchaka in :gh:`62259`.) .. Add improved modules above alphabetically, not here at the end. Optimizations ============= module_name ----------- * TODO Removed ======= annotationlib ------------- * The :meth:`!annotationlib.ForwardRef._evaluate` method which has been deprecated since Python 3.14. Use :meth:`annotationlib.ForwardRef.evaluate` or :func:`typing.evaluate_forward_ref` instead. array ----- * The ``'u'`` format code (:c:type:`wchar_t`) which has been deprecated in documentation since Python 3.3 and at runtime since Python 3.13. Use ``'w'`` format code instead (:c:type:`Py_UCS4`, always 4 bytes). asyncio ------- * The :func:`!asyncio.iscoroutinefunction` which has been deprecated since Python 3.14. Use :func:`inspect.iscoroutinefunction` instead. functools --------- * Calling the Python implementation of :func:`functools.reduce` with *function* or *sequence* as keyword arguments has been deprecated since Python 3.14. logging ------- * Support for custom logging handlers with the *strm* argument is deprecated and scheduled for removal in Python 3.16. Define handlers with the *stream* argument instead. mimetypes --------- * Valid extensions start with a '.' or are empty for :meth:`mimetypes.MimeTypes.add_type`. Undotted extensions now raise a :exc:`ValueError`. shutil ------ * The :exc:`!ExecError` exception which has been deprecated since Python 3.14. It has not been used by any function in :mod:`!shutil` since Python 3.4. (Contributed by Stan Ulbrych in :gh:`149567`.) symtable -------- * The :meth:`!symtable.Class.get_methods` method which has been deprecated since Python 3.14. sys --- * The :func:`!_enablelegacywindowsfsencoding` function which has been deprecated since Python 3.13. Use the :envvar:`PYTHONLEGACYWINDOWSFSENCODING` environment variable instead. (Contributed by Stan Ulbrych in :gh:`149595`.) sysconfig --------- * The :func:`!sysconfig.expand_makefile_vars` function which has been deprecated since Python 3.14. Use the ``vars`` argument of :func:`sysconfig.get_paths` instead. (Contributed by Stan Ulbrych in :gh:`149499`.) tarfile ------- * The undocumented and unused :attr:`!tarfile.TarFile.tarfile` attribute has been deprecated since Python 3.13. .. Add removals above alphabetically, not here at the end. Deprecated ========== * :mod:`abc` * Soft-deprecated since Python 3.3 :class:`abc.abstractclassmethod`, :class:`abc.abstractstaticmethod`, and :class:`abc.abstractproperty` now raise a :exc:`DeprecationWarning`. These classes will be removed in Python 3.21, instead use :func:`abc.abstractmethod` with :func:`classmethod`, :func:`staticmethod`, and :class:`property` respectively. * :mod:`ast`: * Classes ``slice``, ``Index``, ``ExtSlice``, ``Suite``, ``Param``, ``AugLoad`` and ``AugStore``, deprecated since Python 3.9, are no longer imported by ``from ast import *`` and issue a deprecation warning on use. The classes are slated for removal in Python 3.21. These types are not generated by the parser or accepted by the code generator. * The ``dims`` property of ``ast.Tuple`` objects, deprecated since Python 3.9, now issues a deprecation warning on use. This property is slated for removal in 3.21. Use ``ast.Tuple.elts`` instead. .. Add deprecations above alphabetically, not here at the end. .. include:: ../deprecations/pending-removal-in-3.17.rst .. include:: ../deprecations/pending-removal-in-3.19.rst .. include:: ../deprecations/pending-removal-in-3.20.rst .. include:: ../deprecations/pending-removal-in-future.rst Porting to Python 3.16 ====================== This section lists previously described changes and other bugfixes that may require changes to your code. Build changes ============= * Remove the bundled copy of the libmpdec_ decimal library from the CPython source tree to simplify maintenence and updates. The :mod:`decimal` module will now unconditionally use the system's libmpdec decimal library. Also remove the now unused :option:`!--with-system-libmpdec` :program:`configure` flag. This change has no impact on binary releases of Python, which have been built against a separate copy of libmpdec for the past several releases. (Contributed by Sergey B Kirpichev in :gh:`115119`.) .. _libmpdec: https://www.bytereef.org/mpdecimal/ * Add a :option:`--with-build-details-suffix` configure flag to allow Linux distributions that co-install multiple versions of Python in the same tree to avoid ``build-details.json`` clashes. (Contributed by Stefano Rivera in :gh:`131372`.) C API changes ============= New features ------------ * TODO Porting to Python 3.16 ---------------------- * TODO Deprecated C APIs ----------------- * TODO .. Add C API deprecations above alphabetically, not here at the end. Removed C APIs --------------