mirror of https://github.com/python/cpython
586 lines
18 KiB
ReStructuredText
586 lines
18 KiB
ReStructuredText
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****************************
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What's New In Python 3.14
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****************************
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:Editor: TBD
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.. Rules for maintenance:
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* Anyone can add text to this document. Do not spend very much time
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on the wording of your changes, because your text will probably
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get rewritten to some degree.
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* The maintainer will go through Misc/NEWS periodically and add
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changes; it's therefore more important to add your changes to
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Misc/NEWS than to this file.
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* This is not a complete list of every single change; completeness
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is the purpose of Misc/NEWS. Some changes I consider too small
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or esoteric to include. If such a change is added to the text,
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I'll just remove it. (This is another reason you shouldn't spend
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too much time on writing your addition.)
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* If you want to draw your new text to the attention of the
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maintainer, add 'XXX' to the beginning of the paragraph or
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section.
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* It's OK to just add a fragmentary note about a change. For
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example: "XXX Describe the transmogrify() function added to the
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socket module." The maintainer will research the change and
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write the necessary text.
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* You can comment out your additions if you like, but it's not
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necessary (especially when a final release is some months away).
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* Credit the author of a patch or bugfix. Just the name is
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sufficient; the e-mail address isn't necessary.
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* It's helpful to add the issue number as a comment:
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XXX Describe the transmogrify() function added to the socket
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module.
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(Contributed by P.Y. Developer in :gh:`12345`.)
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This saves the maintainer the effort of going through the VCS log
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when researching a change.
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This article explains the new features in Python 3.14, compared to 3.13.
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For full details, see the :ref:`changelog <changelog>`.
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.. note::
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Prerelease users should be aware that this document is currently in draft
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form. It will be updated substantially as Python 3.14 moves towards release,
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so it's worth checking back even after reading earlier versions.
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Summary -- Release highlights
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=============================
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.. This section singles out the most important changes in Python 3.14.
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Brevity is key.
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.. PEP-sized items next.
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New Features
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============
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Improved Error Messages
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-----------------------
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* When unpacking assignment fails due to incorrect number of variables, the
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error message prints the received number of values in more cases than before.
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(Contributed by Tushar Sadhwani in :gh:`122239`.)
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.. code-block:: pycon
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>>> x, y, z = 1, 2, 3, 4
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Traceback (most recent call last):
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File "<stdin>", line 1, in <module>
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x, y, z = 1, 2, 3, 4
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^^^^^^^
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ValueError: too many values to unpack (expected 3, got 4)
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Other Language Changes
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======================
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* Incorrect usage of :keyword:`await` and asynchronous comprehensions
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is now detected even if the code is optimized away by the :option:`-O`
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command line option. For example, ``python -O -c 'assert await 1'``
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now produces a :exc:`SyntaxError`. (Contributed by Jelle Zijlstra in :gh:`121637`.)
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* Writes to ``__debug__`` are now detected even if the code is optimized
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away by the :option:`-O` command line option. For example,
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``python -O -c 'assert (__debug__ := 1)'`` now produces a
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:exc:`SyntaxError`. (Contributed by Irit Katriel in :gh:`122245`.)
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* Added class methods :meth:`float.from_number` and :meth:`complex.from_number`
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to convert a number to :class:`float` or :class:`complex` type correspondingly.
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They raise an error if the argument is a string.
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(Contributed by Serhiy Storchaka in :gh:`84978`.)
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New Modules
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===========
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* None yet.
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Improved Modules
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================
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ast
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---
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* Added :func:`ast.compare` for comparing two ASTs.
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(Contributed by Batuhan Taskaya and Jeremy Hylton in :issue:`15987`.)
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* Add support for :func:`copy.replace` for AST nodes.
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(Contributed by Bénédikt Tran in :gh:`121141`.)
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* Docstrings are now removed from an optimized AST in optimization level 2.
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(Contributed by Irit Katriel in :gh:`123958`.)
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ctypes
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------
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* The layout of :ref:`bit fields <ctypes-bit-fields-in-structures-unions>`
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in :class:`~ctypes.Structure` and :class:`~ctypes.Union`
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now matches platform defaults (GCC/Clang or MVSC) more closely.
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In particular, fields no longer overlap.
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(Contributed by Matthias Görgens in :gh:`97702`.)
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* The :attr:`.Structure._layout_` class attribute can now be set
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to help match a non-default ABI.
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(Contributed by Petr Viktorin in :gh:`97702`.)
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dis
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---
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* Added support for rendering full source location information of
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:class:`instructions <dis.Instruction>`, rather than only the line number.
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This feature is added to the following interfaces via the ``show_positions``
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keyword argument:
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- :class:`dis.Bytecode`,
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- :func:`dis.dis`, :func:`dis.distb`, and
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- :func:`dis.disassemble`.
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This feature is also exposed via :option:`dis --show-positions`.
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(Contributed by Bénédikt Tran in :gh:`123165`.)
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fractions
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---------
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Added support for converting any objects that have the
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:meth:`!as_integer_ratio` method to a :class:`~fractions.Fraction`.
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(Contributed by Serhiy Storchaka in :gh:`82017`.)
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http
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----
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Directory lists and error pages generated by the :mod:`http.server`
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module allow the browser to apply its default dark mode.
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(Contributed by Yorik Hansen in :gh:`123430`.)
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json
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----
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Add notes for JSON serialization errors that allow to identify the source
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of the error.
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(Contributed by Serhiy Storchaka in :gh:`122163`.)
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Enable :mod:`json` module to work as a script using the :option:`-m` switch: ``python -m json``.
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See the :ref:`JSON command-line interface <json-commandline>` documentation.
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(Contributed by Trey Hunner in :gh:`122873`.)
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operator
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--------
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* Two new functions ``operator.is_none`` and ``operator.is_not_none``
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have been added, such that ``operator.is_none(obj)`` is equivalent
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to ``obj is None`` and ``operator.is_not_none(obj)`` is equivalent
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to ``obj is not None``.
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(Contributed by Raymond Hettinger and Nico Mexis in :gh:`115808`.)
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os
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--
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* Added the :data:`os.environ.refresh() <os.environ>` method to update
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:data:`os.environ` with changes to the environment made by :func:`os.putenv`,
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by :func:`os.unsetenv`, or made outside Python in the same process.
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(Contributed by Victor Stinner in :gh:`120057`.)
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pathlib
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-------
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* Add methods to :class:`pathlib.Path` to recursively copy or move files and
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directories:
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* :meth:`~pathlib.Path.copy` copies a file or directory tree to a destination.
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* :meth:`~pathlib.Path.copy_into` copies *into* a destination directory.
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* :meth:`~pathlib.Path.move` moves a file or directory tree to a destination.
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* :meth:`~pathlib.Path.move_into` moves *into* a destination directory.
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(Contributed by Barney Gale in :gh:`73991`.)
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pdb
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---
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* Hard-coded breakpoints (:func:`breakpoint` and :func:`pdb.set_trace`) now
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reuse the most recent :class:`~pdb.Pdb` instance that calls
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:meth:`~pdb.Pdb.set_trace`, instead of creating a new one each time.
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As a result, all the instance specific data like :pdbcmd:`display` and
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:pdbcmd:`commands` are preserved across hard-coded breakpoints.
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(Contributed by Tian Gao in :gh:`121450`.)
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pickle
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------
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* Set the default protocol version on the :mod:`pickle` module to 5.
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For more details, please see :ref:`pickle protocols <pickle-protocols>`.
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* Add notes for pickle serialization errors that allow to identify the source
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of the error.
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(Contributed by Serhiy Storchaka in :gh:`122213`.)
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symtable
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--------
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* Expose the following :class:`symtable.Symbol` methods:
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* :meth:`~symtable.Symbol.is_free_class`
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* :meth:`~symtable.Symbol.is_comp_iter`
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* :meth:`~symtable.Symbol.is_comp_cell`
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(Contributed by Bénédikt Tran in :gh:`120029`.)
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.. Add improved modules above alphabetically, not here at the end.
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Optimizations
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=============
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asyncio
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-------
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* :mod:`asyncio` now uses double linked list implementation for native tasks
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which speeds up execution by 10% on standard pyperformance benchmarks and
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reduces memory usage.
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(Contributed by Kumar Aditya in :gh:`107803`.)
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Deprecated
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==========
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* :mod:`builtins`:
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Passing a complex number as the *real* or *imag* argument in the
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:func:`complex` constructor is now deprecated; it should only be passed
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as a single positional argument.
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(Contributed by Serhiy Storchaka in :gh:`109218`.)
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* :mod:`os`:
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:term:`Soft deprecate <soft deprecated>` :func:`os.popen` and
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:func:`os.spawn* <os.spawnl>` functions. They should no longer be used to
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write new code. The :mod:`subprocess` module is recommended instead.
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(Contributed by Victor Stinner in :gh:`120743`.)
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* :mod:`symtable`:
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Deprecate :meth:`symtable.Class.get_methods` due to the lack of interest.
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(Contributed by Bénédikt Tran in :gh:`119698`.)
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.. Add deprecations above alphabetically, not here at the end.
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.. include:: ../deprecations/pending-removal-in-3.15.rst
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.. include:: ../deprecations/pending-removal-in-3.16.rst
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.. include:: ../deprecations/pending-removal-in-future.rst
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Removed
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=======
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argparse
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--------
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* Remove the *type*, *choices*, and *metavar* parameters
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of :class:`!argparse.BooleanOptionalAction`.
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They were deprecated since 3.12.
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ast
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---
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* Remove the following classes. They were all deprecated since Python 3.8,
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and have emitted deprecation warnings since Python 3.12:
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* :class:`!ast.Num`
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* :class:`!ast.Str`
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* :class:`!ast.Bytes`
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* :class:`!ast.NameConstant`
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* :class:`!ast.Ellipsis`
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Use :class:`ast.Constant` instead. As a consequence of these removals,
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user-defined ``visit_Num``, ``visit_Str``, ``visit_Bytes``,
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``visit_NameConstant`` and ``visit_Ellipsis`` methods on custom
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:class:`ast.NodeVisitor` subclasses will no longer be called when the
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``NodeVisitor`` subclass is visiting an AST. Define a ``visit_Constant``
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method instead.
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Also, remove the following deprecated properties on :class:`ast.Constant`,
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which were present for compatibility with the now-removed AST classes:
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* :attr:`!ast.Constant.n`
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* :attr:`!ast.Constant.s`
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Use :attr:`!ast.Constant.value` instead.
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(Contributed by Alex Waygood in :gh:`119562`.)
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asyncio
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-------
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* Remove the following classes and functions. They were all deprecated and
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emitted deprecation warnings since Python 3.12:
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* :class:`!asyncio.AbstractChildWatcher`
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* :class:`!asyncio.SafeChildWatcher`
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* :class:`!asyncio.MultiLoopChildWatcher`
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* :class:`!asyncio.FastChildWatcher`
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* :class:`!asyncio.ThreadedChildWatcher`
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* :class:`!asyncio.PidfdChildWatcher`
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* :meth:`!asyncio.AbstractEventLoopPolicy.get_child_watcher`
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* :meth:`!asyncio.AbstractEventLoopPolicy.set_child_watcher`
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* :func:`!asyncio.get_child_watcher`
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* :func:`!asyncio.set_child_watcher`
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(Contributed by Kumar Aditya in :gh:`120804`.)
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collections.abc
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---------------
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* Remove :class:`!collections.abc.ByteString`. It had previously raised a
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:exc:`DeprecationWarning` since Python 3.12.
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email
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-----
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* Remove the *isdst* parameter from :func:`email.utils.localtime`.
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(Contributed by Hugo van Kemenade in :gh:`118798`.)
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importlib
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---------
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* Remove deprecated :mod:`importlib.abc` classes:
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* :class:`!importlib.abc.ResourceReader`
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* :class:`!importlib.abc.Traversable`
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* :class:`!importlib.abc.TraversableResources`
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Use :mod:`importlib.resources.abc` classes instead:
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* :class:`importlib.resources.abc.Traversable`
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* :class:`importlib.resources.abc.TraversableResources`
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(Contributed by Jason R. Coombs and Hugo van Kemenade in :gh:`93963`.)
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itertools
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---------
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* Remove :mod:`itertools` support for copy, deepcopy, and pickle operations.
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These had previously raised a :exc:`DeprecationWarning` since Python 3.12.
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(Contributed by Raymond Hettinger in :gh:`101588`.)
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pathlib
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-------
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* Remove support for passing additional keyword arguments to
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:class:`pathlib.Path`. In previous versions, any such arguments are ignored.
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* Remove support for passing additional positional arguments to
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:meth:`pathlib.PurePath.relative_to` and
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:meth:`~pathlib.PurePath.is_relative_to`. In previous versions, any such
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arguments are joined onto *other*.
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pty
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---
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* Remove deprecated :func:`!pty.master_open` and :func:`!pty.slave_open`.
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They had previously raised a :exc:`DeprecationWarning` since Python 3.12.
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Use :func:`pty.openpty` instead.
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(Contributed by Nikita Sobolev in :gh:`118824`.)
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sqlite3
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-------
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* Remove :data:`!version` and :data:`!version_info` from :mod:`sqlite3`.
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(Contributed by Hugo van Kemenade in :gh:`118924`.)
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* Disallow using a sequence of parameters with named placeholders.
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This had previously raised a :exc:`DeprecationWarning` since Python 3.12;
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it will now raise a :exc:`sqlite3.ProgrammingError`.
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(Contributed by Erlend E. Aasland in :gh:`118928` and :gh:`101693`.)
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typing
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------
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* Remove :class:`!typing.ByteString`. It had previously raised a
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:exc:`DeprecationWarning` since Python 3.12.
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urllib
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------
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* Remove deprecated :class:`!Quoter` class from :mod:`urllib.parse`.
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It had previously raised a :exc:`DeprecationWarning` since Python 3.11.
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(Contributed by Nikita Sobolev in :gh:`118827`.)
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Others
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------
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* Using :data:`NotImplemented` in a boolean context will now raise a :exc:`TypeError`.
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It had previously raised a :exc:`DeprecationWarning` since Python 3.9. (Contributed
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by Jelle Zijlstra in :gh:`118767`.)
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* The :func:`int` built-in no longer delegates to
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:meth:`~object.__trunc__`. Classes that want to support conversion to
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integer must implement either :meth:`~object.__int__` or
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:meth:`~object.__index__`. (Contributed by Mark Dickinson in :gh:`119743`.)
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Porting to Python 3.14
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======================
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This section lists previously described changes and other bugfixes
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that may require changes to your code.
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Changes in the Python API
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-------------------------
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* :class:`functools.partial` is now a method descriptor.
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Wrap it in :func:`staticmethod` if you want to preserve the old behavior.
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(Contributed by Serhiy Storchaka and Dominykas Grigonis in :gh:`121027`.)
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Build Changes
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=============
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C API Changes
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=============
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New Features
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------------
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* Add :c:func:`PyLong_GetSign` function to get the sign of :class:`int` objects.
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(Contributed by Sergey B Kirpichev in :gh:`116560`.)
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* Add a new :c:type:`PyUnicodeWriter` API to create a Python :class:`str`
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object:
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* :c:func:`PyUnicodeWriter_Create`.
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* :c:func:`PyUnicodeWriter_Discard`.
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* :c:func:`PyUnicodeWriter_Finish`.
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* :c:func:`PyUnicodeWriter_WriteChar`.
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* :c:func:`PyUnicodeWriter_WriteUTF8`.
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* :c:func:`PyUnicodeWriter_WriteUCS4`.
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* :c:func:`PyUnicodeWriter_WriteWideChar`.
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* :c:func:`PyUnicodeWriter_WriteStr`.
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* :c:func:`PyUnicodeWriter_WriteRepr`.
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* :c:func:`PyUnicodeWriter_WriteSubstring`.
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* :c:func:`PyUnicodeWriter_Format`.
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* :c:func:`PyUnicodeWriter_DecodeUTF8Stateful`.
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(Contributed by Victor Stinner in :gh:`119182`.)
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* Add :c:func:`PyIter_NextItem` to replace :c:func:`PyIter_Next`,
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which has an ambiguous return value.
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(Contributed by Irit Katriel and Erlend Aasland in :gh:`105201`.)
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* :c:func:`Py_Finalize` now deletes all interned strings. This
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is backwards incompatible to any C-Extension that holds onto an interned
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string after a call to :c:func:`Py_Finalize` and is then reused after a
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call to :c:func:`Py_Initialize`. Any issues arising from this behavior will
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normally result in crashes during the exectuion of the subsequent call to
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:c:func:`Py_Initialize` from accessing uninitialized memory. To fix, use
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an address sanitizer to identify any use-after-free coming from
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an interned string and deallocate it during module shutdown.
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(Contribued by Eddie Elizondo in :gh:`113601`.)
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* Add new functions to convert C ``<stdint.h>`` numbers from/to Python
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:class:`int`:
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* :c:func:`PyLong_FromInt32`
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* :c:func:`PyLong_FromInt64`
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* :c:func:`PyLong_FromUInt32`
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* :c:func:`PyLong_FromUInt64`
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* :c:func:`PyLong_AsInt32`
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* :c:func:`PyLong_AsInt64`
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* :c:func:`PyLong_AsUInt32`
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* :c:func:`PyLong_AsUInt64`
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(Contributed by Victor Stinner in :gh:`120389`.)
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* Add :c:func:`PyBytes_Join(sep, iterable) <PyBytes_Join>` function,
|
|
similar to ``sep.join(iterable)`` in Python.
|
|
(Contributed by Victor Stinner in :gh:`121645`.)
|
|
|
|
* Add :c:func:`Py_HashBuffer` to compute and return the hash value of a buffer.
|
|
(Contributed by Antoine Pitrou and Victor Stinner in :gh:`122854`.)
|
|
|
|
* Add functions to get and set the current runtime Python configuration
|
|
(:pep:`741`):
|
|
|
|
* :c:func:`PyConfig_Get`
|
|
* :c:func:`PyConfig_GetInt`
|
|
* :c:func:`PyConfig_Set`
|
|
* :c:func:`PyConfig_Names`
|
|
|
|
(Contributed by Victor Stinner in :gh:`107954`.)
|
|
|
|
* Add functions to configure the Python initialization (:pep:`741`):
|
|
|
|
* :c:func:`PyInitConfig_Create`
|
|
* :c:func:`PyInitConfig_Free`
|
|
* :c:func:`PyInitConfig_GetError`
|
|
* :c:func:`PyInitConfig_GetExitCode`
|
|
* :c:func:`PyInitConfig_HasOption`
|
|
* :c:func:`PyInitConfig_GetInt`
|
|
* :c:func:`PyInitConfig_GetStr`
|
|
* :c:func:`PyInitConfig_GetStrList`
|
|
* :c:func:`PyInitConfig_FreeStrList`
|
|
* :c:func:`PyInitConfig_SetInt`
|
|
* :c:func:`PyInitConfig_SetStr`
|
|
* :c:func:`PyInitConfig_SetStrList`
|
|
* :c:func:`PyInitConfig_AddModule`
|
|
* :c:func:`Py_InitializeFromInitConfig`
|
|
|
|
(Contributed by Victor Stinner in :gh:`107954`.)
|
|
|
|
|
|
Porting to Python 3.14
|
|
----------------------
|
|
|
|
* In the limited C API 3.14 and newer, :c:func:`Py_TYPE` is now implemented as
|
|
an opaque function call to hide implementation details.
|
|
(Contributed by Victor Stinner in :gh:`120600`.)
|
|
|
|
|
|
Deprecated
|
|
----------
|
|
|
|
* Macros :c:macro:`!Py_IS_NAN`, :c:macro:`!Py_IS_INFINITY`
|
|
and :c:macro:`!Py_IS_FINITE` are :term:`soft deprecated`,
|
|
use instead :c:macro:`!isnan`, :c:macro:`!isinf` and
|
|
:c:macro:`!isfinite` available from :file:`math.h`
|
|
since C99. (Contributed by Sergey B Kirpichev in :gh:`119613`.)
|
|
|
|
* :func:`!asyncio.iscoroutinefunction` is deprecated
|
|
and will be removed in Python 3.16,
|
|
use :func:`inspect.iscoroutinefunction` instead.
|
|
(Contributed by Jiahao Li and Kumar Aditya in :gh:`122875`.)
|
|
|
|
.. Add deprecations above alphabetically, not here at the end.
|
|
|
|
.. include:: ../deprecations/c-api-pending-removal-in-3.15.rst
|
|
|
|
.. include:: ../deprecations/c-api-pending-removal-in-future.rst
|
|
|
|
Removed
|
|
-------
|
|
|
|
* Creating :c:data:`immutable types <Py_TPFLAGS_IMMUTABLETYPE>` with mutable
|
|
bases was deprecated since 3.12 and now raises a :exc:`TypeError`.
|