mirror of https://github.com/python/cpython
478 lines
18 KiB
ReStructuredText
478 lines
18 KiB
ReStructuredText
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****************************
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What's New In Python 3.12
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****************************
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:Release: |release|
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:Date: |today|
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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 bug/patch 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 :issue:`12345`.)
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This saves the maintainer the effort of going through the Mercurial log
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when researching a change.
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This article explains the new features in Python 3.12, compared to 3.11.
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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 3.12 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 3.12.
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Brevity is key.
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.. PEP-sized items next.
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Important deprecations, removals or restrictions:
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* :pep:`623`, Remove wstr from Unicode
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New Features
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============
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Other Language Changes
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======================
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* :class:`types.MappingProxyType` instances are now hashable if the underlying
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mapping is hashable.
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(Contributed by Serhiy Storchaka in :gh:`87995`.)
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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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dis
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---
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* Pseudo instruction opcodes (which are used by the compiler but
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do not appear in executable bytecode) are now exposed in the
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:mod:`dis` module.
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:data:`~dis.HAVE_ARGUMENT` is still relevant to real opcodes,
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but it is not useful for pseudo instrcutions. Use the new
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:data:`~dis.hasarg` collection instead.
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(Contributed by Irit Katriel in :gh:`94216`.)
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os
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--
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* Add :data:`os.PIDFD_NONBLOCK` to open a file descriptor
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for a process with :func:`os.pidfd_open` in non-blocking mode.
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(Contributed by Kumar Aditya in :gh:`93312`.)
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Optimizations
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=============
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* Removed ``wstr`` and ``wstr_length`` members from Unicode objects.
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It reduces object size by 8 or 16 bytes on 64bit platform. (:pep:`623`)
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(Contributed by Inada Naoki in :gh:`92536`.)
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CPython bytecode changes
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========================
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* Removed the :opcode:`LOAD_METHOD` instruction. It has been merged into
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:opcode:`LOAD_ATTR`. :opcode:`LOAD_ATTR` will now behave like the old
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:opcode:`LOAD_METHOD` instruction if the low bit of its oparg is set.
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(Contributed by Ken Jin in :gh:`93429`.)
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Deprecated
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==========
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* :class:`typing.Hashable` and :class:`typing.Sized` aliases for :class:`collections.abc.Hashable`
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and :class:`collections.abc.Sized`. (:gh:`94309`.)
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* The :mod:`sqlite3` :ref:`default adapters and converters
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<sqlite3-default-converters>` are now deprecated.
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Instead, use the :ref:`sqlite3-adapter-converter-recipes`
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and tailor them to your needs.
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(Contributed by Erlend E. Aasland in :gh:`90016`.)
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Pending Removal in Python 3.13
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------------------------------
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The following modules and APIs have been deprecated in earlier Python releases,
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and will be removed in Python 3.13.
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Modules (see :pep:`594`):
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* :mod:`aifc`
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* :mod:`audioop`
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* :mod:`cgi`
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* :mod:`cgitb`
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* :mod:`chunk`
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* :mod:`crypt`
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* :mod:`imghdr`
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* :mod:`mailcap`
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* :mod:`msilib`
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* :mod:`nis`
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* :mod:`nntplib`
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* :mod:`ossaudiodev`
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* :mod:`pipes`
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* :mod:`sndhdr`
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* :mod:`spwd`
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* :mod:`sunau`
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* :mod:`telnetlib`
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* :mod:`uu`
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* :mod:`xdrlib`
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APIs:
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* :class:`configparser.LegacyInterpolation` (:gh:`90765`)
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* :func:`locale.getdefaultlocale` (:gh:`90817`)
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* :meth:`turtle.RawTurtle.settiltangle` (:gh:`50096`)
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* :func:`unittest.findTestCases` (:gh:`50096`)
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* :func:`unittest.makeSuite` (:gh:`50096`)
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* :func:`unittest.getTestCaseNames` (:gh:`50096`)
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* :class:`webbrowser.MacOSX` (:gh:`86421`)
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Pending Removal in Python 3.14
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==============================
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* Deprecated the following :mod:`importlib.abc` classes, scheduled for removal in
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Python 3.14:
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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.TraversableResources`
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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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Pending Removal in Future Versions
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----------------------------------
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The following APIs were deprecated in earlier Python versions and will be removed,
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although there is currently no date scheduled for their removal.
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* :class:`typing.Text` (:gh:`92332`)
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* Currently Python accepts numeric literals immediately followed by keywords,
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for example ``0in x``, ``1or x``, ``0if 1else 2``. It allows confusing
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and ambiguous expressions like ``[0x1for x in y]`` (which can be
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interpreted as ``[0x1 for x in y]`` or ``[0x1f or x in y]``).
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A syntax warning is raised if the numeric literal is
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immediately followed by one of keywords :keyword:`and`, :keyword:`else`,
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:keyword:`for`, :keyword:`if`, :keyword:`in`, :keyword:`is` and :keyword:`or`.
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In a future release it will be changed to a syntax error. (:gh:`87999`)
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Removed
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=======
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* Removed many old deprecated :mod:`unittest` features:
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- A number of :class:`~unittest.TestCase` method aliases:
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============================ =============================== ===============
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Deprecated alias Method Name Deprecated in
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============================ =============================== ===============
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``failUnless`` :meth:`.assertTrue` 3.1
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``failIf`` :meth:`.assertFalse` 3.1
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``failUnlessEqual`` :meth:`.assertEqual` 3.1
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``failIfEqual`` :meth:`.assertNotEqual` 3.1
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``failUnlessAlmostEqual`` :meth:`.assertAlmostEqual` 3.1
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``failIfAlmostEqual`` :meth:`.assertNotAlmostEqual` 3.1
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``failUnlessRaises`` :meth:`.assertRaises` 3.1
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``assert_`` :meth:`.assertTrue` 3.2
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``assertEquals`` :meth:`.assertEqual` 3.2
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``assertNotEquals`` :meth:`.assertNotEqual` 3.2
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``assertAlmostEquals`` :meth:`.assertAlmostEqual` 3.2
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``assertNotAlmostEquals`` :meth:`.assertNotAlmostEqual` 3.2
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``assertRegexpMatches`` :meth:`.assertRegex` 3.2
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``assertRaisesRegexp`` :meth:`.assertRaisesRegex` 3.2
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``assertNotRegexpMatches`` :meth:`.assertNotRegex` 3.5
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============================ =============================== ===============
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You can use https://github.com/isidentical/teyit to automatically modernise
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your unit tests.
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- Undocumented and broken :class:`~unittest.TestCase` method
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``assertDictContainsSubset`` (deprecated in Python 3.2).
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- Undocumented :meth:`TestLoader.loadTestsFromModule
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<unittest.TestLoader.loadTestsFromModule>` parameter *use_load_tests*
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(deprecated and ignored since Python 3.2).
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- An alias of the :class:`~unittest.TextTestResult` class:
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``_TextTestResult`` (deprecated in Python 3.2).
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(Contributed by Serhiy Storchaka in :issue:`45162`.)
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* Several names deprecated in the :mod:`configparser` way back in 3.2 have
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been removed per :gh:`89336`:
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* :class:`configparser.ParsingError` no longer has a ``filename`` attribute
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or argument. Use the ``source`` attribute and argument instead.
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* :mod:`configparser` no longer has a ``SafeConfigParser`` class. Use the
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shorter :class:`~configparser.ConfigParser` name instead.
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* :class:`configparser.ConfigParser` no longer has a ``readfp`` method.
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Use :meth:`~configparser.ConfigParser.read_file` instead.
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* The following undocumented :mod:`sqlite3` features, deprecated in Python
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3.10, are now removed:
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* ``sqlite3.enable_shared_cache()``
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* ``sqlite3.OptimizedUnicode``
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If a shared cache must be used, open the database in URI mode using the
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``cache=shared`` query parameter.
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The ``sqlite3.OptimizedUnicode`` text factory has been an alias for
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:class:`str` since Python 3.3. Code that previously set the text factory to
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``OptimizedUnicode`` can either use ``str`` explicitly, or rely on the
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default value which is also ``str``.
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(Contributed by Erlend E. Aasland in :gh:`92548`.)
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* The ``--experimental-isolated-subinterpreters`` configure flag
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(and corresponding ``EXPERIMENTAL_ISOLATED_SUBINTERPRETERS``)
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have been removed.
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* Remove ``io.OpenWrapper`` and ``_pyio.OpenWrapper``, deprecated in Python
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3.10: just use :func:`open` instead. The :func:`open` (:func:`io.open`)
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function is a built-in function. Since Python 3.10, :func:`_pyio.open` is
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also a static method.
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(Contributed by Victor Stinner in :gh:`94169`.)
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* Remove the :func:`ssl.RAND_pseudo_bytes` function, deprecated in Python 3.6:
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use :func:`os.urandom` or :func:`ssl.RAND_bytes` instead.
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(Contributed by Victor Stinner in :gh:`94199`.)
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* :mod:`gzip`: Remove the ``filename`` attribute of :class:`gzip.GzipFile`,
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deprecated since Python 2.6, use the :attr:`~gzip.GzipFile.name` attribute
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instead. In write mode, the ``filename`` attribute added ``'.gz'`` file
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extension if it was not present.
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(Contributed by Victor Stinner in :gh:`94196`.)
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* Remove the :func:`ssl.match_hostname` function. The
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:func:`ssl.match_hostname` was deprecated in Python 3.7. OpenSSL performs
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hostname matching since Python 3.7, Python no longer uses the
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:func:`ssl.match_hostname` function.
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(Contributed by Victor Stinner in :gh:`94199`.)
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* Remove the :func:`locale.format` function, deprecated in Python 3.7:
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use :func:`locale.format_string` instead.
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(Contributed by Victor Stinner in :gh:`94226`.)
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* :mod:`hashlib`: Remove the pure Python implementation of
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:func:`hashlib.pbkdf2_hmac()`, deprecated in Python 3.10. Python 3.10 and
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newer requires OpenSSL 1.1.1 (:pep:`644`): this OpenSSL version provides
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a C implementation of :func:`~hashlib.pbkdf2_hmac()` which is faster.
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(Contributed by Victor Stinner in :gh:`94199`.)
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* :mod:`xml.etree`: Remove the ``ElementTree.Element.copy()`` method of the
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pure Python implementation, deprecated in Python 3.10, use the
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:func:`copy.copy` function instead. The C implementation of :mod:`xml.etree`
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has no ``copy()`` method, only a ``__copy__()`` method.
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(Contributed by Victor Stinner in :gh:`94383`.)
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* :mod:`zipimport`: Remove ``find_loader()`` and ``find_module()`` methods,
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deprecated in Python 3.10: use the ``find_spec()`` method instead. See
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:pep:`451` for the rationale.
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(Contributed by Victor Stinner in :gh:`94379`.)
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* Remove the :func:`ssl.wrap_socket` function, deprecated in Python 3.7:
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instead, create a :class:`ssl.SSLContext` object and call its
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:class:`ssl.SSLContext.wrap_socket` method. Any package that still uses
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:func:`ssl.wrap_socket` is broken and insecure. The function neither sends a
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SNI TLS extension nor validates server hostname. Code is subject to `CWE-295
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<https://cwe.mitre.org/data/definitions/295.html>`_: Improper Certificate
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Validation.
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(Contributed by Victor Stinner in :gh:`94199`.)
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Porting to Python 3.12
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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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* More strict rules are now applied for numerical group references and
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group names in regular expressions.
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Only sequence of ASCII digits is now accepted as a numerical reference.
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The group name in bytes patterns and replacement strings can now only
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contain ASCII letters and digits and underscore.
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(Contributed by Serhiy Storchaka in :gh:`91760`.)
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* Removed randrange() functionality deprecated since Python 3.10. Formerly,
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randrange(10.0) losslessly converted to randrange(10). Now, it raises a
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TypeError. Also, the exception raised for non-integral values such as
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randrange(10.5) or randrange('10') has been changed from ValueError to
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TypeError. This also prevents bugs where ``randrange(1e25)`` would silently
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select from a larger range than ``randrange(10**25)``.
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(Originally suggested by Serhiy Storchaka gh-86388.)
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* :class:`argparse.ArgumentParser` changed encoding and error handler
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for reading arguments from file (e.g. ``fromfile_prefix_chars`` option)
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from default text encoding (e.g. :func:`locale.getpreferredencoding(False) <locale.getpreferredencoding>`)
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to :term:`filesystem encoding and error handler`.
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Argument files should be encoded in UTF-8 instead of ANSI Codepage on Windows.
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* :func:`shlex.split`: Passing ``None`` for *s* argument now raises an
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exception, rather than reading :data:`sys.stdin`. The feature was deprecated
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in Python 3.9.
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(Contributed by Victor Stinner in :gh:`94352`.)
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Build Changes
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=============
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* Python no longer uses ``setup.py`` to build shared C extension modules.
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Build parameters like headers and libraries are detected in ``configure``
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script. Extensions are built by ``Makefile``. Most extensions use
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``pkg-config`` and fall back to manual detection.
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(Contributed by Christian Heimes in :gh:`93939`.)
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* ``va_start()`` with two parameters, like ``va_start(args, format),``
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is now required to build Python.
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``va_start()`` is no longer called with a single parameter.
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(Contributed by Kumar Aditya in :gh:`93207`.)
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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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* Added the new limited C API function :c:func:`PyType_FromMetaclass`,
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which generalizes the existing :c:func:`PyType_FromModuleAndSpec` using
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an additional metaclass argument.
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(Contributed by Wenzel Jakob in :gh:`93012`.)
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Porting to Python 3.12
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----------------------
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* Legacy Unicode APIs based on ``Py_UNICODE*`` representation has been removed.
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Please migrate to APIs based on UTF-8 or ``wchar_t*``.
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* Argument parsing functions like :c:func:`PyArg_ParseTuple` doesn't support
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``Py_UNICODE*`` based format (e.g. ``u``, ``Z``) anymore. Please migrate
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to other formats for Unicode like ``s``, ``z``, ``es``, and ``U``.
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* ``tp_weaklist`` for all static builtin types is always ``NULL``.
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This is an internal-only field on ``PyTypeObject``
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but we're pointing out the change in case someone happens to be
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accessing the field directly anyway. To avoid breakage, consider
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using the existing public C-API instead, or, if necessary, the
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(internal-only) ``_PyObject_GET_WEAKREFS_LISTPTR()`` macro.
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Deprecated
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----------
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* Deprecate global configuration variable:
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* :c:var:`Py_DebugFlag`: use :c:member:`PyConfig.parser_debug`
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* :c:var:`Py_VerboseFlag`: use :c:member:`PyConfig.verbose`
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* :c:var:`Py_QuietFlag`: use :c:member:`PyConfig.quiet`
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* :c:var:`Py_InteractiveFlag`: use :c:member:`PyConfig.interactive`
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* :c:var:`Py_InspectFlag`: use :c:member:`PyConfig.inspect`
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* :c:var:`Py_OptimizeFlag`: use :c:member:`PyConfig.optimization_level`
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* :c:var:`Py_NoSiteFlag`: use :c:member:`PyConfig.site_import`
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* :c:var:`Py_BytesWarningFlag`: use :c:member:`PyConfig.bytes_warning`
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* :c:var:`Py_FrozenFlag`: use :c:member:`PyConfig.pathconfig_warnings`
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* :c:var:`Py_IgnoreEnvironmentFlag`: use :c:member:`PyConfig.use_environment`
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* :c:var:`Py_DontWriteBytecodeFlag`: use :c:member:`PyConfig.write_bytecode`
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* :c:var:`Py_NoUserSiteDirectory`: use :c:member:`PyConfig.user_site_directory`
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* :c:var:`Py_UnbufferedStdioFlag`: use :c:member:`PyConfig.buffered_stdio`
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* :c:var:`Py_HashRandomizationFlag`: use :c:member:`PyConfig.use_hash_seed`
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and :c:member:`PyConfig.hash_seed`
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* :c:var:`Py_IsolatedFlag`: use :c:member:`PyConfig.isolated`
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* :c:var:`Py_LegacyWindowsFSEncodingFlag`: use :c:member:`PyConfig.legacy_windows_fs_encoding`
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* :c:var:`Py_LegacyWindowsStdioFlag`: use :c:member:`PyConfig.legacy_windows_stdio`
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* :c:var:`Py_FileSystemDefaultEncoding`: use :c:member:`PyConfig.filesystem_encoding`
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* :c:var:`Py_FileSystemDefaultEncodeErrors`: use :c:member:`PyConfig.filesystem_errors`
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* :c:var:`Py_UTF8Mode`: use :c:member:`PyPreConfig.utf8_mode` (see :c:func:`Py_PreInitialize`)
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The :c:func:`Py_InitializeFromConfig` API should be used with
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:c:type:`PyConfig` instead.
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(Contributed by Victor Stinner in :gh:`77782`.)
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Removed
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-------
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* Remove the ``token.h`` header file. There was never any public tokenizer C
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API. The ``token.h`` header file was only designed to be used by Python
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internals.
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(Contributed by Victor Stinner in :gh:`92651`.)
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* Leagcy Unicode APIs has been removed. See :pep:`623` for detail.
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* :c:macro:`PyUnicode_WCHAR_KIND`
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* :c:func:`PyUnicode_AS_UNICODE`
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* :c:func:`PyUnicode_AsUnicode`
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* :c:func:`PyUnicode_AsUnicodeAndSize`
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* :c:func:`PyUnicode_AS_DATA`
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* :c:func:`PyUnicode_FromUnicode`
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* :c:func:`PyUnicode_GET_SIZE`
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* :c:func:`PyUnicode_GetSize`
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* :c:func:`PyUnicode_GET_DATA_SIZE`
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* Remove the ``PyUnicode_InternImmortal()`` function and the
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``SSTATE_INTERNED_IMMORTAL`` macro.
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(Contributed by Victor Stinner in :gh:`85858`.)
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