3.13.rst

What's New In Python 3.13

Release:	|release|
Date:	|today|

This article explains the new features in Python 3.13, compared to 3.12.

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 3.13 moves towards release, so it's worth checking back even after reading earlier versions.

Summary -- Release highlights

New Features

Other Language Changes

• Allow the count argument of :meth:`str.replace` to be a keyword. (Contributed by Hugo van Kemenade in :gh:`106487`.)

New Modules

• None yet.

Improved Modules

array

• Add 'w' type code (Py_UCS4) that can be used for Unicode strings. It can be used instead of 'u' type code, which is deprecated. (Contributed by Inada Naoki in :gh:`80480`.)

io

The :class:`io.IOBase` finalizer now logs the close() method errors with :data:`sys.unraisablehook`. Previously, errors were ignored silently by default, and only logged in :ref:`Python Development Mode <devmode>` or on :ref:`Python built on debug mode <debug-build>`. (Contributed by Victor Stinner in :gh:`62948`.)

pathlib

• Add :exc:`pathlib.UnsupportedOperation`, which is raised instead of :exc:`NotImplementedError` when a path operation isn't supported. (Contributed by Barney Gale in :gh:`89812`.)
• Add support for recursive wildcards in :meth:`pathlib.PurePath.match`. (Contributed by Barney Gale in :gh:`73435`.)
• Add follow_symlinks keyword-only argument to :meth:`pathlib.Path.glob`, :meth:`~pathlib.Path.rglob`, :meth:`~pathlib.Path.is_file`, and :meth:`~pathlib.Path.is_dir`. (Contributed by Barney Gale in :gh:`77609` and :gh:`105793`.)

traceback

• Add show_group paramter to :func:`traceback.TracebackException.format_exception_only` to format the nested exceptions of a :exc:`BaseExceptionGroup` instance, recursively. (Contributed by Irit Katriel in :gh:`105292`.)

typing

• Add :func:`typing.get_protocol_members` to return the set of members defining a :class:`typing.Protocol`. Add :func:`typing.is_protocol` to check whether a class is a :class:`typing.Protocol`. (Contributed by Jelle Zijlstra in :gh:`104873`.)

Optimizations

Deprecated

• :mod:`wave`: Deprecate the getmark(), setmark() and getmarkers() methods of the :class:`wave.Wave_read` and :class:`wave.Wave_write` classes. They will be removed in Python 3.15. (Contributed by Victor Stinner in :gh:`105096`.)
• :mod:`typing`: Creating a :class:`typing.NamedTuple` class using keyword arguments to denote the fields (NT = NamedTuple("NT", x=int, y=int)) is deprecated, and will be disallowed in Python 3.15. Use the class-based syntax or the functional syntax instead. (Contributed by Alex Waygood in :gh:`105566`.)
• :mod:`typing`: When using the functional syntax to create a :class:`typing.NamedTuple` class or a :class:`typing.TypedDict` class, failing to pass a value to the 'fields' parameter (NT = NamedTuple("NT") or TD = TypedDict("TD")) is deprecated. Passing None to the 'fields' parameter (NT = NamedTuple("NT", None) or TD = TypedDict("TD", None)) is also deprecated. Both will be disallowed in Python 3.15. To create a NamedTuple class with 0 fields, use class NT(NamedTuple): pass or NT = NamedTuple("NT", []). To create a TypedDict class with 0 fields, use class TD(TypedDict): pass or TD = TypedDict("TD", {}). (Contributed by Alex Waygood in :gh:`105566` and :gh:`105570`.)
• :mod:`array`'s 'u' format code, deprecated in docs since Python 3.3, emits :exc:`DeprecationWarning` since 3.13 and will be removed in Python 3.16. Use the 'w' format code instead. (contributed by Hugo van Kemenade in :gh:`80480`)
• :mod:`ctypes`: Deprecate undocumented :func:`!ctypes.SetPointerType` and :func:`!ctypes.ARRAY` functions. Replace ctypes.ARRAY(item_type, size) with item_type * size. (Contributed by Victor Stinner in :gh:`105733`.)

Pending Removal in Python 3.14

• :mod:`argparse`: The type, choices, and metavar parameters of :class:`!argparse.BooleanOptionalAction` are deprecated and will be removed in 3.14. (Contributed by Nikita Sobolev in :gh:`92248`.)

• :mod:`ast`: The following features have been deprecated in documentation since Python 3.8, now cause a :exc:`DeprecationWarning` to be emitted at runtime when they are accessed or used, and will be removed in Python 3.14:

  • :class:`!ast.Num`
  • :class:`!ast.Str`
  • :class:`!ast.Bytes`
  • :class:`!ast.NameConstant`
  • :class:`!ast.Ellipsis`

  Use :class:`ast.Constant` instead. (Contributed by Serhiy Storchaka in :gh:`90953`.)

• :mod:`collections.abc`: Deprecated :class:`~collections.abc.ByteString`. Prefer :class:`!Sequence` or :class:`~collections.abc.Buffer`. For use in typing, prefer a union, like bytes | bytearray, or :class:`collections.abc.Buffer`. (Contributed by Shantanu Jain in :gh:`91896`.)

• :mod:`email`: Deprecated the isdst parameter in :func:`email.utils.localtime`. (Contributed by Alan Williams in :gh:`72346`.)

• :mod:`importlib`: __package__ and __cached__ will cease to be set or taken into consideration by the import system (:gh:`97879`).

• :mod:`importlib.abc` deprecated classes:

  • :class:`!importlib.abc.ResourceReader`
  • :class:`!importlib.abc.Traversable`
  • :class:`!importlib.abc.TraversableResources`

  Use :mod:`importlib.resources.abc` classes instead:

  • :class:`importlib.resources.abc.Traversable`
  • :class:`importlib.resources.abc.TraversableResources`

  (Contributed by Jason R. Coombs and Hugo van Kemenade in :gh:`93963`.)

• :mod:`itertools` had undocumented, inefficient, historically buggy, and inconsistent support for copy, deepcopy, and pickle operations. This will be removed in 3.14 for a significant reduction in code volume and maintenance burden. (Contributed by Raymond Hettinger in :gh:`101588`.)

• :mod:`multiprocessing`: The default start method will change to a safer one on Linux, BSDs, and other non-macOS POSIX platforms where 'fork' is currently the default (:gh:`84559`). Adding a runtime warning about this was deemed too disruptive as the majority of code is not expected to care. Use the :func:`~multiprocessing.get_context` or :func:`~multiprocessing.set_start_method` APIs to explicitly specify when your code requires 'fork'. See :ref:`multiprocessing-start-methods`.

• :mod:`pathlib`: :meth:`~pathlib.PurePath.is_relative_to`, :meth:`~pathlib.PurePath.relative_to`: passing additional arguments is deprecated.

• :func:`pkgutil.find_loader` and :func:`pkgutil.get_loader` now raise :exc:`DeprecationWarning`; use :func:`importlib.util.find_spec` instead. (Contributed by Nikita Sobolev in :gh:`97850`.)

• :mod:`pty`:

  • master_open(): use :func:`pty.openpty`.
  • slave_open(): use :func:`pty.openpty`.

• :func:`shutil.rmtree` onerror parameter is deprecated in 3.12, and will be removed in 3.14: use the onexc parameter instead.

• :mod:`sqlite3`:

  • :data:`~sqlite3.version` and :data:`~sqlite3.version_info`.
  • :meth:`~sqlite3.Cursor.execute` and :meth:`~sqlite3.Cursor.executemany` if :ref:`named placeholders <sqlite3-placeholders>` are used and parameters is a sequence instead of a :class:`dict`.
  • date and datetime adapter, date and timestamp converter: see the :mod:`sqlite3` documentation for suggested replacement recipes.

• :class:`types.CodeType`: Accessing co_lnotab was deprecated in PEP 626 since 3.10 and was planned to be removed in 3.12, but it only got a proper :exc:`DeprecationWarning` in 3.12. May be removed in 3.14. (Contributed by Nikita Sobolev in :gh:`101866`.)

• :mod:`typing`: :class:`~typing.ByteString`, deprecated since Python 3.9, now causes a :exc:`DeprecationWarning` to be emitted when it is used.

• :class:`!urllib.parse.Quoter` is deprecated: it was not intended to be a public API. (Contributed by Gregory P. Smith in :gh:`88168`.)

• :mod:`xml.etree.ElementTree`: Testing the truth value of an :class:`~xml.etree.ElementTree.Element` is deprecated and will raise an exception in Python 3.14.

Pending Removal in Python 3.15

• :class:`typing.NamedTuple`:
  • The undocumented keyword argument syntax for creating NamedTuple classes (NT = NamedTuple("NT", x=int)) is deprecated, and will be disallowed in 3.15. Use the class-based syntax or the functional syntax instead.
  • When using the functional syntax to create a NamedTuple class, failing to pass a value to the 'fields' parameter (NT = NamedTuple("NT")) is deprecated. Passing None to the 'fields' parameter (NT = NamedTuple("NT", None)) is also deprecated. Both will be disallowed in Python 3.15. To create a NamedTuple class with 0 fields, use class NT(NamedTuple): pass or NT = NamedTuple("NT", []).
• :class:`typing.TypedDict`: When using the functional syntax to create a TypedDict class, failing to pass a value to the 'fields' parameter (TD = TypedDict("TD")) is deprecated. Passing None to the 'fields' parameter (TD = TypedDict("TD", None)) is also deprecated. Both will be disallowed in Python 3.15. To create a TypedDict class with 0 fields, use class TD(TypedDict): pass or TD = TypedDict("TD", {}).
• :mod:`wave`: Deprecate the getmark(), setmark() and getmarkers() methods of the :class:`wave.Wave_read` and :class:`wave.Wave_write` classes. They will be removed in Python 3.15. (Contributed by Victor Stinner in :gh:`105096`.)

Pending Removal in Python 3.16

• :class:`array.array` 'u' type (wchar_t): use the 'w' type instead (Py_UCS4).

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.

• :mod:`argparse`: Nesting argument groups and nesting mutually exclusive groups are deprecated.

• :mod:`builtins`:

  • ~bool, bitwise inversion on bool.
  • bool(NotImplemented).
  • Generators: throw(type, exc, tb) and athrow(type, exc, tb) signature is deprecated: use throw(exc) and athrow(exc) instead, the single argument signature.
  • 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 :keyword:`and`, :keyword:`else`, :keyword:`for`, :keyword:`if`, :keyword:`in`, :keyword:`is` and :keyword:`or`. In a future release it will be changed to a syntax error. (:gh:`87999`)
  • Support for __index__() and __int__() method returning non-int type: these methods will be required to return an instance of a strict subclass of :class:`int`.
  • Support for __float__() method returning a strict subclass of :class:`float`: these methods will be required to return an instance of :class:`float`.
  • Support for __complex__() method returning a strict subclass of :class:`complex`: these methods will be required to return an instance of :class:`complex`.
  • Delegation of int() to __trunc__() method.

• :mod:`calendar`: calendar.January and calendar.February constants are deprecated and replaced by :data:`calendar.Month.JANUARY` and :data:`calendar.Month.FEBRUARY`. (Contributed by Prince Roshan in :gh:`103636`.)

• :mod:`datetime`:

  • :meth:`~datetime.datetime.utcnow`: use datetime.datetime.now(tz=datetime.UTC).
  • :meth:`~datetime.datetime.utcfromtimestamp`: use datetime.datetime.fromtimestamp(timestamp, tz=datetime.UTC).

• :mod:`gettext`: Plural value must be an integer.

• :mod:`importlib`:

  • load_module() method: use exec_module() instead.
  • :func:`~importlib.util.cache_from_source` debug_override parameter is deprecated: use the optimization parameter instead.

• :mod:`importlib.metadata`:

  • EntryPoints tuple interface.
  • Implicit None on return values.

• :mod:`importlib.resources`: First parameter to files is renamed to 'anchor'.

• :mod:`importlib.resources` deprecated methods:

  • contents()
  • is_resource()
  • open_binary()
  • open_text()
  • path()
  • read_binary()
  • read_text()

  Use files() instead. Refer to importlib-resources: Migrating from Legacy for migration advice.

• :func:`locale.getdefaultlocale`: use :func:`locale.setlocale()`, :func:`locale.getencoding()` and :func:`locale.getlocale()` instead (:gh:`90817`)

• :mod:`mailbox`: Use of StringIO input and text mode is deprecated, use BytesIO and binary mode instead.

• :mod:`os`: Calling :func:`os.register_at_fork` in multi-threaded process.

• :class:`!pydoc.ErrorDuringImport`: A tuple value for exc_info parameter is deprecated, use an exception instance.

• :mod:`re`: 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`.)

• :mod:`ssl` options and protocols:

  • :class:`ssl.SSLContext` without protocol argument is deprecated.
  • :class:`ssl.SSLContext`: :meth:`~ssl.SSLContext.set_npn_protocols` and :meth:`!~ssl.SSLContext.selected_npn_protocol` are deprecated: use ALPN instead.
  • ssl.OP_NO_SSL* options
  • ssl.OP_NO_TLS* options
  • ssl.PROTOCOL_SSLv3
  • ssl.PROTOCOL_TLS
  • ssl.PROTOCOL_TLSv1
  • ssl.PROTOCOL_TLSv1_1
  • ssl.PROTOCOL_TLSv1_2
  • ssl.TLSVersion.SSLv3
  • ssl.TLSVersion.TLSv1
  • ssl.TLSVersion.TLSv1_1

• :mod:`!sre_compile`, :mod:`!sre_constants` and :mod:`!sre_parse` modules.

• types.CodeType.co_lnotab: use the co_lines attribute instead.

• :class:`typing.Text` (:gh:`92332`).

• :func:`sysconfig.is_python_build` check_home parameter is deprecated and ignored.

• :mod:`threading` methods:

  • :meth:`!threading.Condition.notifyAll`: use :meth:`~threading.Condition.notify_all`.
  • :meth:`!threading.Event.isSet`: use :meth:`~threading.Event.is_set`.
  • :meth:`!threading.Thread.isDaemon`, :meth:`threading.Thread.setDaemon`: use :attr:`threading.Thread.daemon` attribute.
  • :meth:`!threading.Thread.getName`, :meth:`threading.Thread.setName`: use :attr:`threading.Thread.name` attribute.
  • :meth:`!threading.currentThread`: use :meth:`threading.current_thread`.
  • :meth:`!threading.activeCount`: use :meth:`threading.active_count`.

• :class:`unittest.IsolatedAsyncioTestCase`: it is deprecated to return a value that is not None from a test case.

• :mod:`urllib.request`: :class:`~urllib.request.URLopener` and :class:`~urllib.request.FancyURLopener` style of invoking requests is deprecated. Use newer :func:`~urllib.request.urlopen` functions and methods.

• :func:`!urllib.parse.to_bytes`.

• :mod:`urllib.parse` deprecated functions: :func:`~urllib.parse.urlparse` instead

  • splitattr()
  • splithost()
  • splitnport()
  • splitpasswd()
  • splitport()
  • splitquery()
  • splittag()
  • splittype()
  • splituser()
  • splitvalue()

• :mod:`wsgiref`: SimpleHandler.stdout.write() should not do partial writes.

• :meth:`zipimport.zipimporter.load_module` is deprecated: use :meth:`~zipimport.zipimporter.exec_module` instead.

Removed

• PEP 594: Remove the :mod:`!telnetlib` module, deprecated in Python 3.11: use the projects telnetlib3 or Exscript instead. (Contributed by Victor Stinner in :gh:`104773`.)

• Remove the 2to3 program and the :mod:`!lib2to3` module, deprecated in Python 3.11. (Contributed by Victor Stinner in :gh:`104780`.)

• Namespaces typing.io and typing.re, deprecated in Python 3.8, are now removed. The items in those namespaces can be imported directly from :mod:`typing`. (Contributed by Sebastian Rittau in :gh:`92871`.)

• Remove the untested and undocumented :mod:`webbrowser` :class:`!MacOSX` class, deprecated in Python 3.11. Use the :class:`!MacOSXOSAScript` class (introduced in Python 3.2) instead. (Contributed by Hugo van Kemenade in :gh:`104804`.)

• Remove support for using :class:`pathlib.Path` objects as context managers. This functionality was deprecated and made a no-op in Python 3.9.

• Remove the undocumented :class:`!configparser.LegacyInterpolation` class, deprecated in the docstring since Python 3.2, and with a deprecation warning since Python 3.11. (Contributed by Hugo van Kemenade in :gh:`104886`.)

• Remove the :meth:`!turtle.RawTurtle.settiltangle` method, deprecated in docs since Python 3.1 and with a deprecation warning since Python 3.11. (Contributed by Hugo van Kemenade in :gh:`104876`.)

• Removed the following :mod:`unittest` functions, deprecated in Python 3.11:

  • :func:`!unittest.findTestCases`
  • :func:`!unittest.makeSuite`
  • :func:`!unittest.getTestCaseNames`

  Use :class:`~unittest.TestLoader` methods instead:

  • :meth:`unittest.TestLoader.loadTestsFromModule`
  • :meth:`unittest.TestLoader.loadTestsFromTestCase`
  • :meth:`unittest.TestLoader.getTestCaseNames`

  (Contributed by Hugo van Kemenade in :gh:`104835`.)

• PEP 594: Remove the :mod:`!cgi` and :mod:`!cgitb` modules, deprecated in Python 3.11.

  • cgi.FieldStorage can typically be replaced with :func:`urllib.parse.parse_qsl` for GET and HEAD requests, and the :mod:`email.message` module or multipart PyPI project for POST and PUT.

  • cgi.parse() can be replaced by calling :func:`urllib.parse.parse_qs` directly on the desired query string, except for multipart/form-data input, which can be handled as described for cgi.parse_multipart().

  • cgi.parse_multipart() can be replaced with the functionality in the :mod:`email` package (e.g. :class:`email.message.EmailMessage` and :class:`email.message.Message`) which implements the same MIME RFCs, or with the multipart PyPI project.

  • cgi.parse_header() can be replaced with the functionality in the :mod:`email` package, which implements the same MIME RFCs. For example, with :class:`email.message.EmailMessage`:

    from email.message import EmailMessage
    msg = EmailMessage()
    msg['content-type'] = 'application/json; charset="utf8"'
    main, params = msg.get_content_type(), msg['content-type'].params
    

  (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!sndhdr` module, deprecated in Python 3.11: use the projects filetype, puremagic, or python-magic instead. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!pipes` module, deprecated in Python 3.11: use the :mod:`subprocess` module instead. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!ossaudiodev` module, deprecated in Python 3.11: use the pygame project for audio playback. (Contributed by Victor Stinner in :gh:`104780`.)

• PEP 594: Remove the :mod:`!sunau` module, deprecated in Python 3.11. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!mailcap` module, deprecated in Python 3.11. The :mod:`mimetypes` module provides an alternative. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!spwd` module, deprecated in Python 3.11: the python-pam project can be used instead. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!nntplib` module, deprecated in Python 3.11: the PyPI nntplib project can be used instead. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!nis` module, deprecated in Python 3.11. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!xdrlib` module, deprecated in Python 3.11. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!msilib` module, deprecated in Python 3.11. (Contributed by Zachary Ware in :gh:`104773`.)

• PEP 594: Remove the :mod:`!crypt` module and its private :mod:`!_crypt` extension, deprecated in Python 3.11. The :mod:`hashlib` module is a potential replacement for certain use cases. Otherwise, the following PyPI projects can be used:

  • bcrypt: Modern password hashing for your software and your servers.
  • passlib: Comprehensive password hashing framework supporting over 30 schemes.
  • argon2-cffi: The secure Argon2 password hashing algorithm.
  • legacycrypt: Wrapper to the POSIX crypt library call and associated functionality.

  (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!uu` module, deprecated in Python 3.11: the :mod:`base64` module is a modern alternative. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!aifc` module, deprecated in Python 3.11. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!audioop` module, deprecated in Python 3.11. (Contributed by Victor Stinner in :gh:`104773`.)

• PEP 594: Remove the :mod:`!chunk` module, deprecated in Python 3.11. (Contributed by Victor Stinner in :gh:`104773`.)

• Remove support for the keyword-argument method of creating :class:`typing.TypedDict` types, deprecated in Python 3.11. (Contributed by Tomas Roun in :gh:`104786`.)

• PEP 594: Remove the :mod:`!imghdr` module, deprecated in Python 3.11: use the projects filetype, puremagic, or python-magic instead. (Contributed by Victor Stinner in :gh:`104773`.)

• Remove the untested and undocumented :meth:`!unittest.TestProgram.usageExit` method, deprecated in Python 3.11. (Contributed by Hugo van Kemenade in :gh:`104992`.)

• Remove the :mod:`!tkinter.tix` module, deprecated in Python 3.6. The third-party Tix library which the module wrapped is unmaintained. (Contributed by Zachary Ware in :gh:`75552`.)

• Remove the old trashcan macros Py_TRASHCAN_SAFE_BEGIN and Py_TRASHCAN_SAFE_END. They should be replaced by the new macros Py_TRASHCAN_BEGIN and Py_TRASHCAN_END. The new macros were added in Python 3.8 and the old macros were deprecated in Python 3.11. (Contributed by Irit Katriel in :gh:`105111`.)

• Remove locale.resetlocale() function deprecated in Python 3.11: use locale.setlocale(locale.LC_ALL, "") instead. (Contributed by Victor Stinner in :gh:`104783`.)

• :mod:`logging`: Remove undocumented and untested Logger.warn() and LoggerAdapter.warn() methods and logging.warn() function. Deprecated since Python 3.3, they were aliases to the :meth:`logging.Logger.warning` method, :meth:`!logging.LoggerAdapter.warning` method and :func:`logging.warning` function. (Contributed by Victor Stinner in :gh:`105376`.)

• Remove cafile, capath and cadefault parameters of the :func:`urllib.request.urlopen` function, deprecated in Python 3.6: use the context parameter instead. Please use :meth:`ssl.SSLContext.load_cert_chain` instead, or let :func:`ssl.create_default_context` select the system's trusted CA certificates for you. (Contributed by Victor Stinner in :gh:`105382`.)

• Remove deprecated webbrowser.MacOSXOSAScript._name attribute. Use :attr:`webbrowser.MacOSXOSAScript.name <webbrowser.controller.name>` attribute instead. (Contributed by Nikita Sobolev in :gh:`105546`.)

• Remove undocumented, never working, and deprecated re.template function and re.TEMPLATE flag (and re.T alias). (Contributed by Serhiy Storchaka and Nikita Sobolev in :gh:`105687`.)

Porting to Python 3.13

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

• The old trashcan macros Py_TRASHCAN_SAFE_BEGIN and Py_TRASHCAN_SAFE_END were removed. They should be replaced by the new macros Py_TRASHCAN_BEGIN and Py_TRASHCAN_END.

  A tp_dealloc function that has the old macros, such as:

  static void
  mytype_dealloc(mytype *p)
  {
      PyObject_GC_UnTrack(p);
      Py_TRASHCAN_SAFE_BEGIN(p);
      ...
      Py_TRASHCAN_SAFE_END
  }
  

  should migrate to the new macros as follows:

  static void
  mytype_dealloc(mytype *p)
  {
      PyObject_GC_UnTrack(p);
      Py_TRASHCAN_BEGIN(p, mytype_dealloc)
      ...
      Py_TRASHCAN_END
  }
  

  Note that Py_TRASHCAN_BEGIN has a second argument which should be the deallocation function it is in.

Build Changes

• Autoconf 2.71 and aclocal 1.16.4 is now required to regenerate :file:`!configure`. (Contributed by Christian Heimes in :gh:`89886`.)
• SQLite 3.15.2 or newer is required to build the :mod:`sqlite3` extension module. (Contributed by Erlend Aasland in :gh:`105875`.)

C API Changes

New Features

• You no longer have to define the PY_SSIZE_T_CLEAN macro before including :file:`Python.h` when using # formats in :ref:`format codes <arg-parsing-string-and-buffers>`. APIs accepting the format codes always use Py_ssize_t for # formats. (Contributed by Inada Naoki in :gh:`104922`.)
• Add :c:func:`PyImport_AddModuleRef`: similar to :c:func:`PyImport_AddModule`, but return a :term:`strong reference` instead of a :term:`borrowed reference`. (Contributed by Victor Stinner in :gh:`105922`.)
• Add :c:func:`PyWeakref_GetRef` function: similar to :c:func:`PyWeakref_GetObject` but returns a :term:`strong reference`, or NULL if the referent is no longer live. (Contributed by Victor Stinner in :gh:`105927`.)
• Add :c:func:`PyObject_GetOptionalAttr` and :c:func:`PyObject_GetOptionalAttrString`, variants of :c:func:`PyObject_GetAttr` and :c:func:`PyObject_GetAttrString` which don't raise :exc:`AttributeError` if the attribute is not found. These variants are more convenient and faster if the missing attribute should not be treated as a failure. (Contributed by Serhiy Storchaka in :gh:`106521`.)
• Add :c:func:`PyMapping_GetOptionalItem` and :c:func:`PyMapping_GetOptionalItemString`: variants of :c:func:`PyObject_GetItem` and :c:func:`PyMapping_GetItemString` which don't raise :exc:`KeyError` if the key is not found. These variants are more convenient and faster if the missing key should not be treated as a failure. (Contributed by Serhiy Storchaka in :gh:`106307`.)
• If Python is built in :ref:`debug mode <debug-build>` or :option:`with assertions <--with-assertions>`, :c:func:`PyTuple_SET_ITEM` and :c:func:`PyList_SET_ITEM` now check the index argument with an assertion. If the assertion fails, make sure that the size is set before. (Contributed by Victor Stinner in :gh:`106168`.)

Porting to Python 3.13

Deprecated

• Deprecate the old Py_UNICODE and PY_UNICODE_TYPE types: use directly the wchar_t type instead. Since Python 3.3, Py_UNICODE and PY_UNICODE_TYPE are just aliases to wchar_t. (Contributed by Victor Stinner in :gh:`105156`.)

• Deprecate old Python initialization functions:

  • :c:func:`PySys_ResetWarnOptions`: clear :data:`sys.warnoptions` and :data:`!warnings.filters` instead.
  • :c:func:`Py_GetExecPrefix`: get :data:`sys.exec_prefix` instead.
  • :c:func:`Py_GetPath`: get :data:`sys.path` instead.
  • :c:func:`Py_GetPrefix`: get :data:`sys.prefix` instead.
  • :c:func:`Py_GetProgramFullPath`: get :data:`sys.executable` instead.
  • :c:func:`Py_GetProgramName`: get :data:`sys.executable` instead.
  • :c:func:`Py_GetPythonHome`: get :c:member:`PyConfig.home` or :envvar:`PYTHONHOME` environment variable instead.

  Functions scheduled for removal in Python 3.15. (Contributed by Victor Stinner in :gh:`105145`.)

• Deprecate the :c:func:`PyImport_ImportModuleNoBlock` function which is just an alias to :c:func:`PyImport_ImportModule` since Python 3.3. Scheduled for removal in Python 3.15. (Contributed by Victor Stinner in :gh:`105396`.)

• Deprecate the :c:func:`PyWeakref_GetObject` and :c:func:`PyWeakref_GET_OBJECT` functions, which return a :term:`borrowed reference`: use the new :c:func:`PyWeakref_GetRef` function instead, it returns a :term:`strong reference`. The pythoncapi-compat project can be used to get :c:func:`PyWeakref_GetRef` on Python 3.12 and older. (Contributed by Victor Stinner in :gh:`105927`.)

Removed

• Remove functions deprecated in Python 3.9.

  • PyEval_CallObject(), PyEval_CallObjectWithKeywords(): use :c:func:`PyObject_CallNoArgs` or :c:func:`PyObject_Call` instead. Warning: :c:func:`PyObject_Call` positional arguments must be a :class:`tuple` and must not be NULL, keyword arguments must be a :class:`dict` or NULL, whereas removed functions checked arguments type and accepted NULL positional and keyword arguments. To replace PyEval_CallObjectWithKeywords(func, NULL, kwargs) with :c:func:`PyObject_Call`, pass an empty tuple as positional arguments using :c:func:`PyTuple_New(0) <PyTuple_New>`.
  • PyEval_CallFunction(): use :c:func:`PyObject_CallFunction` instead.
  • PyEval_CallMethod(): use :c:func:`PyObject_CallMethod` instead.
  • PyCFunction_Call(): use :c:func:`PyObject_Call` instead.

  (Contributed by Victor Stinner in :gh:`105107`.)

• Remove old buffer protocols deprecated in Python 3.0. Use :ref:`bufferobjects` instead.

  • :c:func:`!PyObject_CheckReadBuffer`: Use :c:func:`PyObject_CheckBuffer` to test if the object supports the buffer protocol. Note that :c:func:`PyObject_CheckBuffer` doesn't guarantee that :c:func:`PyObject_GetBuffer` will succeed. To test if the object is actually readable, see the next example of :c:func:`PyObject_GetBuffer`.

  • :c:func:`!PyObject_AsCharBuffer`, :c:func:`!PyObject_AsReadBuffer`: :c:func:`PyObject_GetBuffer` and :c:func:`PyBuffer_Release` instead:

    Py_buffer view;
    if (PyObject_GetBuffer(obj, &view, PyBUF_SIMPLE) < 0) {
        return NULL;
    }
    // Use `view.buf` and `view.len` to read from the buffer.
    // You may need to cast buf as `(const char*)view.buf`.
    PyBuffer_Release(&view);

  • :c:func:`!PyObject_AsWriteBuffer`: Use :c:func:`PyObject_GetBuffer` and :c:func:`PyBuffer_Release` instead:

    Py_buffer view;
    if (PyObject_GetBuffer(obj, &view, PyBUF_WRITABLE) < 0) {
        return NULL;
    }
    // Use `view.buf` and `view.len` to write to the buffer.
    PyBuffer_Release(&view);

  (Contributed by Inada Naoki in :gh:`85275`.)

• Remove the following old functions to configure the Python initialization, deprecated in Python 3.11:

  • PySys_AddWarnOptionUnicode(): use :c:member:`PyConfig.warnoptions` instead.
  • PySys_AddWarnOption(): use :c:member:`PyConfig.warnoptions` instead.
  • PySys_AddXOption(): use :c:member:`PyConfig.xoptions` instead.
  • PySys_HasWarnOptions(): use :c:member:`PyConfig.xoptions` instead.
  • PySys_SetArgvEx(): set :c:member:`PyConfig.argv` instead.
  • PySys_SetArgv(): set :c:member:`PyConfig.argv` instead.
  • PySys_SetPath(): set :c:member:`PyConfig.module_search_paths` instead.
  • Py_SetPath(): set :c:member:`PyConfig.module_search_paths` instead.
  • Py_SetProgramName(): set :c:member:`PyConfig.program_name` instead.
  • Py_SetPythonHome(): set :c:member:`PyConfig.home` instead.
  • Py_SetStandardStreamEncoding(): set :c:member:`PyConfig.stdio_encoding` instead.
  • _Py_SetProgramFullPath(): set :c:member:`PyConfig.executable` instead.

  Use the new :c:type:`PyConfig` API of the :ref:`Python Initialization Configuration <init-config>` instead (PEP 587), added to Python 3.8. (Contributed by Victor Stinner in :gh:`105145`.)

• Remove PyEval_InitThreads() and PyEval_ThreadsInitialized() functions, deprecated in Python 3.9. Since Python 3.7, Py_Initialize() always creates the GIL: calling PyEval_InitThreads() did nothing and PyEval_ThreadsInitialized() always returned non-zero. (Contributed by Victor Stinner in :gh:`105182`.)

• Remove PyEval_AcquireLock() and PyEval_ReleaseLock() functions, deprecated in Python 3.2. They didn't update the current thread state. They can be replaced with:

  • :c:func:`PyEval_SaveThread` and :c:func:`PyEval_RestoreThread`;
  • low-level :c:func:`PyEval_AcquireThread` and :c:func:`PyEval_RestoreThread`;
  • or :c:func:`PyGILState_Ensure` and :c:func:`PyGILState_Release`.

  (Contributed by Victor Stinner in :gh:`105182`.)

• Remove the old private, undocumented and untested _PyGC_FINALIZED() macro which was kept for backward compatibility with Python 3.8 and older: use :c:func:`PyObject_GC_IsFinalized()` instead. The pythoncapi-compat project can be used to get this function on Python 3.8 and older. (Contributed by Victor Stinner in :gh:`105268`.)

• Remove the old aliases to functions calling functions which were kept for backward compatibility with Python 3.8 provisional API:

  • _PyObject_CallMethodNoArgs(): use PyObject_CallMethodNoArgs()
  • _PyObject_CallMethodOneArg(): use PyObject_CallMethodOneArg()
  • _PyObject_CallOneArg(): use PyObject_CallOneArg()
  • _PyObject_FastCallDict(): use PyObject_VectorcallDict()
  • _PyObject_Vectorcall(): use PyObject_Vectorcall()
  • _PyObject_VectorcallMethod(): use PyObject_VectorcallMethod()
  • _PyVectorcall_Function(): use PyVectorcall_Function()

  Just remove the underscore prefix to update your code. (Contributed by Victor Stinner in :gh:`106084`.)

• Remove private _PyObject_FastCall() function: use PyObject_Vectorcall() which is available since Python 3.8 (PEP 590). (Contributed by Victor Stinner in :gh:`106023`.)

• Remove cpython/pytime.h header file: it only contained private functions. (Contributed by Victor Stinner in :gh:`106316`.)

• Remove _PyInterpreterState_Get() alias to :c:func:`PyInterpreterState_Get()` which was kept for backward compatibility with Python 3.8. The pythoncapi-compat project can be used to get :c:func:`PyInterpreterState_Get()` on Python 3.8 and older. (Contributed by Victor Stinner in :gh:`106320`.)

Pending Removal in Python 3.14

• Creating immutable types (:data:`Py_TPFLAGS_IMMUTABLETYPE`) with mutable bases using the C API.

• Global configuration variables:

  • :c:var:`Py_DebugFlag`: use :c:member:`PyConfig.parser_debug`
  • :c:var:`Py_VerboseFlag`: use :c:member:`PyConfig.verbose`
  • :c:var:`Py_QuietFlag`: use :c:member:`PyConfig.quiet`
  • :c:var:`Py_InteractiveFlag`: use :c:member:`PyConfig.interactive`
  • :c:var:`Py_InspectFlag`: use :c:member:`PyConfig.inspect`
  • :c:var:`Py_OptimizeFlag`: use :c:member:`PyConfig.optimization_level`
  • :c:var:`Py_NoSiteFlag`: use :c:member:`PyConfig.site_import`
  • :c:var:`Py_BytesWarningFlag`: use :c:member:`PyConfig.bytes_warning`
  • :c:var:`Py_FrozenFlag`: use :c:member:`PyConfig.pathconfig_warnings`
  • :c:var:`Py_IgnoreEnvironmentFlag`: use :c:member:`PyConfig.use_environment`
  • :c:var:`Py_DontWriteBytecodeFlag`: use :c:member:`PyConfig.write_bytecode`
  • :c:var:`Py_NoUserSiteDirectory`: use :c:member:`PyConfig.user_site_directory`
  • :c:var:`Py_UnbufferedStdioFlag`: use :c:member:`PyConfig.buffered_stdio`
  • :c:var:`Py_HashRandomizationFlag`: use :c:member:`PyConfig.use_hash_seed` and :c:member:`PyConfig.hash_seed`
  • :c:var:`Py_IsolatedFlag`: use :c:member:`PyConfig.isolated`
  • :c:var:`Py_LegacyWindowsFSEncodingFlag`: use :c:member:`PyPreConfig.legacy_windows_fs_encoding`
  • :c:var:`Py_LegacyWindowsStdioFlag`: use :c:member:`PyConfig.legacy_windows_stdio`
  • :c:var:`!Py_FileSystemDefaultEncoding`: use :c:member:`PyConfig.filesystem_encoding`
  • :c:var:`!Py_HasFileSystemDefaultEncoding`: use :c:member:`PyConfig.filesystem_encoding`
  • :c:var:`!Py_FileSystemDefaultEncodeErrors`: use :c:member:`PyConfig.filesystem_errors`
  • :c:var:`!Py_UTF8Mode`: use :c:member:`PyPreConfig.utf8_mode` (see :c:func:`Py_PreInitialize`)

  The :c:func:`Py_InitializeFromConfig` API should be used with :c:type:`PyConfig` instead.

Pending Removal in Python 3.15

• :c:func:`PyImport_ImportModuleNoBlock`: use :c:func:`PyImport_ImportModule`.
• :c:func:`PyWeakref_GET_OBJECT`: use :c:func:`PyWeakref_GetRef` instead.
• :c:func:`PyWeakref_GetObject`: use :c:func:`PyWeakref_GetRef` instead.
• :c:type:`!Py_UNICODE_WIDE` type: use wchar_t instead.
• :c:type:`Py_UNICODE` type: use wchar_t instead.
• Python initialization functions:
  • :c:func:`PySys_ResetWarnOptions`: clear :data:`sys.warnoptions` and :data:`!warnings.filters` instead.
  • :c:func:`Py_GetExecPrefix`: get :data:`sys.exec_prefix` instead.
  • :c:func:`Py_GetPath`: get :data:`sys.path` instead.
  • :c:func:`Py_GetPrefix`: get :data:`sys.prefix` instead.
  • :c:func:`Py_GetProgramFullPath`: get :data:`sys.executable` instead.
  • :c:func:`Py_GetProgramName`: get :data:`sys.executable` instead.
  • :c:func:`Py_GetPythonHome`: get :c:member:`PyConfig.home` or :envvar:`PYTHONHOME` environment variable instead.

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.

• :const:`Py_TPFLAGS_HAVE_FINALIZE`: no needed since Python 3.8.
• :c:func:`PyErr_Fetch`: use :c:func:`PyErr_GetRaisedException`.
• :c:func:`PyErr_NormalizeException`: use :c:func:`PyErr_GetRaisedException`.
• :c:func:`PyErr_Restore`: use :c:func:`PyErr_SetRaisedException`.
• :c:func:`PyModule_GetFilename`: use :c:func:`PyModule_GetFilenameObject`.
• :c:func:`PyOS_AfterFork`: use :c:func:`PyOS_AfterFork_Child()`.
• :c:func:`PySlice_GetIndicesEx`.
• :c:func:`!PyUnicode_AsDecodedObject`.
• :c:func:`!PyUnicode_AsDecodedUnicode`.
• :c:func:`!PyUnicode_AsEncodedObject`.
• :c:func:`!PyUnicode_AsEncodedUnicode`.
• :c:func:`PyUnicode_READY`: not needed since Python 3.12.
• :c:func:`!_PyErr_ChainExceptions`.
• :c:member:`!PyBytesObject.ob_shash` member: call :c:func:`PyObject_Hash` instead.
• :c:member:`!PyDictObject.ma_version_tag` member.
• TLS API:
  • :c:func:`PyThread_create_key`: use :c:func:`PyThread_tss_alloc`.
  • :c:func:`PyThread_delete_key`: use :c:func:`PyThread_tss_free`.
  • :c:func:`PyThread_set_key_value`: use :c:func:`PyThread_tss_set`.
  • :c:func:`PyThread_get_key_value`: use :c:func:`PyThread_tss_get`.
  • :c:func:`PyThread_delete_key_value`: use :c:func:`PyThread_tss_delete`.
  • :c:func:`PyThread_ReInitTLS`: no longer needed.