3.13.rst

What's New In Python 3.13

Editor:	TBD

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

Important deprecations, removals or restrictions:

• :ref:`PEP 594 <whatsnew313-pep594>`: The remaining 19 "dead batteries" have been removed from the standard library: :mod:`!aifc`, :mod:`!audioop`, :mod:`!cgi`, :mod:`!cgitb`, :mod:`!chunk`, :mod:`!crypt`, :mod:`!imghdr`, :mod:`!mailcap`, :mod:`!msilib`, :mod:`!nis`, :mod:`!nntplib`, :mod:`!ossaudiodev`, :mod:`!pipes`, :mod:`!sndhdr`, :mod:`!spwd`, :mod:`!sunau`, :mod:`!telnetlib`, :mod:`!uu` and :mod:`!xdrlib`.
• PEP 602 ("Annual Release Cycle for Python") has been updated:
  • Python 3.9 - 3.12 have one and a half years of full support, followed by three and a half years of security fixes.
  • Python 3.13 and later have two years of full support, followed by three years of security fixes.

Interpreter improvements:

• PEP 744: A basic :ref:`JIT compiler <whatsnew313-jit-compiler>` was added. It is currently disabled by default (though we may turn it on later). Performance improvements are modest -- we expect to be improving this over the next few releases.

New typing features:

• PEP 742: :data:`typing.TypeIs` was added, providing more intuitive type narrowing behavior.

New Features

Improved Error Messages

• The interpreter now colorizes error messages when displaying tracebacks by default. This feature can be controlled via the new :envvar:`PYTHON_COLORS` environment variable as well as the canonical NO_COLOR and FORCE_COLOR environment variables. See also :ref:`using-on-controlling-color`. (Contributed by Pablo Galindo Salgado in :gh:`112730`.)

• When an incorrect keyword argument is passed to a function, the error message now potentially suggests the correct keyword argument. (Contributed by Pablo Galindo Salgado and Shantanu Jain in :gh:`107944`.)

  >>> "better error messages!".split(max_split=1)
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
      "better error messages!".split(max_split=1)
      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~^^^^^^^^^^^^^
  TypeError: split() got an unexpected keyword argument 'max_split'. Did you mean 'maxsplit'?

• Classes have a new __static_attributes__, populated by the compiler, with a tuple of names of attributes of this class which are accessed through self.X from any function in its body.

Incremental Garbage Collection

• The cycle garbage collector is now incremental. This means that maximum pause times are reduced by an order of magnitude or more for larger heaps.

Other Language Changes

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

• Compiler now strip indents from docstrings. This will reduce the size of :term:`bytecode cache <bytecode>` (e.g. .pyc file). For example, cache file size for sqlalchemy.orm.session in SQLAlchemy 2.0 is reduced by about 5%. This change will affect tools using docstrings, like :mod:`doctest`. (Contributed by Inada Naoki in :gh:`81283`.)

• The :func:`compile` built-in can now accept a new flag, ast.PyCF_OPTIMIZED_AST, which is similar to ast.PyCF_ONLY_AST except that the returned AST is optimized according to the value of the optimize argument. (Contributed by Irit Katriel in :gh:`108113`).

• :mod:`multiprocessing`, :mod:`concurrent.futures`, :mod:`compileall`: Replace :func:`os.cpu_count` with :func:`os.process_cpu_count` to select the default number of worker threads and processes. Get the CPU affinity if supported. (Contributed by Victor Stinner in :gh:`109649`.)

• :func:`os.path.realpath` now resolves MS-DOS style file names even if the file is not accessible. (Contributed by Moonsik Park in :gh:`82367`.)

• Fixed a bug where a :keyword:`global` declaration in an :keyword:`except` block is rejected when the global is used in the :keyword:`else` block. (Contributed by Irit Katriel in :gh:`111123`.)

• Many functions now emit a warning if a boolean value is passed as a file descriptor argument. This can help catch some errors earlier. (Contributed by Serhiy Storchaka in :gh:`82626`.)

• Added a new environment variable :envvar:`PYTHON_FROZEN_MODULES`. It determines whether or not frozen modules are ignored by the import machinery, equivalent of the :option:`-X frozen_modules <-X>` command-line option. (Contributed by Yilei Yang in :gh:`111374`.)

• The new :envvar:`PYTHON_HISTORY` environment variable can be used to change the location of a .python_history file. (Contributed by Levi Sabah, Zackery Spytz and Hugo van Kemenade in :gh:`73965`.)

• Add :exc:`PythonFinalizationError` exception. This exception derived from :exc:`RuntimeError` is raised when an operation is blocked during the :term:`Python finalization <interpreter shutdown>`.

  The following functions now raise PythonFinalizationError, instead of :exc:`RuntimeError`:

  • :func:`_thread.start_new_thread`.
  • :class:`subprocess.Popen`.
  • :func:`os.fork`.
  • :func:`os.forkpty`.

  (Contributed by Victor Stinner in :gh:`114570`.)

• Allow controlling Expat >=2.6.0 reparse deferral (:cve:`2023-52425`) by adding five new methods:

  • :meth:`xml.etree.ElementTree.XMLParser.flush`
  • :meth:`xml.etree.ElementTree.XMLPullParser.flush`
  • :meth:`xml.parsers.expat.xmlparser.GetReparseDeferralEnabled`
  • :meth:`xml.parsers.expat.xmlparser.SetReparseDeferralEnabled`
  • :meth:`!xml.sax.expatreader.ExpatParser.flush`

  (Contributed by Sebastian Pipping in :gh:`115623`.)

• The :func:`ssl.create_default_context` API now includes :data:`ssl.VERIFY_X509_PARTIAL_CHAIN` and :data:`ssl.VERIFY_X509_STRICT` in its default flags.

  Note

  :data:`ssl.VERIFY_X509_STRICT` may reject pre-RFC 5280 or malformed certificates that the underlying OpenSSL implementation otherwise would accept. While disabling this is not recommended, you can do so using:

  ctx = ssl.create_default_context()
  ctx.verify_flags &= ~ssl.VERIFY_X509_STRICT
  

  (Contributed by William Woodruff in :gh:`112389`.)

• The :class:`configparser.ConfigParser` now accepts unnamed sections before named ones if configured to do so. (Contributed by Pedro Sousa Lacerda in :gh:`66449`.)

New Modules

• None yet.

Improved Modules

argparse

• Add parameter deprecated in methods :meth:`~argparse.ArgumentParser.add_argument` and :meth:`!add_parser` which allows to deprecate command-line options, positional arguments and subcommands. (Contributed by Serhiy Storchaka in :gh:`83648`.)

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`.)
• Add clear() method in order to implement MutableSequence. (Contributed by Mike Zimin in :gh:`114894`.)

ast

• The constructors of node types in the :mod:`ast` module are now stricter in the arguments they accept, and have more intuitive behaviour when arguments are omitted.

  If an optional field on an AST node is not included as an argument when constructing an instance, the field will now be set to None. Similarly, if a list field is omitted, that field will now be set to an empty list. (Previously, in both cases, the attribute would be missing on the newly constructed AST node instance.)

  If other arguments are omitted, a :exc:`DeprecationWarning` is emitted. This will cause an exception in Python 3.15. Similarly, passing a keyword argument that does not map to a field on the AST node is now deprecated, and will raise an exception in Python 3.15.

• :func:`ast.parse` now accepts an optional argument optimize which is passed on to the :func:`compile` built-in. This makes it possible to obtain an optimized AST. (Contributed by Irit Katriel in :gh:`108113`.)

asyncio

• :meth:`asyncio.loop.create_unix_server` will now automatically remove the Unix socket when the server is closed. (Contributed by Pierre Ossman in :gh:`111246`.)

• :meth:`asyncio.DatagramTransport.sendto` will now send zero-length datagrams if called with an empty bytes object. The transport flow control also now accounts for the datagram header when calculating the buffer size. (Contributed by Jamie Phan in :gh:`115199`.)

• Add :meth:`asyncio.Server.close_clients` and :meth:`asyncio.Server.abort_clients` methods which allow to more forcefully close an asyncio server. (Contributed by Pierre Ossman in :gh:`113538`.)

• :func:`asyncio.as_completed` now returns an object that is both an :term:`asynchronous iterator` and a plain :term:`iterator` of awaitables. The awaitables yielded by asynchronous iteration include original task or future objects that were passed in, making it easier to associate results with the tasks being completed. (Contributed by Justin Arthur in :gh:`77714`.)

• When :func:`asyncio.TaskGroup.create_task` is called on an inactive :class:`asyncio.TaskGroup`, the given coroutine will be closed (which prevents a :exc:`RuntimeWarning` about the given coroutine being never awaited). (Contributed by Arthur Tacca and Jason Zhang in :gh:`115957`.)

• Improved behavior of :class:`asyncio.TaskGroup` when an external cancellation collides with an internal cancellation. For example, when two task groups are nested and both experience an exception in a child task simultaneously, it was possible that the outer task group would hang, because its internal cancellation was swallowed by the inner task group.

  In the case where a task group is cancelled externally and also must raise an :exc:`ExceptionGroup`, it will now call the parent task's :meth:`~asyncio.Task.cancel` method. This ensures that a :exc:`asyncio.CancelledError` will be raised at the next :keyword:`await`, so the cancellation is not lost.

  An added benefit of these changes is that task groups now preserve the cancellation count (:meth:`asyncio.Task.cancelling`).

  In order to handle some corner cases, :meth:`asyncio.Task.uncancel` may now reset the undocumented _must_cancel flag when the cancellation count reaches zero.

  (Inspired by an issue reported by Arthur Tacca in :gh:`116720`.)

• Add :meth:`asyncio.Queue.shutdown` (along with :exc:`asyncio.QueueShutDown`) for queue termination. (Contributed by Laurie Opperman and Yves Duprat in :gh:`104228`.)

• Accept a tuple of separators in :meth:`asyncio.StreamReader.readuntil`, stopping when one of them is encountered. (Contributed by Bruce Merry in :gh:`81322`.)

base64

• Add :func:`base64.z85encode` and :func:`base64.z85decode` functions which allow encoding and decoding Z85 data. See Z85 specification for more information. (Contributed by Matan Perelman in :gh:`75299`.)

copy

• Add :func:`copy.replace` function which allows to create a modified copy of an object, which is especially useful for immutable objects. It supports named tuples created with the factory function :func:`collections.namedtuple`, :class:`~dataclasses.dataclass` instances, various :mod:`datetime` objects, :class:`~inspect.Signature` objects, :class:`~inspect.Parameter` objects, :ref:`code object <code-objects>`, and any user classes which define the :meth:`!__replace__` method. (Contributed by Serhiy Storchaka in :gh:`108751`.)

dbm

• Add :meth:`dbm.gnu.gdbm.clear` and :meth:`dbm.ndbm.ndbm.clear` methods that remove all items from the database. (Contributed by Donghee Na in :gh:`107122`.)
• Add new :mod:`dbm.sqlite3` backend, and make it the default :mod:`!dbm` backend. (Contributed by Raymond Hettinger and Erlend E. Aasland in :gh:`100414`.)

dis

• Change the output of :mod:`dis` module functions to show logical labels for jump targets and exception handlers, rather than offsets. The offsets can be added with the new -O command line option or the show_offsets parameter. (Contributed by Irit Katriel in :gh:`112137`.)

doctest

• The :meth:`doctest.DocTestRunner.run` method now counts the number of skipped tests. Add :attr:`doctest.DocTestRunner.skips` and :attr:`doctest.TestResults.skipped` attributes. (Contributed by Victor Stinner in :gh:`108794`.)

email

• :func:`email.utils.getaddresses` and :func:`email.utils.parseaddr` now return ('', '') 2-tuples in more situations where invalid email addresses are encountered instead of potentially inaccurate values. Add optional strict parameter to these two functions: use strict=False to get the old behavior, accept malformed inputs. getattr(email.utils, 'supports_strict_parsing', False) can be used to check if the strict parameter is available. (Contributed by Thomas Dwyer and Victor Stinner for :gh:`102988` to improve the :cve:`2023-27043` fix.)

fractions

• Formatting for objects of type :class:`fractions.Fraction` now supports the standard format specification mini-language rules for fill, alignment, sign handling, minimum width and grouping. (Contributed by Mark Dickinson in :gh:`111320`.)

gc

• The cyclic garbage collector is now incremental, which changes the meanings of the results of :meth:`gc.get_threshold` and :meth:`gc.set_threshold` as well as :meth:`gc.get_count` and :meth:`gc.get_stats`.

  • :meth:`gc.get_threshold` returns a three-item tuple for backwards compatibility. The first value is the threshold for young collections, as before; the second value determines the rate at which the old collection is scanned (the default is 10, and higher values mean that the old collection is scanned more slowly). The third value is meaningless and is always zero.
  • :meth:`gc.set_threshold` ignores any items after the second.
  • :meth:`gc.get_count` and :meth:`gc.get_stats` return the same format of results as before. The only difference is that instead of the results referring to the young, aging and old generations, the results refer to the young generation and the aging and collecting spaces of the old generation.

  In summary, code that attempted to manipulate the behavior of the cycle GC may not work exactly as intended, but it is very unlikely to be harmful. All other code will work just fine.

glob

• Add :func:`glob.translate` function that converts a path specification with shell-style wildcards to a regular expression. (Contributed by Barney Gale in :gh:`72904`.)

importlib

• Previously deprecated :mod:`importlib.resources` functions are un-deprecated:

  • :func:`~importlib.resources.is_resource()`
  • :func:`~importlib.resources.open_binary()`
  • :func:`~importlib.resources.open_text()`
  • :func:`~importlib.resources.path()`
  • :func:`~importlib.resources.read_binary()`
  • :func:`~importlib.resources.read_text()`

  All now allow for a directory (or tree) of resources, using multiple positional arguments.

  For text-reading functions, the encoding and errors must now be given as keyword arguments.

  The :func:`~importlib.resources.contents()` remains deprecated in favor of the full-featured :class:`~importlib.resources.abc.Traversable` API. However, there is now no plan to remove it.

  (Contributed by Petr Viktorin in :gh:`106532`.)

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`.)

ipaddress

• Add the :attr:`ipaddress.IPv4Address.ipv6_mapped` property, which returns the IPv4-mapped IPv6 address. (Contributed by Charles Machalow in :gh:`109466`.)
• Fix is_global and is_private behavior in :class:`~ipaddress.IPv4Address`, :class:`~ipaddress.IPv6Address`, :class:`~ipaddress.IPv4Network` and :class:`~ipaddress.IPv6Network`.

itertools

• Added a strict option to :func:`itertools.batched`. This raises a :exc:`ValueError` if the final batch is shorter than the specified batch size. (Contributed by Raymond Hettinger in :gh:`113202`.)

marshal

• Add the allow_code parameter in module functions. Passing allow_code=False prevents serialization and de-serialization of code objects which are incompatible between Python versions. (Contributed by Serhiy Storchaka in :gh:`113626`.)

math

• A new function :func:`~math.fma` for fused multiply-add operations has been added. This function computes x * y + z with only a single round, and so avoids any intermediate loss of precision. It wraps the fma() function provided by C99, and follows the specification of the IEEE 754 "fusedMultiplyAdd" operation for special cases. (Contributed by Mark Dickinson and Victor Stinner in :gh:`73468`.)

mmap

• The :class:`mmap.mmap` class now has an :meth:`~mmap.mmap.seekable` method that can be used when a seekable file-like object is required. The :meth:`~mmap.mmap.seek` method now returns the new absolute position. (Contributed by Donghee Na and Sylvie Liberman in :gh:`111835`.)
• :class:`mmap.mmap` now has a trackfd parameter on Unix; if it is False, the file descriptor specified by fileno will not be duplicated. (Contributed by Zackery Spytz and Petr Viktorin in :gh:`78502`.)

opcode

• Move opcode.ENABLE_SPECIALIZATION to _opcode.ENABLE_SPECIALIZATION. This field was added in 3.12, it was never documented and is not intended for external usage. (Contributed by Irit Katriel in :gh:`105481`.)
• Removed opcode.is_pseudo, opcode.MIN_PSEUDO_OPCODE and opcode.MAX_PSEUDO_OPCODE, which were added in 3.12, were never documented or exposed through dis, and were not intended to be used externally.

os

• Add :func:`os.process_cpu_count` function to get the number of logical CPUs usable by the calling thread of the current process. (Contributed by Victor Stinner in :gh:`109649`.)
• Add a low level interface for Linux's timer notification file descriptors via :func:`os.timerfd_create`, :func:`os.timerfd_settime`, :func:`os.timerfd_settime_ns`, :func:`os.timerfd_gettime`, and :func:`os.timerfd_gettime_ns`, :const:`os.TFD_NONBLOCK`, :const:`os.TFD_CLOEXEC`, :const:`os.TFD_TIMER_ABSTIME`, and :const:`os.TFD_TIMER_CANCEL_ON_SET` (Contributed by Masaru Tsuchiyama in :gh:`108277`.)
• :func:`os.cpu_count` and :func:`os.process_cpu_count` can be overridden through the new environment variable :envvar:`PYTHON_CPU_COUNT` or the new command-line option :option:`-X cpu_count <-X>`. This option is useful for users who need to limit CPU resources of a container system without having to modify the container (application code). (Contributed by Donghee Na in :gh:`109595`.)
• Add support of :func:`os.lchmod` and the follow_symlinks argument in :func:`os.chmod` on Windows. Note that the default value of follow_symlinks in :func:`!os.lchmod` is False on Windows. (Contributed by Serhiy Storchaka in :gh:`59616`.)
• Add support of :func:`os.fchmod` and a file descriptor in :func:`os.chmod` on Windows. (Contributed by Serhiy Storchaka in :gh:`113191`.)
• :func:`os.posix_spawn` now accepts env=None, which makes the newly spawned process use the current process environment. (Contributed by Jakub Kulik in :gh:`113119`.)
• :func:`os.posix_spawn` gains an :attr:`os.POSIX_SPAWN_CLOSEFROM` attribute for use in file_actions= on platforms that support :c:func:`!posix_spawn_file_actions_addclosefrom_np`. (Contributed by Jakub Kulik in :gh:`113117`.)

os.path

• Add :func:`os.path.isreserved` to check if a path is reserved on the current system. This function is only available on Windows. (Contributed by Barney Gale in :gh:`88569`.)
• On Windows, :func:`os.path.isabs` no longer considers paths starting with exactly one (back)slash to be absolute. (Contributed by Barney Gale and Jon Foster in :gh:`44626`.)

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 :meth:`pathlib.Path.from_uri`, a new constructor to create a :class:`pathlib.Path` object from a 'file' URI (file://). (Contributed by Barney Gale in :gh:`107465`.)
• Add :meth:`pathlib.PurePath.full_match` for matching paths with shell-style wildcards, including the recursive wildcard "**". (Contributed by Barney Gale in :gh:`73435`.)
• Add :attr:`pathlib.PurePath.parser` class attribute that stores the implementation of :mod:`os.path` used for low-level path parsing and joining: either posixpath or ntpath.
• Add recurse_symlinks keyword-only argument to :meth:`pathlib.Path.glob` and :meth:`~pathlib.Path.rglob`. (Contributed by Barney Gale in :gh:`77609`.)
• Add follow_symlinks keyword-only argument to :meth:`~pathlib.Path.is_file`, :meth:`~pathlib.Path.is_dir`, :meth:`~pathlib.Path.owner`, :meth:`~pathlib.Path.group`. (Contributed by Barney Gale in :gh:`105793`, and Kamil Turek in :gh:`107962`.)
• Return files and directories from :meth:`pathlib.Path.glob` and :meth:`~pathlib.Path.rglob` when given a pattern that ends with "**". In earlier versions, only directories were returned. (Contributed by Barney Gale in :gh:`70303`.)

pdb

• Add ability to move between chained exceptions during post mortem debugging in :func:`~pdb.pm` using the new exceptions [exc_number] command for Pdb. (Contributed by Matthias Bussonnier in :gh:`106676`.)
• Expressions/statements whose prefix is a pdb command are now correctly identified and executed. (Contributed by Tian Gao in :gh:`108464`.)
• sys.path[0] will no longer be replaced by the directory of the script being debugged when sys.flags.safe_path is set (via the :option:`-P` command line option or :envvar:`PYTHONSAFEPATH` environment variable). (Contributed by Tian Gao and Christian Walther in :gh:`111762`.)

queue

• Add :meth:`queue.Queue.shutdown` (along with :exc:`queue.ShutDown`) for queue termination. (Contributed by Laurie Opperman and Yves Duprat in :gh:`104750`.)

re

• Rename :exc:`!re.error` to :exc:`re.PatternError` for improved clarity. :exc:`!re.error` is kept for backward compatibility.

sqlite3

• A :exc:`ResourceWarning` is now emitted if a :class:`sqlite3.Connection` object is not :meth:`closed <sqlite3.Connection.close>` explicitly. (Contributed by Erlend E. Aasland in :gh:`105539`.)
• Add filter keyword-only parameter to :meth:`sqlite3.Connection.iterdump` for filtering database objects to dump. (Contributed by Mariusz Felisiak in :gh:`91602`.)

statistics

• Add :func:`statistics.kde` for kernel density estimation. This makes it possible to estimate a continuous probability density function from a fixed number of discrete samples. (Contributed by Raymond Hettinger in :gh:`115863`.)

subprocess

• The :mod:`subprocess` module now uses the :func:`os.posix_spawn` function in more situations. Notably in the default case of close_fds=True on more recent versions of platforms including Linux, FreeBSD, and Solaris where the C library provides :c:func:`!posix_spawn_file_actions_addclosefrom_np`. On Linux this should perform similar to our existing Linux :c:func:`!vfork` based code. A private control knob :attr:`!subprocess._USE_POSIX_SPAWN` can be set to False if you need to force :mod:`subprocess` not to ever use :func:`os.posix_spawn`. Please report your reason and platform details in the CPython issue tracker if you set this so that we can improve our API selection logic for everyone. (Contributed by Jakub Kulik in :gh:`113117`.)

sys

• Add the :func:`sys._is_interned` function to test if the string was interned. This function is not guaranteed to exist in all implementations of Python. (Contributed by Serhiy Storchaka in :gh:`78573`.)

time

• On Windows, :func:`time.monotonic()` now uses the QueryPerformanceCounter() clock to have a resolution better than 1 us, instead of the GetTickCount64() clock which has a resolution of 15.6 ms. (Contributed by Victor Stinner in :gh:`88494`.)
• On Windows, :func:`time.time()` now uses the GetSystemTimePreciseAsFileTime() clock to have a resolution better than 1 μs, instead of the GetSystemTimeAsFileTime() clock which has a resolution of 15.6 ms. (Contributed by Victor Stinner in :gh:`63207`.)

tkinter

• Add :mod:`tkinter` widget methods: :meth:`!tk_busy_hold`, :meth:`!tk_busy_configure`, :meth:`!tk_busy_cget`, :meth:`!tk_busy_forget`, :meth:`!tk_busy_current`, and :meth:`!tk_busy_status`. (Contributed by Miguel, klappnase and Serhiy Storchaka in :gh:`72684`.)
• The :mod:`tkinter` widget method :meth:`!wm_attributes` now accepts the attribute name without the minus prefix to get window attributes, e.g. w.wm_attributes('alpha') and allows to specify attributes and values to set as keyword arguments, e.g. w.wm_attributes(alpha=0.5). Add new optional keyword-only parameter return_python_dict: calling w.wm_attributes(return_python_dict=True) returns the attributes as a dict instead of a tuple. (Contributed by Serhiy Storchaka in :gh:`43457`.)
• Add new optional keyword-only parameter return_ints in the :meth:`!Text.count` method. Passing return_ints=True makes it always returning the single count as an integer instead of a 1-tuple or None. (Contributed by Serhiy Storchaka in :gh:`97928`.)
• Add support of the "vsapi" element type in the :meth:`~tkinter.ttk.Style.element_create` method of :class:`tkinter.ttk.Style`. (Contributed by Serhiy Storchaka in :gh:`68166`.)

traceback

• Add show_group parameter 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`.)
• Add the field exc_type_str to :class:`~traceback.TracebackException`, which holds a string display of the exc_type. Deprecate the field exc_type which holds the type object itself. Add parameter save_exc_type (default True) to indicate whether exc_type should be saved. (Contributed by Irit Katriel in :gh:`112332`.)

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`.)
• Add :data:`typing.ReadOnly`, a special typing construct to mark an item of a :class:`typing.TypedDict` as read-only for type checkers. See PEP 705 for more details.

unicodedata

• The Unicode database has been updated to version 15.1.0. (Contributed by James Gerity in :gh:`109559`.)

venv

• Add support for adding source control management (SCM) ignore files to a virtual environment's directory. By default, Git is supported. This is implemented as opt-in via the API which can be extended to support other SCMs (:class:`venv.EnvBuilder` and :func:`venv.create`), and opt-out via the CLI (using --without-scm-ignore-files). (Contributed by Brett Cannon in :gh:`108125`.)

warnings

• The new :func:`warnings.deprecated` decorator provides a way to communicate deprecations to :term:`static type checkers <static type checker>` and to warn on usage of deprecated classes and functions. A runtime deprecation warning may also be emitted when a decorated function or class is used at runtime. See PEP 702. (Contributed by Jelle Zijlstra in :gh:`104003`.)

xml.etree.ElementTree

• Add the :meth:`!close` method for the iterator returned by :func:`~xml.etree.ElementTree.iterparse` for explicit cleaning up. (Contributed by Serhiy Storchaka in :gh:`69893`.)

zipimport

• Gains support for ZIP64 format files. Everybody loves huge code right? (Contributed by Tim Hatch in :gh:`94146`.)

Optimizations

• :func:`textwrap.indent` is now ~30% faster than before for large input. (Contributed by Inada Naoki in :gh:`107369`.)
• The :mod:`subprocess` module uses :func:`os.posix_spawn` in more situations including the default where close_fds=True on many modern platforms. This should provide a noteworthy performance increase launching processes on FreeBSD and Solaris. See the :ref:`subprocess <whatsnew313-subprocess>` section above for details. (Contributed by Jakub Kulik in :gh:`113117`.)

Experimental JIT Compiler

When CPython is configured using the --enable-experimental-jit option, a just-in-time compiler is added which can speed up some Python programs.

The internal architecture is roughly as follows.

• We start with specialized Tier 1 bytecode. See :ref:`What's new in 3.11 <whatsnew311-pep659>` for details.
• When the Tier 1 bytecode gets hot enough, it gets translated to a new, purely internal Tier 2 IR, a.k.a. micro-ops ("uops").
• The Tier 2 IR uses the same stack-based VM as Tier 1, but the instruction format is better suited to translation to machine code.
• We have several optimization passes for Tier 2 IR, which are applied before it is interpreted or translated to machine code.
• There is a Tier 2 interpreter, but it is mostly intended for debugging the earlier stages of the optimization pipeline. If the JIT is not enabled, the Tier 2 interpreter can be invoked by passing Python the -X uops option or by setting the PYTHON_UOPS environment variable to 1.
• When the --enable-experimental-jit option is used, the optimized Tier 2 IR is translated to machine code, which is then executed. This does not require additional runtime options.
• The machine code translation process uses an architecture called copy-and-patch. It has no runtime dependencies, but there is a new build-time dependency on LLVM.

See PEP 744 for more details.

(JIT by Brandt Bucher, inspired by a paper by Haoran Xu and Fredrik Kjolstad. Tier 2 IR by Mark Shannon and Guido van Rossum. Tier 2 optimizer by Ken Jin.)

Deprecated

• :mod:`array`: :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`.)

• :mod:`decimal`: Deprecate non-standard format specifier "N" for :class:`decimal.Decimal`. It was not documented and only supported in the C implementation. (Contributed by Serhiy Storchaka in :gh:`89902`.)

• :mod:`dis`: The dis.HAVE_ARGUMENT separator is deprecated. Check membership in :data:`~dis.hasarg` instead. (Contributed by Irit Katriel in :gh:`109319`.)

• :ref:`frame-objects`: Calling :meth:`frame.clear` on a suspended frame raises :exc:`RuntimeError` (as has always been the case for an executing frame). (Contributed by Irit Katriel in :gh:`79932`.)

• :mod:`getopt` and :mod:`optparse` modules: They are now :term:`soft deprecated`: the :mod:`argparse` module should be used for new projects. Previously, the :mod:`optparse` module was already deprecated, its removal was not scheduled, and no warnings was emitted: so there is no change in practice. (Contributed by Victor Stinner in :gh:`106535`.)

• :mod:`gettext`: Emit deprecation warning for non-integer numbers in :mod:`gettext` functions and methods that consider plural forms even if the translation was not found. (Contributed by Serhiy Storchaka in :gh:`88434`.)

• :mod:`glob`: The undocumented :func:`!glob.glob0` and :func:`!glob.glob1` functions are deprecated. Use :func:`glob.glob` and pass a directory to its root_dir argument instead. (Contributed by Barney Gale in :gh:`117337`.)

• :mod:`http.server`: :class:`http.server.CGIHTTPRequestHandler` now emits a :exc:`DeprecationWarning` as it will be removed in 3.15. Process-based CGI HTTP servers have been out of favor for a very long time. This code was outdated, unmaintained, and rarely used. It has a high potential for both security and functionality bugs. This includes removal of the --cgi flag to the python -m http.server command line in 3.15.

• :mod:`pathlib`: :meth:`pathlib.PurePath.is_reserved` is deprecated and scheduled for removal in Python 3.15. Use :func:`os.path.isreserved` to detect reserved paths on Windows.

• :mod:`platform`: :func:`~platform.java_ver` is deprecated and will be removed in 3.15. It was largely untested, had a confusing API, and was only useful for Jython support. (Contributed by Nikita Sobolev in :gh:`116349`.)

• :mod:`pydoc`: Deprecate undocumented :func:`!pydoc.ispackage` function. (Contributed by Zackery Spytz in :gh:`64020`.)

• :mod:`sqlite3`: Passing more than one positional argument to :func:`sqlite3.connect` and the :class:`sqlite3.Connection` constructor is deprecated. The remaining parameters will become keyword-only in Python 3.15.

  Deprecate passing name, number of arguments, and the callable as keyword arguments for the following :class:`sqlite3.Connection` APIs:

  • :meth:`~sqlite3.Connection.create_function`
  • :meth:`~sqlite3.Connection.create_aggregate`

  Deprecate passing the callback callable by keyword for the following :class:`sqlite3.Connection` APIs:

  • :meth:`~sqlite3.Connection.set_authorizer`
  • :meth:`~sqlite3.Connection.set_progress_handler`
  • :meth:`~sqlite3.Connection.set_trace_callback`

  The affected parameters will become positional-only in Python 3.15.

  (Contributed by Erlend E. Aasland in :gh:`107948` and :gh:`108278`.)

• :mod:`sys`: :func:`sys._enablelegacywindowsfsencoding` function. Replace it with the :envvar:`PYTHONLEGACYWINDOWSFSENCODING` environment variable. (Contributed by Inada Naoki in :gh:`73427`.)

• :mod:`tarfile`: The undocumented and unused tarfile attribute of :class:`tarfile.TarFile` is deprecated and scheduled for removal in Python 3.16.

• :mod:`traceback`: The field exc_type of :class:`traceback.TracebackException` is deprecated. Use exc_type_str instead.

• :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`.)
  • 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`.)
  • :func:`typing.no_type_check_decorator` is deprecated, and scheduled for removal in Python 3.15. After eight years in the :mod:`typing` module, it has yet to be supported by any major type checkers. (Contributed by Alex Waygood in :gh:`106309`.)
  • :data:`typing.AnyStr` is deprecated. In Python 3.16, it will be removed from typing.__all__, and a :exc:`DeprecationWarning` will be emitted when it is imported or accessed. It will be removed entirely in Python 3.18. Use the new :ref:`type parameter syntax <type-params>` instead. (Contributed by Michael The in :gh:`107116`.)

• :ref:`user-defined-funcs`: Assignment to a function's :attr:`~function.__code__` attribute where the new code object's type does not match the function's type, is deprecated. The different types are: plain function, generator, async generator and coroutine. (Contributed by Irit Katriel in :gh:`81137`.)

• :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 3.14

• :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` and :meth:`~pathlib.PurePath.relative_to`: passing additional arguments is deprecated.

• :mod:`pkgutil`: :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 :attr:`~codeobject.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.

• :mod:`urllib`: :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:`http.server.CGIHTTPRequestHandler` will be removed along with its related --cgi flag to python -m http.server. It was obsolete and rarely used. No direct replacement exists. Anything is better than CGI to interface a web server with a request handler.
• :class:`locale`: :func:`locale.getdefaultlocale` was deprecated in Python 3.11 and originally planned for removal in Python 3.13 (:gh:`90817`), but removal has been postponed to Python 3.15. Use :func:`locale.setlocale()`, :func:`locale.getencoding()` and :func:`locale.getlocale()` instead. (Contributed by Hugo van Kemenade in :gh:`111187`.)
• :mod:`pathlib`: :meth:`pathlib.PurePath.is_reserved` is deprecated and scheduled for removal in Python 3.15. Use :func:`os.path.isreserved` to detect reserved paths on Windows.
• :mod:`platform`: :func:`~platform.java_ver` is deprecated and will be removed in 3.15. It was largely untested, had a confusing API, and was only useful for Jython support. (Contributed by Nikita Sobolev in :gh:`116349`.)
• :mod:`threading`: Passing any arguments to :func:`threading.RLock` is now deprecated. C version allows any numbers of args and kwargs, but they are just ignored. Python version does not allow any arguments. All arguments will be removed from :func:`threading.RLock` in Python 3.15. (Contributed by Nikita Sobolev in :gh:`102029`.)
• :class:`typing.NamedTuple`:
  • The undocumented keyword argument syntax for creating :class:`!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 :class:`!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 :class:`!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 :class:`!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 :class:`!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 (:c: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.JANUARY` and :data:`calendar.FEBRUARY`. (Contributed by Prince Roshan in :gh:`103636`.)
• :attr:`codeobject.co_lnotab`: use the :meth:`codeobject.co_lines` method instead.
• :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:`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:`!sre_compile`, :mod:`!sre_constants` and :mod:`!sre_parse` modules.
• :mod:`ssl` options and protocols:
  • :class:`ssl.SSLContext` without protocol argument is deprecated.
  • :class:`ssl.SSLContext`: :meth:`~ssl.SSLContext.set_npn_protocols` and :meth:`!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
• :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:`typing.Text` (:gh:`92332`).
• :class:`unittest.IsolatedAsyncioTestCase`: it is deprecated to return a value that is not None from a test case.
• :mod:`urllib.parse` deprecated functions: :func:`~urllib.parse.urlparse` instead
  • splitattr()
  • splithost()
  • splitnport()
  • splitpasswd()
  • splitport()
  • splitquery()
  • splittag()
  • splittype()
  • splituser()
  • splitvalue()
  • to_bytes()
• :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.
• :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: dead batteries

• PEP 594 removed 19 modules from the standard library, deprecated in Python 3.11:

  • :mod:`!aifc`. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!audioop`. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!chunk`. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!cgi` and :mod:`!cgitb`.

    • cgi.FieldStorage can typically be replaced with :func:`urllib.parse.parse_qsl` for GET and HEAD requests, and the :mod:`email.message` module or :pypi:`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_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
      

    • 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 :pypi:`multipart` PyPI project.

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

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

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

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

  • :mod:`!imghdr`: use the projects :pypi:`filetype`, :pypi:`puremagic`, or :pypi:`python-magic` instead. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!mailcap`. The :mod:`mimetypes` module provides an alternative. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!msilib`. (Contributed by Zachary Ware in :gh:`104773`.)

  • :mod:`!nis`. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!nntplib`: the :pypi:`nntplib` PyPI project can be used instead. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!ossaudiodev`: use the pygame project for audio playback. (Contributed by Victor Stinner in :gh:`104780`.)

  • :mod:`!pipes`: use the :mod:`subprocess` module instead. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!sndhdr`: use the projects :pypi:`filetype_, :pypi:`puremagic`, or :pypi:`python-magic` instead. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!spwd`: the :pypi:`python-pam` project can be used instead. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!sunau`. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!telnetlib`, use the projects :pypi:`telnetlib3 ` or :pypi:`Exscript` instead. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!uu`: the :mod:`base64` module is a modern alternative. (Contributed by Victor Stinner in :gh:`104773`.)

  • :mod:`!xdrlib`. (Contributed by Victor Stinner in :gh:`104773`.)

2to3

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

configparser

• 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`.)

importlib

• Remove deprecated :meth:`~object.__getitem__` access for :class:`!importlib.metadata.EntryPoint` objects. (Contributed by Jason R. Coombs in :gh:`113175`.)

locale

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

logging

• :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`.)

pathlib

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

re

• 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`.)

tkinter

• 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`.)

turtle

• 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`.)

typing

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

unittest

• 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`.)

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

urllib

• 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`.)

webbrowser

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

Others

• None yet

CPython bytecode changes

• The oparg of YIELD_VALUE is now 1 if the yield is part of a yield-from or await, and 0 otherwise. The oparg of RESUME was changed to add a bit indicating whether the except-depth is 1, which is needed to optimize closing of generators. (Contributed by Irit Katriel in :gh:`111354`.)

Porting to Python 3.13

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

Changes in the Python API

• Functions :c:func:`PyDict_GetItem`, :c:func:`PyDict_GetItemString`, :c:func:`PyMapping_HasKey`, :c:func:`PyMapping_HasKeyString`, :c:func:`PyObject_HasAttr`, :c:func:`PyObject_HasAttrString`, and :c:func:`PySys_GetObject`, which clear all errors which occurred when calling them, now report them using :func:`sys.unraisablehook`. You may replace them with other functions as recommended in the documentation. (Contributed by Serhiy Storchaka in :gh:`106672`.)

• An :exc:`OSError` is now raised by :func:`getpass.getuser` for any failure to retrieve a username, instead of :exc:`ImportError` on non-Unix platforms or :exc:`KeyError` on Unix platforms where the password database is empty.

• The :mod:`threading` module now expects the :mod:`!_thread` module to have an _is_main_interpreter attribute. It is a function with no arguments that return True if the current interpreter is the main interpreter.

  Any library or application that provides a custom _thread module must provide _is_main_interpreter(), just like the module's other "private" attributes. (See :gh:`112826`.)

• :class:`mailbox.Maildir` now ignores files with a leading dot. (Contributed by Zackery Spytz in :gh:`65559`.)

• :meth:`pathlib.Path.glob` and :meth:`~pathlib.Path.rglob` now return both files and directories if a pattern that ends with "**" is given, rather than directories only. Users may add a trailing slash to match only directories.

• :c:func:`!PyCode_GetFirstFree` is an unstable API now and has been renamed to :c:func:`PyUnstable_Code_GetFirstFree`. (Contributed by Bogdan Romanyuk in :gh:`115781`.)

Build Changes

• Autoconf 2.71 and aclocal 1.16.4 are now required to regenerate the :file:`configure` script. (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`.)
• Python built with :file:`configure` :option:`--with-trace-refs` (tracing references) is now ABI compatible with the Python release build and :ref:`debug build <debug-build>`. (Contributed by Victor Stinner in :gh:`108634`.)
• Building CPython now requires a compiler with support for the C11 atomic library, GCC built-in atomic functions, or MSVC interlocked intrinsics.
• The errno, fcntl, grp, md5, pwd, resource, termios, winsound, _ctypes_test, _multiprocessing.posixshmem, _scproxy, _stat, _statistics, _testconsole, _testimportmultiple and _uuid C extensions are now built with the :ref:`limited C API <limited-c-api>`. (Contributed by Victor Stinner in :gh:`85283`.)
• wasm32-wasi is now a PEP 11 tier 2 platform. (Contributed by Brett Cannon in :gh:`115192`.)
• wasm32-emscripten is no longer a PEP 11 supported platform. (Contributed by Brett Cannon in :gh:`115192`.)

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`.)

• The keywords parameter of :c:func:`PyArg_ParseTupleAndKeywords` and :c:func:`PyArg_VaParseTupleAndKeywords` now has type :c:expr:`char * const *` in C and :c:expr:`const char * const *` in C++, instead of :c:expr:`char **`. It makes these functions compatible with arguments of type :c:expr:`const char * const *`, :c:expr:`const char **` or :c:expr:`char * const *` in C++ and :c:expr:`char * const *` in C without an explicit type cast. This can be overridden with the :c:macro:`PY_CXX_CONST` macro. (Contributed by Serhiy Storchaka in :gh:`65210`.)

• 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`.)

• Add fixed variants of functions which silently ignore errors:

  • :c:func:`PyObject_HasAttrWithError` replaces :c:func:`PyObject_HasAttr`.
  • :c:func:`PyObject_HasAttrStringWithError` replaces :c:func:`PyObject_HasAttrString`.
  • :c:func:`PyMapping_HasKeyWithError` replaces :c:func:`PyMapping_HasKey`.
  • :c:func:`PyMapping_HasKeyStringWithError` replaces :c:func:`PyMapping_HasKeyString`.

  New functions return not only 1 for true and 0 for false, but also -1 for error.

  (Contributed by Serhiy Storchaka in :gh:`108511`.)

• 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. (Contributed by Victor Stinner in :gh:`106168`.)

• Add :c:func:`PyModule_Add` function: similar to :c:func:`PyModule_AddObjectRef` and :c:func:`PyModule_AddObject` but always steals a reference to the value. (Contributed by Serhiy Storchaka in :gh:`86493`.)

• Add :c:func:`PyDict_GetItemRef` and :c:func:`PyDict_GetItemStringRef` functions: similar to :c:func:`PyDict_GetItemWithError` but returning a :term:`strong reference` instead of a :term:`borrowed reference`. Moreover, these functions return -1 on error and so checking PyErr_Occurred() is not needed. (Contributed by Victor Stinner in :gh:`106004`.)

• Added :c:func:`PyDict_SetDefaultRef`, which is similar to :c:func:`PyDict_SetDefault` but returns a :term:`strong reference` instead of a :term:`borrowed reference`. This function returns -1 on error, 0 on insertion, and 1 if the key was already present in the dictionary. (Contributed by Sam Gross in :gh:`112066`.)

• Add :c:func:`PyDict_ContainsString` function: same as :c:func:`PyDict_Contains`, but key is specified as a :c:expr:`const char*` UTF-8 encoded bytes string, rather than a :c:expr:`PyObject*`. (Contributed by Victor Stinner in :gh:`108314`.)

• Added :c:func:`PyList_GetItemRef` function: similar to :c:func:`PyList_GetItem` but returns a :term:`strong reference` instead of a :term:`borrowed reference`.

• Add :c:func:`Py_IsFinalizing` function: check if the main Python interpreter is :term:`shutting down <interpreter shutdown>`. (Contributed by Victor Stinner in :gh:`108014`.)

• Add :c:func:`PyLong_AsInt` function: similar to :c:func:`PyLong_AsLong`, but store the result in a C :c:expr:`int` instead of a C :c:expr:`long`. Previously, it was known as the private function :c:func:`!_PyLong_AsInt` (with an underscore prefix). (Contributed by Victor Stinner in :gh:`108014`.)

• Python built with :file:`configure` :option:`--with-trace-refs` (tracing references) now supports the :ref:`Limited API <limited-c-api>`. (Contributed by Victor Stinner in :gh:`108634`.)

• Add :c:func:`PyObject_VisitManagedDict` and :c:func:`PyObject_ClearManagedDict` functions which must be called by the traverse and clear functions of a type using :c:macro:`Py_TPFLAGS_MANAGED_DICT` flag. The pythoncapi-compat project can be used to get these functions on Python 3.11 and 3.12. (Contributed by Victor Stinner in :gh:`107073`.)

• Add :c:func:`PyUnicode_EqualToUTF8AndSize` and :c:func:`PyUnicode_EqualToUTF8` functions: compare Unicode object with a :c:expr:`const char*` UTF-8 encoded string and return true (1) if they are equal, or false (0) otherwise. These functions do not raise exceptions. (Contributed by Serhiy Storchaka in :gh:`110289`.)

• Add :c:func:`PyThreadState_GetUnchecked()` function: similar to :c:func:`PyThreadState_Get()`, but don't kill the process with a fatal error if it is NULL. The caller is responsible to check if the result is NULL. Previously, the function was private and known as _PyThreadState_UncheckedGet(). (Contributed by Victor Stinner in :gh:`108867`.)

• Add :c:func:`PySys_AuditTuple` function: similar to :c:func:`PySys_Audit`, but pass event arguments as a Python :class:`tuple` object. (Contributed by Victor Stinner in :gh:`85283`.)

• :c:func:`PyArg_ParseTupleAndKeywords` now supports non-ASCII keyword parameter names. (Contributed by Serhiy Storchaka in :gh:`110815`.)

• Add :c:func:`PyMem_RawMalloc`, :c:func:`PyMem_RawCalloc`, :c:func:`PyMem_RawRealloc` and :c:func:`PyMem_RawFree` to the limited C API (version 3.13). (Contributed by Victor Stinner in :gh:`85283`.)

• Add :c:func:`PySys_Audit` and :c:func:`PySys_AuditTuple` functions to the limited C API. (Contributed by Victor Stinner in :gh:`85283`.)

• Add :c:func:`PyErr_FormatUnraisable` function: similar to :c:func:`PyErr_WriteUnraisable`, but allow customizing the warning message. (Contributed by Serhiy Storchaka in :gh:`108082`.)

• Add :c:func:`PyList_Extend` and :c:func:`PyList_Clear` functions: similar to Python list.extend() and list.clear() methods. (Contributed by Victor Stinner in :gh:`111138`.)

• Add :c:func:`PyDict_Pop` and :c:func:`PyDict_PopString` functions: remove a key from a dictionary and optionally return the removed value. This is similar to :meth:`dict.pop`, but without the default value and not raising :exc:`KeyError` if the key is missing. (Contributed by Stefan Behnel and Victor Stinner in :gh:`111262`.)

• Add :c:func:`Py_HashPointer` function to hash a pointer. (Contributed by Victor Stinner in :gh:`111545`.)

• Add :c:func:`PyObject_GenericHash` function that implements the default hashing function of a Python object. (Contributed by Serhiy Storchaka in :gh:`113024`.)

• Add PyTime C API:

  • :c:type:`PyTime_t` type.
  • :c:var:`PyTime_MIN` and :c:var:`PyTime_MAX` constants.
  • :c:func:`PyTime_AsSecondsDouble` :c:func:`PyTime_Monotonic`, :c:func:`PyTime_PerfCounter`, and :c:func:`PyTime_Time` functions.

  (Contributed by Victor Stinner and Petr Viktorin in :gh:`110850`.)

• Add :c:func:`PyLong_AsNativeBytes`, :c:func:`PyLong_FromNativeBytes` and :c:func:`PyLong_FromUnsignedNativeBytes` functions to simplify converting between native integer types and Python :class:`int` objects. (Contributed by Steve Dower in :gh:`111140`.)

• Add :c:func:`PyType_GetFullyQualifiedName` function to get the type's fully qualified name. Equivalent to f"{type.__module__}.{type.__qualname__}", or type.__qualname__ if type.__module__ is not a string or is equal to "builtins". (Contributed by Victor Stinner in :gh:`111696`.)

• Add :c:func:`PyType_GetModuleName` function to get the type's module name. Equivalent to getting the type.__module__ attribute. (Contributed by Eric Snow and Victor Stinner in :gh:`111696`.)

• Add support for %T, %#T, %N and %#N formats to :c:func:`PyUnicode_FromFormat`: format the fully qualified name of an object type and of a type: call :c:func:`PyType_GetModuleName`. See PEP 737 for more information. (Contributed by Victor Stinner in :gh:`111696`.)

• Add :c:func:`Py_GetConstant` and :c:func:`Py_GetConstantBorrowed` functions to get constants. For example, Py_GetConstant(Py_CONSTANT_ZERO) returns a :term:`strong reference` to the constant zero. (Contributed by Victor Stinner in :gh:`115754`.)

• Add :c:func:`PyType_GetModuleByDef` to the limited C API (Contributed by Victor Stinner in :gh:`116936`.)

Porting to Python 3.13

• Python.h no longer includes the <ieeefp.h> standard header. It was included for the finite() function which is now provided by the <math.h> header. It should now be included explicitly if needed. Remove also the HAVE_IEEEFP_H macro. (Contributed by Victor Stinner in :gh:`108765`.)

• Python.h no longer includes these standard header files: <time.h>, <sys/select.h> and <sys/time.h>. If needed, they should now be included explicitly. For example, <time.h> provides the clock() and gmtime() functions, <sys/select.h> provides the select() function, and <sys/time.h> provides the futimes(), gettimeofday() and setitimer() functions. (Contributed by Victor Stinner in :gh:`108765`.)

• On Windows, Python.h no longer includes the <stddef.h> standard header file. If needed, it should now be included explicitly. For example, it provides offsetof() function, and size_t and ptrdiff_t types. Including <stddef.h> explicitly was already needed by all other platforms, the HAVE_STDDEF_H macro is only defined on Windows. (Contributed by Victor Stinner in :gh:`108765`.)

• If the :c:macro:`Py_LIMITED_API` macro is defined, :c:macro:`!Py_BUILD_CORE`, :c:macro:`!Py_BUILD_CORE_BUILTIN` and :c:macro:`!Py_BUILD_CORE_MODULE` macros are now undefined by <Python.h>. (Contributed by Victor Stinner in :gh:`85283`.)

• 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.

Deprecated

• Passing optional arguments maxsplit, count and flags in module-level functions :func:`re.split`, :func:`re.sub` and :func:`re.subn` as positional arguments is now deprecated. In future Python versions these parameters will be :ref:`keyword-only <keyword-only_parameter>`. (Contributed by Serhiy Storchaka in :gh:`56166`.)

• Deprecate the old Py_UNICODE and PY_UNICODE_TYPE types: use directly the :c:type:`wchar_t` type instead. Since Python 3.3, Py_UNICODE and PY_UNICODE_TYPE are just aliases to :c:type:`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

• Removed chained :class:`classmethod` descriptors (introduced in :gh:`63272`). This can no longer be used to wrap other descriptors such as :class:`property`. The core design of this feature was flawed and caused a number of downstream problems. To "pass-through" a :class:`classmethod`, consider using the :attr:`!__wrapped__` attribute that was added in Python 3.10. (Contributed by Raymond Hettinger in :gh:`89519`.)

• Remove many APIs (functions, macros, variables) with names prefixed by _Py or _PY (considered as private API). If your project is affected by one of these removals and you consider that the removed API should remain available, please open a new issue to request a public C API and add cc @vstinner to the issue to notify Victor Stinner. (Contributed by Victor Stinner in :gh:`106320`.)

• 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, and set also maybe :c:member:`PyConfig.legacy_windows_stdio` (on Windows).
  • _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 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 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 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`.)

• The :c:func:`PyModule_AddObject` function is now :term:`soft deprecated`: :c:func:`PyModule_Add` or :c:func:`PyModule_AddObjectRef` functions should be used instead. (Contributed by Serhiy Storchaka in :gh:`86493`.)

Pending Removal in Python 3.14

• Creating immutable types (:c:macro:`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 :c:type:`wchar_t` instead.
• :c:type:`Py_UNICODE` type: use :c:type:`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.

• :c:macro:`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.
• Remove undocumented PY_TIMEOUT_MAX constant from the limited C API. (Contributed by Victor Stinner in :gh:`110014`.)

Regression Test Changes

• Python built with :file:`configure` :option:`--with-pydebug` now supports a :option:`-X presite=package.module <-X>` command-line option. If used, it specifies a module that should be imported early in the lifecycle of the interpreter, before site.py is executed. (Contributed by Łukasz Langa in :gh:`110769`.)