3.14.rst

What's New In Python 3.14

Editor:	TBD

This article explains the new features in Python 3.14, compared to 3.13.

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

Summary -- Release highlights

New Features

Improved Error Messages

• When unpacking assignment fails due to incorrect number of variables, the error message prints the received number of values in more cases than before. (Contributed by Tushar Sadhwani in :gh:`122239`.)

  >>> x, y, z = 1, 2, 3, 4
  Traceback (most recent call last):
    File "<stdin>", line 1, in <module>
      x, y, z = 1, 2, 3, 4
      ^^^^^^^
  ValueError: too many values to unpack (expected 3, got 4)

Other Language Changes

• Incorrect usage of :keyword:`await` and asynchronous comprehensions is now detected even if the code is optimized away by the :option:`-O` command line option. For example, python -O -c 'assert await 1' now produces a :exc:`SyntaxError`. (Contributed by Jelle Zijlstra in :gh:`121637`.)
• Writes to __debug__ are now detected even if the code is optimized away by the :option:`-O` command line option. For example, python -O -c 'assert (__debug__ := 1)' now produces a :exc:`SyntaxError`. (Contributed by Irit Katriel in :gh:`122245`.)
• Added class methods :meth:`float.from_number` and :meth:`complex.from_number` to convert a number to :class:`float` or :class:`complex` type correspondingly. They raise an error if the argument is a string. (Contributed by Serhiy Storchaka in :gh:`84978`.)

New Modules

• None yet.

Improved Modules

ast

• Added :func:`ast.compare` for comparing two ASTs. (Contributed by Batuhan Taskaya and Jeremy Hylton in :issue:`15987`.)
• Add support for :func:`copy.replace` for AST nodes. (Contributed by Bénédikt Tran in :gh:`121141`.)
• Docstrings are now removed from an optimized AST in optimization level 2. (Contributed by Irit Katriel in :gh:`123958`.)

ctypes

• The layout of :ref:`bit fields <ctypes-bit-fields-in-structures-unions>` in :class:`~ctypes.Structure` and :class:`~ctypes.Union` now matches platform defaults (GCC/Clang or MVSC) more closely. In particular, fields no longer overlap. (Contributed by Matthias Görgens in :gh:`97702`.)
• The :attr:`.Structure._layout_` class attribute can now be set to help match a non-default ABI. (Contributed by Petr Viktorin in :gh:`97702`.)

dis

• Added support for rendering full source location information of :class:`instructions <dis.Instruction>`, rather than only the line number. This feature is added to the following interfaces via the show_positions keyword argument:

  • :class:`dis.Bytecode`,
  • :func:`dis.dis`, :func:`dis.distb`, and
  • :func:`dis.disassemble`.

  This feature is also exposed via :option:`dis --show-positions`.

  (Contributed by Bénédikt Tran in :gh:`123165`.)

fractions

Added support for converting any objects that have the :meth:`!as_integer_ratio` method to a :class:`~fractions.Fraction`. (Contributed by Serhiy Storchaka in :gh:`82017`.)

functools

• :func:`functools.update_wrapper` and :func:`functools.wraps` now have special support for wrapping :term:`annotate functions <annotate function>`. A new parameter delegated was added to both. (Contributed by Jelle Zijlstra in :gh:`124342`.)

http

Directory lists and error pages generated by the :mod:`http.server` module allow the browser to apply its default dark mode. (Contributed by Yorik Hansen in :gh:`123430`.)

json

Add notes for JSON serialization errors that allow to identify the source of the error. (Contributed by Serhiy Storchaka in :gh:`122163`.)

Enable :mod:`json` module to work as a script using the :option:`-m` switch: python -m json. See the :ref:`JSON command-line interface <json-commandline>` documentation. (Contributed by Trey Hunner in :gh:`122873`.)

operator

• Two new functions operator.is_none and operator.is_not_none have been added, such that operator.is_none(obj) is equivalent to obj is None and operator.is_not_none(obj) is equivalent to obj is not None. (Contributed by Raymond Hettinger and Nico Mexis in :gh:`115808`.)

os

• Added the :data:`os.environ.refresh() <os.environ>` method to update :data:`os.environ` with changes to the environment made by :func:`os.putenv`, by :func:`os.unsetenv`, or made outside Python in the same process. (Contributed by Victor Stinner in :gh:`120057`.)

pathlib

• Add methods to :class:`pathlib.Path` to recursively copy or move files and directories:

  • :meth:`~pathlib.Path.copy` copies a file or directory tree to a destination.
  • :meth:`~pathlib.Path.copy_into` copies into a destination directory.
  • :meth:`~pathlib.Path.move` moves a file or directory tree to a destination.
  • :meth:`~pathlib.Path.move_into` moves into a destination directory.

  (Contributed by Barney Gale in :gh:`73991`.)

pdb

• Hard-coded breakpoints (:func:`breakpoint` and :func:`pdb.set_trace`) now reuse the most recent :class:`~pdb.Pdb` instance that calls :meth:`~pdb.Pdb.set_trace`, instead of creating a new one each time. As a result, all the instance specific data like :pdbcmd:`display` and :pdbcmd:`commands` are preserved across hard-coded breakpoints. (Contributed by Tian Gao in :gh:`121450`.)

pickle

• Set the default protocol version on the :mod:`pickle` module to 5. For more details, please see :ref:`pickle protocols <pickle-protocols>`.
• Add notes for pickle serialization errors that allow to identify the source of the error. (Contributed by Serhiy Storchaka in :gh:`122213`.)

symtable

• Expose the following :class:`symtable.Symbol` methods:

  • :meth:`~symtable.Symbol.is_free_class`
  • :meth:`~symtable.Symbol.is_comp_iter`
  • :meth:`~symtable.Symbol.is_comp_cell`

  (Contributed by Bénédikt Tran in :gh:`120029`.)

unicodedata

• The Unicode database has been updated to Unicode 16.0.0.

Optimizations

asyncio

• :mod:`asyncio` now uses double linked list implementation for native tasks which speeds up execution by 10% on standard pyperformance benchmarks and reduces memory usage. (Contributed by Kumar Aditya in :gh:`107803`.)

Deprecated

• :mod:`builtins`: Passing a complex number as the real or imag argument in the :func:`complex` constructor is now deprecated; it should only be passed as a single positional argument. (Contributed by Serhiy Storchaka in :gh:`109218`.)
• :mod:`os`: :term:`Soft deprecate <soft deprecated>` :func:`os.popen` and :func:`os.spawn* <os.spawnl>` functions. They should no longer be used to write new code. The :mod:`subprocess` module is recommended instead. (Contributed by Victor Stinner in :gh:`120743`.)
• :mod:`symtable`: Deprecate :meth:`symtable.Class.get_methods` due to the lack of interest. (Contributed by Bénédikt Tran in :gh:`119698`.)

Removed

argparse

• Remove the type, choices, and metavar parameters of :class:`!argparse.BooleanOptionalAction`. They were deprecated since 3.12.

ast

• Remove the following classes. They were all deprecated since Python 3.8, and have emitted deprecation warnings since Python 3.12:

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

  Use :class:`ast.Constant` instead. As a consequence of these removals, user-defined visit_Num, visit_Str, visit_Bytes, visit_NameConstant and visit_Ellipsis methods on custom :class:`ast.NodeVisitor` subclasses will no longer be called when the NodeVisitor subclass is visiting an AST. Define a visit_Constant method instead.

  Also, remove the following deprecated properties on :class:`ast.Constant`, which were present for compatibility with the now-removed AST classes:

  • :attr:`!ast.Constant.n`
  • :attr:`!ast.Constant.s`

  Use :attr:`!ast.Constant.value` instead.

  (Contributed by Alex Waygood in :gh:`119562`.)

asyncio

• Remove the following classes and functions. They were all deprecated and emitted deprecation warnings since Python 3.12:

  • :class:`!asyncio.AbstractChildWatcher`
  • :class:`!asyncio.SafeChildWatcher`
  • :class:`!asyncio.MultiLoopChildWatcher`
  • :class:`!asyncio.FastChildWatcher`
  • :class:`!asyncio.ThreadedChildWatcher`
  • :class:`!asyncio.PidfdChildWatcher`
  • :meth:`!asyncio.AbstractEventLoopPolicy.get_child_watcher`
  • :meth:`!asyncio.AbstractEventLoopPolicy.set_child_watcher`
  • :func:`!asyncio.get_child_watcher`
  • :func:`!asyncio.set_child_watcher`

  (Contributed by Kumar Aditya in :gh:`120804`.)

collections.abc

• Remove :class:`!collections.abc.ByteString`. It had previously raised a :exc:`DeprecationWarning` since Python 3.12.

email

• Remove the isdst parameter from :func:`email.utils.localtime`. (Contributed by Hugo van Kemenade in :gh:`118798`.)

importlib

• Remove deprecated :mod:`importlib.abc` 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`.)

itertools

• Remove :mod:`itertools` support for copy, deepcopy, and pickle operations. These had previously raised a :exc:`DeprecationWarning` since Python 3.12. (Contributed by Raymond Hettinger in :gh:`101588`.)

pathlib

• Remove support for passing additional keyword arguments to :class:`pathlib.Path`. In previous versions, any such arguments are ignored.
• Remove support for passing additional positional arguments to :meth:`pathlib.PurePath.relative_to` and :meth:`~pathlib.PurePath.is_relative_to`. In previous versions, any such arguments are joined onto other.

pty

• Remove deprecated :func:`!pty.master_open` and :func:`!pty.slave_open`. They had previously raised a :exc:`DeprecationWarning` since Python 3.12. Use :func:`pty.openpty` instead. (Contributed by Nikita Sobolev in :gh:`118824`.)

sqlite3

• Remove :data:`!version` and :data:`!version_info` from :mod:`sqlite3`. (Contributed by Hugo van Kemenade in :gh:`118924`.)
• Disallow using a sequence of parameters with named placeholders. This had previously raised a :exc:`DeprecationWarning` since Python 3.12; it will now raise a :exc:`sqlite3.ProgrammingError`. (Contributed by Erlend E. Aasland in :gh:`118928` and :gh:`101693`.)

typing

• Remove :class:`!typing.ByteString`. It had previously raised a :exc:`DeprecationWarning` since Python 3.12.

urllib

• Remove deprecated :class:`!Quoter` class from :mod:`urllib.parse`. It had previously raised a :exc:`DeprecationWarning` since Python 3.11. (Contributed by Nikita Sobolev in :gh:`118827`.)

Others

• Using :data:`NotImplemented` in a boolean context will now raise a :exc:`TypeError`. It had previously raised a :exc:`DeprecationWarning` since Python 3.9. (Contributed by Jelle Zijlstra in :gh:`118767`.)
• The :func:`int` built-in no longer delegates to :meth:`~object.__trunc__`. Classes that want to support conversion to integer must implement either :meth:`~object.__int__` or :meth:`~object.__index__`. (Contributed by Mark Dickinson in :gh:`119743`.)

Porting to Python 3.14

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

Changes in the Python API

• :class:`functools.partial` is now a method descriptor. Wrap it in :func:`staticmethod` if you want to preserve the old behavior. (Contributed by Serhiy Storchaka and Dominykas Grigonis in :gh:`121027`.)

Build Changes

C API Changes

New Features

• Add :c:func:`PyLong_GetSign` function to get the sign of :class:`int` objects. (Contributed by Sergey B Kirpichev in :gh:`116560`.)

• Add a new :c:type:`PyUnicodeWriter` API to create a Python :class:`str` object:

  • :c:func:`PyUnicodeWriter_Create`.
  • :c:func:`PyUnicodeWriter_Discard`.
  • :c:func:`PyUnicodeWriter_Finish`.
  • :c:func:`PyUnicodeWriter_WriteChar`.
  • :c:func:`PyUnicodeWriter_WriteUTF8`.
  • :c:func:`PyUnicodeWriter_WriteUCS4`.
  • :c:func:`PyUnicodeWriter_WriteWideChar`.
  • :c:func:`PyUnicodeWriter_WriteStr`.
  • :c:func:`PyUnicodeWriter_WriteRepr`.
  • :c:func:`PyUnicodeWriter_WriteSubstring`.
  • :c:func:`PyUnicodeWriter_Format`.
  • :c:func:`PyUnicodeWriter_DecodeUTF8Stateful`.

  (Contributed by Victor Stinner in :gh:`119182`.)

• Add :c:func:`PyIter_NextItem` to replace :c:func:`PyIter_Next`, which has an ambiguous return value. (Contributed by Irit Katriel and Erlend Aasland in :gh:`105201`.)

• :c:func:`Py_Finalize` now deletes all interned strings. This is backwards incompatible to any C-Extension that holds onto an interned string after a call to :c:func:`Py_Finalize` and is then reused after a call to :c:func:`Py_Initialize`. Any issues arising from this behavior will normally result in crashes during the exectuion of the subsequent call to :c:func:`Py_Initialize` from accessing uninitialized memory. To fix, use an address sanitizer to identify any use-after-free coming from an interned string and deallocate it during module shutdown. (Contribued by Eddie Elizondo in :gh:`113601`.)

• Add new functions to convert C <stdint.h> numbers from/to Python :class:`int`:

  • :c:func:`PyLong_FromInt32`
  • :c:func:`PyLong_FromInt64`
  • :c:func:`PyLong_FromUInt32`
  • :c:func:`PyLong_FromUInt64`
  • :c:func:`PyLong_AsInt32`
  • :c:func:`PyLong_AsInt64`
  • :c:func:`PyLong_AsUInt32`
  • :c:func:`PyLong_AsUInt64`

  (Contributed by Victor Stinner in :gh:`120389`.)

• Add :c:func:`PyBytes_Join(sep, iterable) <PyBytes_Join>` function, similar to sep.join(iterable) in Python. (Contributed by Victor Stinner in :gh:`121645`.)

• Add :c:func:`Py_HashBuffer` to compute and return the hash value of a buffer. (Contributed by Antoine Pitrou and Victor Stinner in :gh:`122854`.)

• Add functions to get and set the current runtime Python configuration (PEP 741):

  • :c:func:`PyConfig_Get`
  • :c:func:`PyConfig_GetInt`
  • :c:func:`PyConfig_Set`
  • :c:func:`PyConfig_Names`

  (Contributed by Victor Stinner in :gh:`107954`.)

• Add functions to configure the Python initialization (PEP 741):

  • :c:func:`PyInitConfig_Create`
  • :c:func:`PyInitConfig_Free`
  • :c:func:`PyInitConfig_GetError`
  • :c:func:`PyInitConfig_GetExitCode`
  • :c:func:`PyInitConfig_HasOption`
  • :c:func:`PyInitConfig_GetInt`
  • :c:func:`PyInitConfig_GetStr`
  • :c:func:`PyInitConfig_GetStrList`
  • :c:func:`PyInitConfig_FreeStrList`
  • :c:func:`PyInitConfig_SetInt`
  • :c:func:`PyInitConfig_SetStr`
  • :c:func:`PyInitConfig_SetStrList`
  • :c:func:`PyInitConfig_AddModule`
  • :c:func:`Py_InitializeFromInitConfig`

  (Contributed by Victor Stinner in :gh:`107954`.)

• Add :c:func:`PyType_GetBaseByToken` and :c:data:`Py_tp_token` slot for easier superclass identification, which attempts to resolve the type checking issue mentioned in PEP 630 (:gh:`124153`).

Porting to Python 3.14

• In the limited C API 3.14 and newer, :c:func:`Py_TYPE` is now implemented as an opaque function call to hide implementation details. (Contributed by Victor Stinner in :gh:`120600`.)

Deprecated

• Macros :c:macro:`!Py_IS_NAN`, :c:macro:`!Py_IS_INFINITY` and :c:macro:`!Py_IS_FINITE` are :term:`soft deprecated`, use instead :c:macro:`!isnan`, :c:macro:`!isinf` and :c:macro:`!isfinite` available from :file:`math.h` since C99. (Contributed by Sergey B Kirpichev in :gh:`119613`.)
• :func:`!asyncio.iscoroutinefunction` is deprecated and will be removed in Python 3.16, use :func:`inspect.iscoroutinefunction` instead. (Contributed by Jiahao Li and Kumar Aditya in :gh:`122875`.)

Removed

• Creating :c:data:`immutable types <Py_TPFLAGS_IMMUTABLETYPE>` with mutable bases was deprecated since 3.12 and now raises a :exc:`TypeError`.