**************************** What's New In Python 3.14 **************************** :Editor: TBD .. Rules for maintenance: * Anyone can add text to this document. Do not spend very much time on the wording of your changes, because your text will probably get rewritten to some degree. * The maintainer will go through Misc/NEWS periodically and add changes; it's therefore more important to add your changes to Misc/NEWS than to this file. * This is not a complete list of every single change; completeness is the purpose of Misc/NEWS. Some changes I consider too small or esoteric to include. If such a change is added to the text, I'll just remove it. (This is another reason you shouldn't spend too much time on writing your addition.) * If you want to draw your new text to the attention of the maintainer, add 'XXX' to the beginning of the paragraph or section. * It's OK to just add a fragmentary note about a change. For example: "XXX Describe the transmogrify() function added to the socket module." The maintainer will research the change and write the necessary text. * You can comment out your additions if you like, but it's not necessary (especially when a final release is some months away). * Credit the author of a patch or bugfix. Just the name is sufficient; the e-mail address isn't necessary. * It's helpful to add the issue number as a comment: XXX Describe the transmogrify() function added to the socket module. (Contributed by P.Y. Developer in :gh:`12345`.) This saves the maintainer the effort of going through the VCS log when researching a change. This article explains the new features in Python 3.14, compared to 3.13. For full details, see the :ref:`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 ============================= .. This section singles out the most important changes in Python 3.14. Brevity is key. .. PEP-sized items next. New Features ============ Other Language Changes ====================== 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`.) os -- * Added the :data:`os.environ.refresh() ` 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 :meth:`pathlib.Path.copy`, which copies the content of one file to another, like :func:`shutil.copyfile`. (Contributed by Barney Gale in :gh:`73991`.) * Add :meth:`pathlib.Path.copytree`, which copies one directory tree to another. (Contributed by Barney Gale in :gh:`73991`.) 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`.) 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 ========== * 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`.) * :term:`Soft deprecate ` :func:`os.popen` and :func:`os.spawn* ` 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`.) 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`.) 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`.) Removed ------- * Creating :c:data:`immutable types ` with mutable bases was deprecated since 3.12 and now raises a :exc:`TypeError`.