3.11.rst

What's New In Python 3.11

Release:	|release|
Date:	|today|

This article explains the new features in Python 3.11, compared to 3.10.

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

Summary -- Release highlights

New Features

Other Language Changes

A :exc:`TypeError` is now raised instead of an :exc:`AttributeError` in :meth:`contextlib.ExitStack.enter_context` and :meth:`contextlib.AsyncExitStack.enter_async_context` for objects which do not support the :term:`context manager` or :term:`asynchronous context manager` protocols correspondingly. (Contributed by Serhiy Storchaka in :issue:`44471`.)

• A :exc:`TypeError` is now raised instead of an :exc:`AttributeError` in :keyword:`with` and :keyword:`async with` statements for objects which do not support the :term:`context manager` or :term:`asynchronous context manager` protocols correspondingly. (Contributed by Serhiy Storchaka in :issue:`12022`.)

New Modules

• None yet.

Improved Modules

fractions

Support PEP 515-style initialization of :class:`~fractions.Fraction` from string. (Contributed by Sergey B Kirpichev in :issue:`44258`.)

math

• Add :func:`math.cbrt`: return the cube root of x. (Contributed by Ajith Ramachandran in :issue:`44357`.)
• The behaviour of two :func:`math.pow` corner cases was changed, for consistency with the IEEE 754 specification. The operations math.pow(0.0, -math.inf) and math.pow(-0.0, -math.inf) now return inf. Previously they raised :exc:`ValueError`. (Contributed by Mark Dickinson in :issue:`44339`.)

sqlite3

• You can now disable the authorizer by passing :const:`None` to :meth:`~sqlite3.Connection.set_authorizer`. (Contributed by Erlend E. Aasland in :issue:`44491`.)

Removed

• :class:`smtpd.MailmanProxy` is now removed as it is unusable without an external module, mailman. (Contributed by Dong-hee Na in :issue:`35800`.)

Optimizations

• Compiler now optimizes simple C-style formatting with literal format containing only format codes %s, %r and %a and makes it as fast as corresponding f-string expression. (Contributed by Serhiy Storchaka in :issue:`28307`.)
• "Zero-cost" exceptions are implemented. The cost of try statements is almost eliminated when no exception is raised. (Contributed by Mark Shannon in :issue:`40222`.)
• Method calls with keywords are now faster due to bytecode changes which avoid creating bound method instances. Previously, this optimization was applied only to method calls with purely positional arguments. (Contributed by Ken Jin and Mark Shannon in :issue:`26110`, based on ideas implemented in PyPy.)

CPython bytecode changes

• Added a new :opcode:`CALL_METHOD_KW` opcode. Calls a method in a similar fashion as :opcode:`CALL_METHOD`, but also supports keyword arguments. Works in tandem with :opcode:`LOAD_METHOD`.

Build Changes

Deprecated

Removed

• The :func:`@asyncio.coroutine <asyncio.coroutine>` :term:`decorator` enabling legacy generator-based coroutines to be compatible with async/await code. The function has been deprecated since Python 3.8 and the removal was initially scheduled for Python 3.10. Use :keyword:`async def` instead. (Contributed by Illia Volochii in :issue:`43216`.)
• :class:`asyncio.coroutines.CoroWrapper` used for wrapping legacy generator-based coroutine objects in the debug mode. (Contributed by Illia Volochii in :issue:`43216`.)

Porting to Python 3.11

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

Changes in the Python API

• Prohibited passing non-:class:`concurrent.futures.ThreadPoolExecutor` executors to :meth:`loop.set_default_executor` following a deprecation in Python 3.8. (Contributed by Illia Volochii in :issue:`43234`.)

C API Changes

New Features

Porting to Python 3.11

• The :c:func:`PyType_Ready` function now raises an error if a type is defined with the :const:`Py_TPFLAGS_HAVE_GC` flag set but has no traverse function (:c:member:`PyTypeObject.tp_traverse`). (Contributed by Victor Stinner in :issue:`44263`.)
• Types with the :const:`Py_TPFLAGS_IMMUTABLETYPE` flag can now inherit the PEP 590 vectorcall protocol. Previously, this was only possible for :ref:`static types <static-types>`. (Contributed by Erlend E. Aasland in :issue:`43908`)

Deprecated

Removed

• :c:func:`PyFrame_BlockSetup` and :c:func:`PyFrame_BlockPop` have been removed. (Contributed by Mark Shannon in :issue:`40222`.)

• Deprecate the following functions to configure the Python initialization:

  • :c:func:`PySys_AddWarnOptionUnicode`
  • :c:func:`PySys_AddWarnOption`
  • :c:func:`PySys_AddXOption`
  • :c:func:`PySys_HasWarnOptions`
  • :c:func:`Py_SetPath`
  • :c:func:`Py_SetProgramName`
  • :c:func:`Py_SetPythonHome`
  • :c:func:`Py_SetStandardStreamEncoding`
  • :c:func:`_Py_SetProgramFullPath`

  Use the new :c:type:`PyConfig` API of the :ref:`Python Initialization Configuration <init-config>` instead (PEP 587). (Contributed by Victor Stinner in :issue:`44113`.)

• The following deprecated functions and methods are removed in the :mod:`gettext` module: :func:`~gettext.lgettext`, :func:`~gettext.ldgettext`, :func:`~gettext.lngettext` and :func:`~gettext.ldngettext`.

  Function :func:`~gettext.bind_textdomain_codeset`, methods :meth:`~gettext.NullTranslations.output_charset` and :meth:`~gettext.NullTranslations.set_output_charset`, and the codeset parameter of functions :func:`~gettext.translation` and :func:`~gettext.install` are also removed, since they are only used for the l*gettext() functions. (Contributed by Dong-hee Na and Serhiy Storchaka in :issue:`44235`.)