CHANGELOG.md

Unreleased

• Speedup issubclass() checks against simple runtime-checkable protocols by around 6% (backporting python/cpython#112717, by Alex Waygood).
• Fix a regression in the implementation of protocols where typing.Protocol classes that were not marked as @runtime_checkable would be unnecessarily introspected, potentially causing exceptions to be raised if the protocol had problematic members. Patch by Alex Waygood, backporting python/cpython#113401.

Release 4.9.0 (December 9, 2023)

This feature release adds typing_extensions.ReadOnly, as specified by PEP 705, and makes various other improvements, especially to @typing_extensions.deprecated().

There are no changes since 4.9.0rc1.

Release 4.9.0rc1 (November 29, 2023)

• Add support for PEP 705, adding typing_extensions.ReadOnly. Patch by Jelle Zijlstra.
• All parameters on NewType.__call__ are now positional-only. This means that the signature of typing_extensions.NewType.__call__ now exactly matches the signature of typing.NewType.__call__. Patch by Alex Waygood.
• Fix bug with using @deprecated on a mixin class. Inheriting from a deprecated class now raises a DeprecationWarning. Patch by Jelle Zijlstra.
• @deprecated now gives a better error message if you pass a non-str argument to the msg parameter. Patch by Alex Waygood.
• @deprecated is now implemented as a class for better introspectability. Patch by Jelle Zijlstra.
• Exclude __match_args__ from Protocol members. Backport of python/cpython#110683 by Nikita Sobolev.
• When creating a typing_extensions.NamedTuple class, ensure __set_name__ is called on all objects that define __set_name__ and exist in the values of the NamedTuple class's class dictionary. Patch by Alex Waygood, backporting python/cpython#111876.
• Improve the error message when trying to call issubclass() against a Protocol that has non-method members. Patch by Alex Waygood (backporting python/cpython#112344, by Randolph Scholz).

Release 4.8.0 (September 17, 2023)

No changes since 4.8.0rc1.

Release 4.8.0rc1 (September 7, 2023)

• Add typing_extensions.Doc, as proposed by PEP 727. Patch by Sebastián Ramírez.
• Drop support for Python 3.7 (including PyPy-3.7). Patch by Alex Waygood.
• Fix bug where get_original_bases() would return incorrect results when called on a concrete subclass of a generic class. Patch by Alex Waygood (backporting python/cpython#107584, by James Hilton-Balfe).
• Fix bug where ParamSpec(default=...) would raise a TypeError on Python versions <3.11. Patch by James Hilton-Balfe

Release 4.7.1 (July 2, 2023)

• Fix support for TypedDict, NamedTuple and is_protocol on PyPy-3.7 and PyPy-3.8. Patch by Alex Waygood. Note that PyPy-3.7 and PyPy-3.8 are unsupported by the PyPy project. The next feature release of typing-extensions will drop support for PyPy-3.7 and may also drop support for PyPy-3.8.

Release 4.7.0 (June 28, 2023)

• This is expected to be the last feature release supporting Python 3.7, which reaches its end of life on June 27, 2023. Version 4.8.0 will support only Python 3.8.0 and up.
• Fix bug where a typing_extensions.Protocol class that had one or more non-callable members would raise TypeError when issubclass() was called against it, even if it defined a custom __subclasshook__ method. The correct behaviour -- which has now been restored -- is not to raise TypeError in these situations if a custom __subclasshook__ method is defined. Patch by Alex Waygood (backporting python/cpython#105976).

Release 4.7.0rc1 (June 21, 2023)

• Add typing_extensions.get_protocol_members and typing_extensions.is_protocol (backport of CPython PR #104878). Patch by Jelle Zijlstra.
• typing_extensions now re-exports all names in the standard library's typing module, except the deprecated ByteString. Patch by Jelle Zijlstra.
• Due to changes in the implementation of typing_extensions.Protocol, typing.runtime_checkable can now be used on typing_extensions.Protocol (previously, users had to use typing_extensions.runtime_checkable if they were using typing_extensions.Protocol).
• Align the implementation of TypedDict with the implementation in the standard library on Python 3.9 and higher. typing_extensions.TypedDict is now a function instead of a class. The private functions _check_fails, _dict_new, and _typeddict_new have been removed. is_typeddict now returns False when called with TypedDict itself as the argument. Patch by Jelle Zijlstra.
• Declare support for Python 3.12. Patch by Jelle Zijlstra.
• Fix tests on Python 3.13, which removes support for creating TypedDict classes through the keyword-argument syntax. Patch by Jelle Zijlstra.
• Fix a regression introduced in v4.6.3 that meant that issubclass(object, typing_extensions.Protocol) would erroneously raise TypeError. Patch by Alex Waygood (backporting the CPython PR python/cpython#105239).
• Allow Protocol classes to inherit from typing_extensions.Buffer or collections.abc.Buffer. Patch by Alex Waygood (backporting python/cpython#104827, by Jelle Zijlstra).
• Allow classes to inherit from both typing.Protocol and typing_extensions.Protocol simultaneously. Since v4.6.0, this caused TypeError to be raised due to a metaclass conflict. Patch by Alex Waygood.
• Backport several deprecations from CPython relating to unusual ways to create TypedDicts and NamedTuples. CPython PRs #105609 and #105780 by Alex Waygood; typing_extensions backport by Jelle Zijlstra.
  • Creating a NamedTuple using the functional syntax with keyword arguments (NT = NamedTuple("NT", a=int)) is now deprecated.
  • Creating a NamedTuple with zero fields using the syntax NT = NamedTuple("NT") or NT = NamedTuple("NT", None) is now deprecated.
  • Creating a TypedDict with zero fields using the syntax TD = TypedDict("TD") or TD = TypedDict("TD", None) is now deprecated.
• Fix bug on Python 3.7 where a protocol X that had a member a would not be considered an implicit subclass of an unrelated protocol Y that only has a member a. Where the members of X are a superset of the members of Y, X should always be considered a subclass of Y iff Y is a runtime-checkable protocol that only has callable members. Patch by Alex Waygood (backporting CPython PR python/cpython#105835).

Release 4.6.3 (June 1, 2023)

• Fix a regression introduced in v4.6.0 in the implementation of runtime-checkable protocols. The regression meant that doing class Foo(X, typing_extensions.Protocol), where X was a class that had abc.ABCMeta as its metaclass, would then cause subsequent isinstance(1, X) calls to erroneously raise TypeError. Patch by Alex Waygood (backporting the CPython PR python/cpython#105152).
• Sync the repository's LICENSE file with that of CPython. typing_extensions is distributed under the same license as CPython itself.
• Skip a problematic test on Python 3.12.0b1. The test fails on 3.12.0b1 due to a bug in CPython, which will be fixed in 3.12.0b2. The typing_extensions test suite now passes on 3.12.0b1.

Release 4.6.2 (May 25, 2023)

• Fix use of @deprecated on classes with __new__ but no __init__. Patch by Jelle Zijlstra.
• Fix regression in version 4.6.1 where comparing a generic class against a runtime-checkable protocol using isinstance() would cause AttributeError to be raised if using Python 3.7.

Release 4.6.1 (May 23, 2023)

• Change deprecated @runtime to formal API @runtime_checkable in the error message. Patch by Xuehai Pan.
• Fix regression in 4.6.0 where attempting to define a Protocol that was generic over a ParamSpec or a TypeVarTuple would cause TypeError to be raised. Patch by Alex Waygood.

Release 4.6.0 (May 22, 2023)

• typing_extensions is now documented at https://typing-extensions.readthedocs.io/en/latest/. Patch by Jelle Zijlstra.

• Add typing_extensions.Buffer, a marker class for buffer types, as proposed by PEP 688. Equivalent to collections.abc.Buffer in Python 3.12. Patch by Jelle Zijlstra.

• Backport two CPython PRs fixing various issues with typing.Literal: python/cpython#23294 and python/cpython#23383. Both CPython PRs were originally by Yurii Karabas, and both were backported to Python >=3.9.1, but no earlier. Patch by Alex Waygood.

  A side effect of one of the changes is that equality comparisons of Literal objects will now raise a TypeError if one of the Literal objects being compared has a mutable parameter. (Using mutable parameters with Literal is not supported by PEP 586 or by any major static type checkers.)

• Literal is now reimplemented on all Python versions <= 3.10.0. The typing_extensions version does not suffer from the bug that was fixed in python/cpython#29334. (The CPython bugfix was backported to CPython 3.10.1 and 3.9.8, but no earlier.)

• Backport CPython PR 26067 (originally by Yurii Karabas), ensuring that isinstance() calls on protocols raise TypeError when the protocol is not decorated with @runtime_checkable. Patch by Alex Waygood.

• Backport several significant performance improvements to runtime-checkable protocols that have been made in Python 3.12 (see python/cpython#74690 for details). Patch by Alex Waygood.

  A side effect of one of the performance improvements is that the members of a runtime-checkable protocol are now considered “frozen” at runtime as soon as the class has been created. Monkey-patching attributes onto a runtime-checkable protocol will still work, but will have no impact on isinstance() checks comparing objects to the protocol. See "What's New in Python 3.12" for more details.

• isinstance() checks against runtime-checkable protocols now use inspect.getattr_static() rather than hasattr() to lookup whether attributes exist (backporting python/cpython#103034). This means that descriptors and __getattr__ methods are no longer unexpectedly evaluated during isinstance() checks against runtime-checkable protocols. However, it may also mean that some objects which used to be considered instances of a runtime-checkable protocol on older versions of typing_extensions may no longer be considered instances of that protocol using the new release, and vice versa. Most users are unlikely to be affected by this change. Patch by Alex Waygood.

• Backport the ability to define __init__ methods on Protocol classes, a change made in Python 3.11 (originally implemented in python/cpython#31628 by Adrian Garcia Badaracco). Patch by Alex Waygood.

• Speedup isinstance(3, typing_extensions.SupportsIndex) by >10x on Python <3.12. Patch by Alex Waygood.

• Add typing_extensions versions of SupportsInt, SupportsFloat, SupportsComplex, SupportsBytes, SupportsAbs and SupportsRound. These have the same semantics as the versions from the typing module, but isinstance() checks against the typing_extensions versions are >10x faster at runtime on Python <3.12. Patch by Alex Waygood.

• Add __orig_bases__ to non-generic TypedDicts, call-based TypedDicts, and call-based NamedTuples. Other TypedDicts and NamedTuples already had the attribute. Patch by Adrian Garcia Badaracco.

• Add typing_extensions.get_original_bases, a backport of types.get_original_bases, introduced in Python 3.12 (CPython PR python/cpython#101827, originally by James Hilton-Balfe). Patch by Alex Waygood.

  This function should always produce correct results when called on classes constructed using features from typing_extensions. However, it may produce incorrect results when called on some NamedTuple or TypedDict classes that use typing.{NamedTuple,TypedDict} on Python <=3.11.

• Constructing a call-based TypedDict using keyword arguments for the fields now causes a DeprecationWarning to be emitted. This matches the behaviour of typing.TypedDict on 3.11 and 3.12.

• Backport the implementation of NewType from 3.10 (where it is implemented as a class rather than a function). This allows user-defined NewTypes to be pickled. Patch by Alex Waygood.

• Fix tests and import on Python 3.12, where typing.TypeVar can no longer be subclassed. Patch by Jelle Zijlstra.

• Add typing_extensions.TypeAliasType, a backport of typing.TypeAliasType from PEP 695. Patch by Jelle Zijlstra.

• Backport changes to the repr of typing.Unpack that were made in order to implement PEP 692 (backport of python/cpython#104048). Patch by Alex Waygood.

Release 4.5.0 (February 14, 2023)

• Runtime support for PEP 702, adding typing_extensions.deprecated. Patch by Jelle Zijlstra.
• Add better default value for TypeVar default parameter, PEP 696. Enables runtime check if None was passed as default. Patch by Marc Mueller (@cdce8p).
• The @typing_extensions.override decorator now sets the .__override__ attribute. Patch by Steven Troxler.
• Fix get_type_hints() on cross-module inherited TypedDict in 3.9 and 3.10. Patch by Carl Meyer.
• Add frozen_default parameter on dataclass_transform. Patch by Erik De Bonte.

Release 4.4.0 (October 6, 2022)

• Add typing_extensions.Any a backport of python 3.11's Any class which is subclassable at runtime. (backport from python/cpython#31841, by Shantanu and Jelle Zijlstra). Patch by James Hilton-Balfe (@Gobot1234).
• Add initial support for TypeVarLike default parameter, PEP 696. Patch by Marc Mueller (@cdce8p).
• Runtime support for PEP 698, adding typing_extensions.override. Patch by Jelle Zijlstra.
• Add the infer_variance parameter to TypeVar, as specified in PEP 695. Patch by Jelle Zijlstra.

Release 4.3.0 (July 1, 2022)

• Add typing_extensions.NamedTuple, allowing for generic NamedTuples on Python <3.11 (backport from python/cpython#92027, by Serhiy Storchaka). Patch by Alex Waygood (@AlexWaygood).
• Adjust typing_extensions.TypedDict to allow for generic TypedDicts on Python <3.11 (backport from python/cpython#27663, by Samodya Abey). Patch by Alex Waygood (@AlexWaygood).

Release 4.2.0 (April 17, 2022)

• Re-export typing.Unpack and typing.TypeVarTuple on Python 3.11.
• Add ParamSpecArgs and ParamSpecKwargs to __all__.
• Improve "accepts only single type" error messages.
• Improve the distributed package. Patch by Marc Mueller (@cdce8p).
• Update typing_extensions.dataclass_transform to rename the field_descriptors parameter to field_specifiers and accept arbitrary keyword arguments.
• Add typing_extensions.get_overloads and typing_extensions.clear_overloads, and add registry support to typing_extensions.overload. Backport from python/cpython#89263.
• Add typing_extensions.assert_type. Backport from bpo-46480.
• Drop support for Python 3.6. Original patch by Adam Turner (@AA-Turner).

Release 4.1.1 (February 13, 2022)

• Fix importing typing_extensions on Python 3.7.0 and 3.7.1. Original patch by Nikita Sobolev (@sobolevn).

Release 4.1.0 (February 12, 2022)

• Runtime support for PEP 646, adding typing_extensions.TypeVarTuple and typing_extensions.Unpack.
• Add interaction of Required and NotRequired with __required_keys__, __optional_keys__ and get_type_hints(). Patch by David Cabot (@d-k-bo).
• Runtime support for PEP 675 and typing_extensions.LiteralString.
• Add Never and assert_never. Backport from bpo-46475.
• ParamSpec args and kwargs are now equal to themselves. Backport from bpo-46676. Patch by Gregory Beauregard (@GBeauregard).
• Add reveal_type. Backport from bpo-46414.
• Runtime support for PEP 681 and typing_extensions.dataclass_transform.
• Annotated can now wrap ClassVar and Final. Backport from bpo-46491. Patch by Gregory Beauregard (@GBeauregard).
• Add missed Required and NotRequired to __all__. Patch by Yuri Karabas (@uriyyo).
• The @final decorator now sets the __final__ attribute on the decorated object to allow runtime introspection. Backport from bpo-46342.
• Add is_typeddict. Patch by Chris Moradi (@chrismoradi) and James Hilton-Balfe (@Gobot1234).

Release 4.0.1 (November 30, 2021)

• Fix broken sdist in release 4.0.0. Patch by Adam Turner (@AA-Turner).
• Fix equality comparison for Required and NotRequired. Patch by Jelle Zijlstra (@jellezijlstra).
• Fix usage of Self as a type argument. Patch by Chris Wesseling (@CharString) and James Hilton-Balfe (@Gobot1234).

Release 4.0.0 (November 14, 2021)

• Starting with version 4.0.0, typing_extensions uses Semantic Versioning. See the README for more information.
• Dropped support for Python versions 3.5 and older, including Python 2.7.
• Simplified backports for Python 3.6.0 and newer. Patch by Adam Turner (@AA-Turner).

Added in version 4.0.0

• Runtime support for PEP 673 and typing_extensions.Self. Patch by James Hilton-Balfe (@Gobot1234).
• Runtime support for PEP 655 and typing_extensions.Required and NotRequired. Patch by David Foster (@davidfstr).

Removed in version 4.0.0

The following non-exported but non-private names have been removed as they are unneeded for supporting Python 3.6 and newer.

• TypingMeta
• OLD_GENERICS
• SUBS_TREE
• HAVE_ANNOTATED
• HAVE_PROTOCOLS
• V_co
• VT_co

Previous releases

Prior to release 4.0.0 we did not provide a changelog. Please check the Git history for details.