4.12.0
This release focuses on compatibility with the upcoming release of
Python 3.13. Most changes are related to the implementation of type
parameter defaults (PEP 696).
Thanks to all of the people who contributed patches, especially Alex
Waygood, who did most of the work adapting typing-extensions to the
CPython PEP 696 implementation.
There is a single change since 4.12.0rc1:
- Fix incorrect behaviour of
typing_extensions.ParamSpec
on Python 3.8 and
3.9 that meant that
isinstance(typing_extensions.ParamSpec("P"), typing.TypeVar)
would have a
different result in some situations depending on whether or not a profiling
function had been set usingsys.setprofile
. Patch by Alex Waygood.
Changes included in 4.12.0rc1:
- Improve the implementation of type parameter defaults (PEP 696)
- Backport the
typing.NoDefault
sentinel object from Python 3.13.
TypeVars, ParamSpecs and TypeVarTuples without default values now have
their__default__
attribute set to this sentinel value. - TypeVars, ParamSpecs and TypeVarTuples now have a
has_default()
method, matchingtyping.TypeVar
,typing.ParamSpec
and
typing.TypeVarTuple
on Python 3.13+. - TypeVars, ParamSpecs and TypeVarTuples with
default=None
passed to
their constructors now have their__default__
attribute set toNone
at runtime rather thantypes.NoneType
. - Fix most tests for
TypeVar
,ParamSpec
andTypeVarTuple
on Python
3.13.0b1 and newer. - Backport CPython PR #118774,
allowing type parameters without default values to follow those with
default values in some type parameter lists. Patch by Alex Waygood,
backporting a CPython PR by Jelle Zijlstra. - It is now disallowed to use a
TypeVar
with a default value after a
TypeVarTuple
in a type parameter list. This matches the CPython
implementation of PEP 696 on Python 3.13+. - Fix bug in PEP-696 implementation where a default value for a
ParamSpec
would be cast to a tuple if a list was provided.
Patch by Alex Waygood.
- Backport the
- Fix
Protocol
tests on Python 3.13.0a6 and newer. 3.13.0a6 adds a new
__static_attributes__
attribute to all classes in Python,
which broke some assumptions made by the implementation of
typing_extensions.Protocol
. Similarly, 3.13.0b1 adds the new
__firstlineno__
attribute to all classes. - Fix
AttributeError
when usingtyping_extensions.runtime_checkable
in combination withtyping.Protocol
on Python 3.12.2 or newer.
Patch by Alex Waygood. - At runtime,
assert_never
now includes the repr of the argument
in theAssertionError
. Patch by Hashem, backporting of the original
fix python/cpython#91720 by Jelle Zijlstra. - The second and third parameters of
typing_extensions.Generator
,
and the second parameter oftyping_extensions.AsyncGenerator
,
now default toNone
. This matches the behaviour oftyping.Generator
andtyping.AsyncGenerator
on Python 3.13+. typing_extensions.ContextManager
and
typing_extensions.AsyncContextManager
now have an optional second
parameter, which defaults toOptional[bool]
. The new parameter
signifies the return type of the__(a)exit__
method, matching
typing.ContextManager
andtyping.AsyncContextManager
on Python
3.13+.- Backport
types.CapsuleType
from Python 3.13. - Releases are now made using Trusted Publishers
improving the security of the release process. Patch by Jelle Zijlstra.