https://github.com/python/cpython/commit/75ff1afcb6a1bb2b3d54899e9b222a61798fa491
commit: 75ff1afcb6a1bb2b3d54899e9b222a61798fa491
branch: main
author: John Seong <[email protected]>
committer: JelleZijlstra <[email protected]>
date: 2026-04-22T19:46:04-07:00
summary:
gh-142965: Fix Concatenate documentation to reflect valid use cases (#143316)
The documentation previously stated that Concatenate is only valid
when used as the first argument to Callable, but according to PEP 612,
it can also be used when instantiating user-defined generic classes
with ParamSpec parameters.
files:
M Doc/library/typing.rst
diff --git a/Doc/library/typing.rst b/Doc/library/typing.rst
index 9bc0a3caeee8bf..04acf2c16d15d2 100644
--- a/Doc/library/typing.rst
+++ b/Doc/library/typing.rst
@@ -1174,7 +1174,8 @@ These can be used as types in annotations. They all
support subscription using
or transforms parameters of another
callable. Usage is in the form
``Concatenate[Arg1Type, Arg2Type, ..., ParamSpecVariable]``. ``Concatenate``
- is currently only valid when used as the first argument to a :ref:`Callable
<annotating-callables>`.
+ is valid when used in :ref:`Callable <annotating-callables>` type hints
+ and when instantiating user-defined generic classes with :class:`ParamSpec`
parameters.
The last parameter to ``Concatenate`` must be a :class:`ParamSpec` or
ellipsis (``...``).
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