gh-103629: Update typing.Unpack docs in compliance with PEP 692 (#103894)

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Franek Magiera 2023-04-27 00:39:39 +02:00 committed by GitHub
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@ -98,6 +98,9 @@ annotations. These include:
*Introducing* :data:`LiteralString`
* :pep:`681`: Data Class Transforms
*Introducing* the :func:`@dataclass_transform<dataclass_transform>` decorator
* :pep:`692`: Using ``TypedDict`` for more precise ``**kwargs`` typing
*Introducing* a new way of typing ``**kwargs`` with :data:`Unpack` and
:data:`TypedDict`
* :pep:`698`: Adding an override decorator to typing
*Introducing* the :func:`@override<override>` decorator
@ -1417,8 +1420,10 @@ These are not used in annotations. They are building blocks for creating generic
tup: tuple[Unpack[Ts]]
In fact, ``Unpack`` can be used interchangeably with ``*`` in the context
of types. You might see ``Unpack`` being used explicitly in older versions
of Python, where ``*`` couldn't be used in certain places::
of :class:`typing.TypeVarTuple <TypeVarTuple>` and
:class:`builtins.tuple <tuple>` types. You might see ``Unpack`` being used
explicitly in older versions of Python, where ``*`` couldn't be used in
certain places::
# In older versions of Python, TypeVarTuple and Unpack
# are located in the `typing_extensions` backports package.
@ -1428,6 +1433,21 @@ These are not used in annotations. They are building blocks for creating generic
tup: tuple[*Ts] # Syntax error on Python <= 3.10!
tup: tuple[Unpack[Ts]] # Semantically equivalent, and backwards-compatible
``Unpack`` can also be used along with :class:`typing.TypedDict` for typing
``**kwargs`` in a function signature::
from typing import TypedDict, Unpack
class Movie(TypedDict):
name: str
year: int
# This function expects two keyword arguments - `name` of type `str`
# and `year` of type `int`.
def foo(**kwargs: Unpack[Movie]): ...
See :pep:`692` for more details on using ``Unpack`` for ``**kwargs`` typing.
.. versionadded:: 3.11
.. class:: ParamSpec(name, *, bound=None, covariant=False, contravariant=False)

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@ -66,6 +66,10 @@ Summary -- Release highlights
.. PEP-sized items next.
New typing features:
* :ref:`whatsnew312-pep692`
Important deprecations, removals or restrictions:
* :pep:`623`, Remove wstr from Unicode
@ -145,6 +149,36 @@ New Features
In Python 3.14, the default will switch to ``'data'``.
(Contributed by Petr Viktorin in :pep:`706`.)
New Features Related to Type Hints
==================================
This section covers major changes affecting :pep:`484` type hints and
the :mod:`typing` module.
.. _whatsnew312-pep692:
PEP 692: Using ``TypedDict`` for more precise ``**kwargs`` typing
-----------------------------------------------------------------
Typing ``**kwargs`` in a function signature as introduced by :pep:`484` allowed
for valid annotations only in cases where all of the ``**kwargs`` were of the
same type.
This PEP specifies a more precise way of typing ``**kwargs`` by relying on
typed dictionaries::
from typing import TypedDict, Unpack
class Movie(TypedDict):
name: str
year: int
def foo(**kwargs: Unpack[Movie]): ...
See :pep:`692` for more details.
(PEP written by Franek Magiera)
Other Language Changes
======================

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@ -0,0 +1,2 @@
Mention the new way of typing ``**kwargs`` with ``Unpack`` and ``TypedDict``
introduced in :pep:`692`.