[Python-checkins] Clarify that Type[SomeTypeVar] is legal (#9585)
Ivan Levkivskyi
webhook-mailer at python.org
Wed Sep 26 11:13:33 EDT 2018
https://github.com/python/cpython/commit/130717fe58abb2ab9e7938207df0c130a2562747
commit: 130717fe58abb2ab9e7938207df0c130a2562747
branch: master
author: Michael Lee <michael.lee.0x2a at gmail.com>
committer: Ivan Levkivskyi <levkivskyi at gmail.com>
date: 2018-09-26T16:13:28+01:00
summary:
Clarify that Type[SomeTypeVar] is legal (#9585)
Currently, the docs state that when doing `Type[X]`, X is only allowed to
be a class, a union of classes, and Any. This pull request amends
that sentence to clarify X may also be a typevar (or a union involving
classes, Any, and TypeVars).
files:
M Doc/library/typing.rst
diff --git a/Doc/library/typing.rst b/Doc/library/typing.rst
index 23a64156c592..268adc0c9de5 100644
--- a/Doc/library/typing.rst
+++ b/Doc/library/typing.rst
@@ -169,6 +169,8 @@ It is possible to declare the return type of a callable without specifying
the call signature by substituting a literal ellipsis
for the list of arguments in the type hint: ``Callable[..., ReturnType]``.
+.. _generics:
+
Generics
--------
@@ -183,7 +185,7 @@ subscription to denote expected types for container elements.
def notify_by_email(employees: Sequence[Employee],
overrides: Mapping[str, str]) -> None: ...
-Generics can be parametrized by using a new factory available in typing
+Generics can be parameterized by using a new factory available in typing
called :class:`TypeVar`.
::
@@ -488,8 +490,9 @@ The module defines the following classes, functions and decorators:
required to handle this particular case may change in future revisions of
:pep:`484`.
- The only legal parameters for :class:`Type` are classes, unions of classes, and
- :data:`Any`. For example::
+ The only legal parameters for :class:`Type` are classes, :data:`Any`,
+ :ref:`type variables <generics>`, and unions of any of these types.
+ For example::
def new_non_team_user(user_class: Type[Union[BaseUser, ProUser]]): ...
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