[Python-checkins] Clarify that Type[SomeTypeVar] is legal (GH-9585)

[Miss Islington (bot)]

https://github.com/python/cpython/commit/dfa11135ce53967ac97550d0a9343d32c9958ac0
commit: dfa11135ce53967ac97550d0a9343d32c9958ac0
branch: 3.6
author: Miss Islington (bot) <31488909+miss-islington at users.noreply.github.com>
committer: GitHub <noreply at github.com>
date: 2018-09-26T08:23:23-07:00
summary:

Clarify that Type[SomeTypeVar] is legal (GH-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).
(cherry picked from commit 130717fe58abb2ab9e7938207df0c130a2562747)

Co-authored-by: Michael Lee <michael.lee.0x2a at gmail.com>

files:
M Doc/library/typing.rst

diff --git a/Doc/library/typing.rst b/Doc/library/typing.rst
index 91d8a5fcf788..e80cd3f2d75c 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]]): ...