Docs: Use PEP 585 syntax in "The type of class objects" (#12516)

Author: AlexWaygood

docs/source/kinds_of_types.rst

@@ -615,10 +615,11 @@ The type of class objects
 <484#the-type-of-class-objects>`.)
 
 Sometimes you want to talk about class objects that inherit from a
-given class.  This can be spelled as :py:class:`Type[C] <typing.Type>` where ``C`` is a
+given class.  This can be spelled as ``type[C]`` (or, on Python 3.8 and lower,
+:py:class:`typing.Type[C] <typing.Type>`) where ``C`` is a
 class.  In other words, when ``C`` is the name of a class, using ``C``
 to annotate an argument declares that the argument is an instance of
-``C`` (or of a subclass of ``C``), but using :py:class:`Type[C] <typing.Type>` as an
+``C`` (or of a subclass of ``C``), but using ``type[C]`` as an
 argument annotation declares that the argument is a class object
 deriving from ``C`` (or ``C`` itself).
 
@@ -649,7 +650,7 @@ you pass it the right class object:
        # (Here we could write the user object to a database)
        return user
 
-How would we annotate this function?  Without :py:class:`~typing.Type` the best we
+How would we annotate this function?  Without the ability to parameterize ``type``, the best we
 could do would be:
 
 .. code-block:: python
@@ -665,14 +666,14 @@ doesn't see that the ``buyer`` variable has type ``ProUser``:
    buyer = new_user(ProUser)
    buyer.pay()  # Rejected, not a method on User
 
-However, using :py:class:`~typing.Type` and a type variable with an upper bound (see
+However, using the ``type[C]`` syntax and a type variable with an upper bound (see
 :ref:`type-variable-upper-bound`) we can do better:
 
 .. code-block:: python
 
    U = TypeVar('U', bound=User)
 
-   def new_user(user_class: Type[U]) -> U:
+   def new_user(user_class: type[U]) -> U:
        # Same  implementation as before
 
 Now mypy will infer the correct type of the result when we call
@@ -685,12 +686,12 @@ Now mypy will infer the correct type of the result when we call
 
 .. note::
 
-   The value corresponding to :py:class:`Type[C] <typing.Type>` must be an actual class
+   The value corresponding to ``type[C]`` must be an actual class
    object that's a subtype of ``C``.  Its constructor must be
    compatible with the constructor of ``C``.  If ``C`` is a type
    variable, its upper bound must be a class object.
 
-For more details about ``Type[]`` see :pep:`PEP 484: The type of
+For more details about ``type[]`` and :py:class:`typing.Type[] <typing.Type>`, see :pep:`PEP 484: The type of
 class objects <484#the-type-of-class-objects>`.
 
 .. _text-and-anystr: