gh-104010: Separate and improve docs for typing.get_origin and typing.get_args

Doc/library/typing.rst

@@ -2881,24 +2881,37 @@ Introspection helpers
  if a default value equal to ``None`` was set.
  Now the annotation is returned unchanged.
 
-.. function:: get_args(tp)
 .. function:: get_origin(tp)
 
- Provide basic introspection for generic types and special typing forms.
-
- For a typing object of the form ``X[Y, Z, ...]`` these functions return
- ``X`` and ``(Y, Z, ...)``. If ``X`` is a generic alias for a builtin or
+ Get the unsubscripted version of a type: for a typing object of the form
+ ``X[Y, Z, ...]`` return ``X``. If ``X`` is a generic alias for a builtin or
  :mod:`collections` class, it gets normalized to the original class.
+ If ``X`` is an instance of :class:`ParamSpecArgs` or :class:`ParamSpecKwargs`,
+ return the underlying :class:`ParamSpec`.
+ Return ``None`` for unsupported objects.
+ Examples::
+
+ assert get_origin(str) is None
+ assert get_origin(Dict[str, int]) is dict
+ assert get_origin(Union[int, str]) is Union
+ P = ParamSpec('P')
+ assert get_origin(P.args) is P
+ assert get_origin(P.kwargs) is P
+
+ .. versionadded:: 3.8
+
+.. function:: get_args(tp)
+
+ Get type arguments with all substitutions performed: for a typing object
+ of the form ``X[Y, Z, ...]`` return ``(Y, Z, ...)``.
  If ``X`` is a union or :class:`Literal` contained in another
  generic type, the order of ``(Y, Z, ...)`` may be different from the order
  of the original arguments ``[Y, Z, ...]`` due to type caching.
- For unsupported objects return ``None`` and ``()`` correspondingly.
+ Return ``()`` for unsupported objects.
  Examples::
 
- assert get_origin(Dict[str, int]) is dict
+ assert get_args(int) == ()
  assert get_args(Dict[int, str]) == (int, str)
-
- assert get_origin(Union[int, str]) is Union
  assert get_args(Union[int, str]) == (int, str)
 
  .. versionadded:: 3.8