Apr 23, 2023 · Feb 11, 2023 · Feb 11, 2023 · Feb 11, 2023 · Feb 11, 2023 · Feb 11, 2023
diff --git a/Doc/library/types.rst b/Doc/library/types.rst

   :pep:`560` - Core support for typing module and generic types

 .. function:: get_original_bases(cls, /)

    Return the objects in the bases list of the class's definition as they
    existed prior to any modification by :meth:`~object.__mro_entries__`. This
    is useful for introspecting :ref:`Generics <user-defined-generics>`.

    Examples::

        from typing import TypeVar, Generic

        T = TypeVar("T")
        class Foo(Generic[T]): ...
        class Bar(Foo[int], float): ...
        class Baz(list[str]): ...

        Foo.__bases__ == (Generic,)
        get_original_bases(Foo) == (Generic[T],)

        Bar.__bases__ == (Foo, float)
        get_original_bases(Bar) == (Foo[int], float)

        Baz.__bases__ == (list,)
        get_original_bases(Baz) == (list[str],)

        get_original_bases(int) == None

    .. versionadded:: 3.12


 Standard Interpreter Types
 --------------------------
diff --git a/Doc/whatsnew/3.12.rst b/Doc/whatsnew/3.12.rst
  profiling functions in all running threads in addition to the calling one.
  (Contributed by Pablo Galindo in :gh:`93503`.)

 types
 -----

 * Add :func:`types.get_original_bases` to allow for further introspection of
  :ref:`user-defined-generics` when subclassed. (Contributed by
  James Hilton-Balfe and Alex Waygood in :gh:`101827`.)

 unicodedata
 -----------

diff --git a/Lib/test/test_types.py b/Lib/test/test_types.py
        D = types.new_class('D', (A(), C, B()), {})
        self.assertEqual(D.__bases__, (A1, A2, A3, C, B1, B2))

    def test_get_original_bases(self):
        T = typing.TypeVar('T')
        class A: pass
        class B(typing.Generic[T]): pass
        class C(B[int]): pass
        class D(B[str], float): pass
        self.assertIsNone(types.get_original_bases(A))
        self.assertEqual(types.get_original_bases(B), (typing.Generic[T],))
        self.assertEqual(types.get_original_bases(C), (B[int],))
        self.assertIsNone(types.get_original_bases(int))
        self.assertEqual(types.get_original_bases(D), (B[str], float))

        class E(list[T]): pass
        class F(list[int]): pass

        self.assertEqual(types.get_original_bases(E), (list[T],))
        self.assertEqual(types.get_original_bases(F), (list[int],))

        class G(typing.NamedTuple):
            x: int

        self.assertIs(types.get_original_bases(G)[0], typing.NamedTuple)

    # Many of the following tests are derived from test_descr.py
    def test_prepare_class(self):
        # Basic test of metaclass derivation
diff --git a/Lib/types.py b/Lib/types.py
                        "of the metaclasses of all its bases")
    return winner


 def get_original_bases(cls, /):
    """Return the class's "original" bases prior to modification by `__mro_entries__`.

    This is useful for introspecting Generics.

    Examples::

        from typing import TypeVar, Generic

        T = TypeVar("T")
        class Foo(Generic[T]): ...
        class Bar(Foo[int], float): ...
        class Baz(list[str]): ...

        get_original_bases(Foo) == (Generic[T],)
        get_original_bases(Bar) == (Foo[int], float)
        get_original_bases(Baz) == (list[str],)
        get_original_bases(int) == None
    """
    if isinstance(cls, type):
        try:
            return cls.__orig_bases__
        except AttributeError:
            pass
    return None


 class DynamicClassAttribute:
    """Route attribute access on a class to __getattr__.

diff --git a/Misc/NEWS.d/next/Library/2023-02-11-15-01-32.gh-issue-101688.kwXmfM.rst b/Misc/NEWS.d/next/Library/2023-02-11-15-01-32.gh-issue-101688.kwXmfM.rst
 Implement :func:`types.get_original_bases` to provide further introspection
 for types.
Original file line number	Diff line number	Diff line change
Expand Up		@@ -388,6 +388,13 @@ threading
		profiling functions in all running threads in addition to the calling one.
		(Contributed by Pablo Galindo in :gh:`93503`.)

		types
		-----

		* Add :func:`types.get_original_bases` to allow for further introspection of
		:ref:`user-defined-generics` when subclassed. (Contributed by
		James Hilton-Balfe and Alex Waygood in :gh:`101827`.)

		unicodedata
		-----------

Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -1360,6 +1360,29 @@ class C: pass
		D = types.new_class('D', (A(), C, B()), {})
		self.assertEqual(D.__bases__, (A1, A2, A3, C, B1, B2))

		def test_get_original_bases(self):
		T = typing.TypeVar('T')
		class A: pass
		class B(typing.Generic[T]): pass
		class C(B[int]): pass
		class D(B[str], float): pass
		self.assertIsNone(types.get_original_bases(A))
		self.assertEqual(types.get_original_bases(B), (typing.Generic[T],))
		self.assertEqual(types.get_original_bases(C), (B[int],))
		self.assertIsNone(types.get_original_bases(int))
		self.assertEqual(types.get_original_bases(D), (B[str], float))

		class E(list[T]): pass
		class F(list[int]): pass

		self.assertEqual(types.get_original_bases(E), (list[T],))
		self.assertEqual(types.get_original_bases(F), (list[int],))

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		class G(typing.NamedTuple):
		x: int

		self.assertIs(types.get_original_bases(G)[0], typing.NamedTuple)

		# Many of the following tests are derived from test_descr.py
		def test_prepare_class(self):
		# Basic test of metaclass derivation
Expand Down
Original file line number	Diff line number	Diff line change
Expand Up		@@ -143,6 +143,34 @@ def _calculate_meta(meta, bases):
		"of the metaclasses of all its bases")
		return winner


		def get_original_bases(cls, /):
		"""Return the class's "original" bases prior to modification by `__mro_entries__`.

		This is useful for introspecting Generics.

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		Examples::

		from typing import TypeVar, Generic

		T = TypeVar("T")
		class Foo(Generic[T]): ...
		class Bar(Foo[int], float): ...
		class Baz(list[str]): ...

		get_original_bases(Foo) == (Generic[T],)
		get_original_bases(Bar) == (Foo[int], float)
		get_original_bases(Baz) == (list[str],)
		get_original_bases(int) == None
		"""
		if isinstance(cls, type):
		try:
		return cls.__orig_bases__
		except AttributeError:
		pass
		return None
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		class DynamicClassAttribute:
		"""Route attribute access on a class to __getattr__.

Expand Down
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		Implement :func:`types.get_original_bases` to provide further introspection
		for types.