bpo-43923: Add support of multiple inheritance with typing.NamedTuple

serhiy-storchaka · serhiy-storchaka · commit 64f0c5f6ef80 · 2022-04-28T19:47:26.000+03:00
diff --git a/Doc/library/typing.rst b/Doc/library/typing.rst
@@ -1631,7 +1631,7 @@ These are not used in annotations. They are building blocks for declaring types.
       standard ``__annotations__`` attribute which has the same information.
 
    .. versionchanged:: 3.11
-      Added support of multiple inheritance with :class:`Generic`.
+      Added support of multiple inheritence.
 
 .. class:: NewType(name, tp)
 
diff --git a/Doc/whatsnew/3.11.rst b/Doc/whatsnew/3.11.rst
@@ -644,7 +644,7 @@ time
 typing
 ------
 
-* :class:`~typing.NamedTuple` subclasses can be generic.
+* Added support of multiinheritance with :class:`~typing.NamedTuple`.
   (Contributed by Serhiy Storchaka in :issue:`43923`.)
 
 
diff --git a/Lib/test/test_typing.py b/Lib/test/test_typing.py
@@ -5274,10 +5274,38 @@ def _source(self):
 
     def test_multiple_inheritance(self):
         class A:
-            pass
-        with self.assertRaises(TypeError):
-            class X(NamedTuple, A):
-                x: int
+            @property
+            def x(self):
+                return 4
+            @property
+            def y(self):
+                return 5
+            def __len__(self):
+                return 10
+
+        class X(NamedTuple, A):
+            x: int
+        self.assertEqual(X.__bases__, (tuple, A))
+        self.assertEqual(X.__orig_bases__, (NamedTuple, A))
+        self.assertEqual(X.__mro__, (X, tuple, A, object))
+
+        a = X(3)
+        self.assertEqual(a.x, 3)
+        self.assertEqual(a.y, 5)
+        self.assertEqual(len(a), 1)
+
+        class Y(A, NamedTuple):
+            x: int
+        self.assertEqual(Y.__bases__, (A, tuple))
+        self.assertEqual(Y.__orig_bases__, (A, NamedTuple))
+        self.assertEqual(Y.__mro__, (Y, A, tuple, object))
+
+        a = Y(3)
+        self.assertEqual(a.x, 3)
+        self.assertEqual(a.y, 5)
+        self.assertEqual(len(a), 10)
+
+    def test_multiple_inheritance_errors(self):
         with self.assertRaises(TypeError):
             class X(NamedTuple, tuple):
                 x: int
diff --git a/Lib/typing.py b/Lib/typing.py
@@ -2764,10 +2764,6 @@ class NamedTupleMeta(type):
 
     def __new__(cls, typename, bases, ns):
         assert _NamedTuple in bases
-        for base in bases:
-            if base is not _NamedTuple and base is not Generic:
-                raise TypeError('can only inherit from a NamedTuple type '
-                                'and Generic')
         bases = tuple(tuple if base is _NamedTuple else base for base in bases)
         types = ns.get('__annotations__', {})
         default_names = []
diff --git a/Misc/NEWS.d/next/Library/2022-04-28-18-45-58.gh-issue-88089.hu9kRk.rst b/Misc/NEWS.d/next/Library/2022-04-28-18-45-58.gh-issue-88089.hu9kRk.rst
@@ -1,2 +1 @@
-Add support of multiple inheritance of :class:`typing.NamedTuple` with
-:class:`typing.Generic`.
+Add support of multiple inheritance with :class:`typing.NamedTuple`.

Original file line number	Diff line number	Diff line change
`@@ -1,2 +1 @@`
`1`		-Add support of multiple inheritance of :class:`typing.NamedTuple` with
`2`		-:class:`typing.Generic`.
	`1`	+Add support of multiple inheritance with :class:`typing.NamedTuple`.