bpo-35341: Add generic version of OrderedDict to typing (GH-10850)

(cherry picked from commit 68b56d0)

Co-authored-by: Ismo Toijala <ismo.toijala@gmail.com>

Doc/library/typing.rst

@@ -689,6 +689,12 @@ The module defines the following classes, functions and decorators:
 
    .. versionadded:: 3.5.2
 
+.. class:: OrderedDict(collections.OrderedDict, MutableMapping[KT, VT])
+
+   A generic version of :class:`collections.OrderedDict`.
+
+   .. versionadded:: 3.7.2
+
 .. class:: Counter(collections.Counter, Dict[T, int])
 
    A generic version of :class:`collections.Counter`.

Lib/test/test_typing.py

@@ -2075,6 +2075,22 @@ class MyDefDict(typing.DefaultDict[str, int]):
         self.assertIsSubclass(MyDefDict, collections.defaultdict)
         self.assertNotIsSubclass(collections.defaultdict, MyDefDict)
 
+    def test_ordereddict_instantiation(self):
+        self.assertIs(type(typing.OrderedDict()), collections.OrderedDict)
+        self.assertIs(type(typing.OrderedDict[KT, VT]()), collections.OrderedDict)
+        self.assertIs(type(typing.OrderedDict[str, int]()), collections.OrderedDict)
+
+    def test_ordereddict_subclass(self):
+
+        class MyOrdDict(typing.OrderedDict[str, int]):
+            pass
+
+        od = MyOrdDict()
+        self.assertIsInstance(od, MyOrdDict)
+
+        self.assertIsSubclass(MyOrdDict, collections.OrderedDict)
+        self.assertNotIsSubclass(collections.OrderedDict, MyOrdDict)
+
     @skipUnless(sys.version_info >= (3, 3), 'ChainMap was added in 3.3')
     def test_chainmap_instantiation(self):
         self.assertIs(type(typing.ChainMap()), collections.ChainMap)

Lib/typing.py

@@ -1242,6 +1242,7 @@ def _alias(origin, params, inst=True):
 AsyncContextManager = _alias(contextlib.AbstractAsyncContextManager, T_co)
 Dict = _alias(dict, (KT, VT), inst=False)
 DefaultDict = _alias(collections.defaultdict, (KT, VT))
+OrderedDict = _alias(collections.OrderedDict, (KT, VT))
 Counter = _alias(collections.Counter, T)
 ChainMap = _alias(collections.ChainMap, (KT, VT))
 Generator = _alias(collections.abc.Generator, (T_co, T_contra, V_co))

Misc/NEWS.d/next/Library/2018-12-02-13-50-52.bpo-35341.32E8T_.rst

@@ -0,0 +1 @@
+Add generic version of ``collections.OrderedDict`` to the ``typing`` module.  Patch by Ismo Toijala.