Type aliases supported.

Refs #121.

CHANGELOG.md

@@ -7,6 +7,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/).
 ### Changed
 * `multidispatch` supports variable keyword arguments
 * `multidispatch` base implementation always matches
+* Type aliases supported
 
 ## [1.11.2](https://pypi.org/project/multimethod/1.11.2/) - 2024-02-27
 ### Fixed

multimethod/__init__.py

@@ -46,6 +46,8 @@ def __new__(cls, tp, *args):
             return object
         if hasattr(tp, '__supertype__'):  # isinstance(..., NewType) only supported >=3.10
             tp = tp.__supertype__
+        if hasattr(typing, 'TypeAliasType') and isinstance(tp, typing.TypeAliasType):
+            tp = tp.__value__
         if isinstance(tp, TypeVar):
             if not tp.__constraints__:
                 return object

tests/test_subscripts.py

@@ -36,6 +36,12 @@ def test_union():
     assert issubclass(subtype(int | float), subtype(int | float | None))
 
 
+@pytest.mark.skipif(sys.version_info < (3, 12), reason="Type aliases added in 3.12")
+def test_type_alias():
+    Point = typing.TypeAliasType(name='Point', value=tuple[int, int])
+    assert isinstance((0, 0), subtype(Point))
+
+
 def test_type():
     @multimethod
     def func(arg: Type[int]):