Merge pull request #21 from erezsh/annotated

Added support for typing_extensions.Annotated

pyproject.toml

@@ -23,6 +23,9 @@ packages = [{ include = "runtype" }]
 python = "^3.6"
 dataclasses = {version = "*", python = "~3.6"}
 
+[tool.poetry.dev-dependencies]
+typing_extensions = "*"
+
 [build-system]
 requires = ["poetry-core>=1.0.0"]
 build-backend = "poetry.core.masonry.api"

runtype/pytypes.py

@@ -27,6 +27,11 @@ def _forwardref_evaluate(self, g, l, _):
 else:
     _forwardref_evaluate = ForwardRef._evaluate
 
+try:
+    import typing_extensions
+except ImportError:
+    typing_extensions = None
+
 
 
 py38 = sys.version_info >= (3, 8)
@@ -367,6 +372,13 @@ def _to_canon(self, t):
         if hasattr(typing, '_AnnotatedAlias') and isinstance(t, typing._AnnotatedAlias):
             return to_canon(t.__origin__)
 
+        if typing_extensions:
+            if hasattr(typing_extensions, '_AnnotatedAlias') and isinstance(t, typing_extensions._AnnotatedAlias):
+                return to_canon(t.__origin__)
+            elif hasattr(typing_extensions, 'AnnotatedMeta') and isinstance(t, typing_extensions.AnnotatedMeta):
+                # Python 3.6
+                return to_canon(t.__args__[0])
+
         try:
             t.__origin__
         except AttributeError:

tests/test_basic.py

@@ -14,6 +14,11 @@
 from runtype import Dispatch, DispatchError, dataclass, isa, is_subtype, issubclass, assert_isa, String, Int, validate_func
 from runtype.dataclass import Configuration
 
+try:
+    import typing_extensions
+except ImportError:
+    typing_extensions = None
+
 
 class TestIsa(TestCase):
     def setUp(self):
@@ -133,6 +138,16 @@ def f(a: List[int] = None):
         f()
         self.assertRaises(TypeError, f, [1, None])
 
+    def test_typing_extensions(self):
+        if typing_extensions is None:
+            logging.info("Skipping tests for typing extensions")
+            return
+
+        a = typing_extensions.Annotated[int, range(1, 10)]
+        assert is_subtype(a, int)
+        assert is_subtype(int, a)
+        assert isa(1, a)
+
 
 
 class TestDispatch(TestCase):