Backport types.CapsuleType (#390)

AlexWaygood · web-flow · commit 12a0f286e681 · 2024-05-14T21:10:32.000-04:00
diff --git a/CHANGELOG.md b/CHANGELOG.md
@@ -32,6 +32,7 @@
   signifies the return type of the `__(a)exit__` method, matching
   `typing.ContextManager` and `typing.AsyncContextManager` on Python
   3.13+.
+- Backport `types.CapsuleType` from Python 3.13.
 
 # Release 4.11.0 (April 5, 2024)
 
diff --git a/doc/index.rst b/doc/index.rst
@@ -882,6 +882,20 @@ Annotation metadata
       The documentation string passed to :class:`Doc`.
 
 
+Capsule objects
+~~~~~~~~~~~~~~~
+
+.. class:: CapsuleType
+
+   The type of :py:ref:`capsule objects <capsules>`.
+   See :py:class:`types.CapsuleType`, where it has existed since Python 3.13.
+
+   Note that this may not exist on all implementations of Python; it is only
+   guaranteed to exist on CPython.
+
+   .. versionadded:: 4.12.0
+
+
 Pure aliases
 ~~~~~~~~~~~~
 
diff --git a/src/test_typing_extensions.py b/src/test_typing_extensions.py
@@ -6765,5 +6765,15 @@ def test_pickle(self):
             self.assertEqual(doc_info, pickle.loads(pickled))
 
 
+@skipUnless(
+    hasattr(typing_extensions, "CapsuleType"),
+    "CapsuleType is not available on all Python implementations"
+)
+class CapsuleTypeTests(BaseTestCase):
+    def test_capsule_type(self):
+        import _datetime
+        self.assertIsInstance(_datetime.datetime_CAPI, typing_extensions.CapsuleType)
+
+
 if __name__ == '__main__':
     main()
diff --git a/src/typing_extensions.py b/src/typing_extensions.py
@@ -3411,6 +3411,23 @@ def __eq__(self, other: object) -> bool:
             return self.documentation == other.documentation
 
 
+_CapsuleType = getattr(_types, "CapsuleType", None)
+
+if _CapsuleType is None:
+    try:
+        import _socket
+    except ImportError:
+        pass
+    else:
+        _CAPI = getattr(_socket, "CAPI", None)
+        if _CAPI is not None:
+            _CapsuleType = type(_CAPI)
+
+if _CapsuleType is not None:
+    CapsuleType = _CapsuleType
+    __all__.append("CapsuleType")
+
+
 # Aliases for items that have always been in typing.
 # Explicitly assign these (rather than using `from typing import *` at the top),
 # so that we get a CI error if one of these is deleted from typing.py
