diff --git a/Lib/inspect.py b/Lib/inspect.py index 0a57749ccdd458..c2a1ed4148e749 100644 --- a/Lib/inspect.py +++ b/Lib/inspect.py @@ -2367,7 +2367,7 @@ def _signature_from_callable(obj, *, if (obj.__init__ is object.__init__ and obj.__new__ is object.__new__): # Return a signature of 'object' builtin. - return signature(object) + return sigcls.from_callable(object) else: raise ValueError( 'no signature found for builtin type {!r}'.format(obj)) diff --git a/Lib/test/test_inspect.py b/Lib/test/test_inspect.py index 1cd4ea28939d8a..db9ac36f7198e5 100644 --- a/Lib/test/test_inspect.py +++ b/Lib/test/test_inspect.py @@ -3157,14 +3157,21 @@ def test_signature_from_callable_python_obj(self): class MySignature(inspect.Signature): pass def foo(a, *, b:1): pass foo_sig = MySignature.from_callable(foo) - self.assertTrue(isinstance(foo_sig, MySignature)) + self.assertIsInstance(foo_sig, MySignature) + + def test_signature_from_callable_class(self): + # A regression test for a class inheriting its signature from `object`. + class MySignature(inspect.Signature): pass + class foo: pass + foo_sig = MySignature.from_callable(foo) + self.assertIsInstance(foo_sig, MySignature) @unittest.skipIf(MISSING_C_DOCSTRINGS, "Signature information for builtins requires docstrings") def test_signature_from_callable_builtin_obj(self): class MySignature(inspect.Signature): pass sig = MySignature.from_callable(_pickle.Pickler) - self.assertTrue(isinstance(sig, MySignature)) + self.assertIsInstance(sig, MySignature) def test_signature_definition_order_preserved_on_kwonly(self): for fn in signatures_with_lexicographic_keyword_only_parameters(): diff --git a/Misc/NEWS.d/next/Library/2019-09-13-14-54-33.bpo-34706.HWVpOY.rst b/Misc/NEWS.d/next/Library/2019-09-13-14-54-33.bpo-34706.HWVpOY.rst new file mode 100644 index 00000000000000..1df3742abd272f --- /dev/null +++ b/Misc/NEWS.d/next/Library/2019-09-13-14-54-33.bpo-34706.HWVpOY.rst @@ -0,0 +1 @@ +Preserve subclassing in inspect.Signature.from_callable.