diff options
Diffstat (limited to 'Lib')
| -rw-r--r-- | Lib/abc.py | 16 | ||||
| -rw-r--r-- | Lib/test/test_abc.py | 10 |
2 files changed, 24 insertions, 2 deletions
diff --git a/Lib/abc.py b/Lib/abc.py index 1ce38a81c8..9d15012c30 100644 --- a/Lib/abc.py +++ b/Lib/abc.py @@ -163,8 +163,20 @@ class ABCMeta(type): def __instancecheck__(cls, instance): """Override for isinstance(instance, cls).""" - return any(cls.__subclasscheck__(c) - for c in set([instance.__class__, type(instance)])) + # Inline the cache checking for new-style classes. + subclass = instance.__class__ + if subclass in cls._abc_cache: + return True + subtype = type(instance) + if subtype is subclass: + if (cls._abc_negative_cache_version == + ABCMeta._abc_invalidation_counter and + subclass in cls._abc_negative_cache): + return False + # Fall back to the subclass check. + return cls.__subclasscheck__(subclass) + return (cls.__subclasscheck__(subclass) or + cls.__subclasscheck__(subtype)) def __subclasscheck__(cls, subclass): """Override for issubclass(subclass, cls).""" diff --git a/Lib/test/test_abc.py b/Lib/test/test_abc.py index 272f61df12..ac5f7ee245 100644 --- a/Lib/test/test_abc.py +++ b/Lib/test/test_abc.py @@ -83,6 +83,16 @@ class TestABC(unittest.TestCase): self.assertEqual(issubclass(C, A), True) self.assertEqual(isinstance(c, A), True) + def test_isinstance_invalidation(self): + class A: + __metaclass__ = abc.ABCMeta + class B(object): + pass + b = B() + self.assertEqual(isinstance(b, A), False) + A.register(B) + self.assertEqual(isinstance(b, A), True) + def test_registration_builtins(self): class A: __metaclass__ = abc.ABCMeta |