diff options
Diffstat (limited to 'Lib/abc.py')
| -rw-r--r-- | Lib/abc.py | 9 |
1 files changed, 5 insertions, 4 deletions
@@ -3,6 +3,7 @@ """Abstract Base Classes (ABCs) according to PEP 3119.""" +from weakref import WeakSet def abstractmethod(funcobj): """A decorator indicating abstract methods. @@ -130,9 +131,9 @@ class ABCMeta(type): abstracts.add(name) cls.__abstractmethods__ = abstracts # Set up inheritance registry - cls._abc_registry = set() - cls._abc_cache = set() - cls._abc_negative_cache = set() + cls._abc_registry = WeakSet() + cls._abc_cache = WeakSet() + cls._abc_negative_cache = WeakSet() cls._abc_negative_cache_version = ABCMeta._abc_invalidation_counter return cls @@ -172,7 +173,7 @@ class ABCMeta(type): # Check negative cache; may have to invalidate if cls._abc_negative_cache_version < ABCMeta._abc_invalidation_counter: # Invalidate the negative cache - cls._abc_negative_cache = set() + cls._abc_negative_cache = WeakSet() cls._abc_negative_cache_version = ABCMeta._abc_invalidation_counter elif subclass in cls._abc_negative_cache: return False |