Issue #14159: Fix the len() of weak containers (WeakSet, WeakKeyDictionary, WeakValueDictionary) to return a better approximation when some objects are dead or dying.
Moreover, the implementation is now O(1) rather than O(n).
Thanks to Yury Selivanov for reporting.
diff --git a/Lib/weakref.py b/Lib/weakref.py
index 468f8f1..fcb6b74 100644
--- a/Lib/weakref.py
+++ b/Lib/weakref.py
@@ -78,7 +78,7 @@
del self.data[key]
def __len__(self):
- return sum(wr() is not None for wr in self.data.values())
+ return len(self.data) - len(self._pending_removals)
def __contains__(self, key):
try:
@@ -290,7 +290,7 @@
return self.data[ref(key)]
def __len__(self):
- return len(self.data)
+ return len(self.data) - len(self._pending_removals)
def __repr__(self):
return "<WeakKeyDictionary at %s>" % id(self)