From bbe2f60b3c19ecaa02ca07be14474eaacfcb59a0 Mon Sep 17 00:00:00 2001
From: Antoine Pitrou <solipsis@pitrou.net>
Date: Thu, 1 Mar 2012 16:26:35 +0100
Subject: 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.

---
 Lib/weakref.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

(limited to 'Lib/weakref.py')

diff --git a/Lib/weakref.py b/Lib/weakref.py
index 468f8f1029..fcb6b74d1b 100644
--- a/Lib/weakref.py
+++ b/Lib/weakref.py
@@ -78,7 +78,7 @@ class WeakValueDictionary(collections.MutableMapping):
         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 @@ class WeakKeyDictionary(collections.MutableMapping):
         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)
-- 
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