From 6b96ecb0ab8d06b7c11d1b82baebc47452a7b13e Mon Sep 17 00:00:00 2001
From: Raymond Hettinger <python@rcn.com>
Date: Sat, 3 Apr 2010 03:14:28 +0000
Subject: Improve clear() method.  Keeps key/value refcnts >= 1 until final
 dict.clear() so that decrefs to zero won't trigger arbitrary code .  Also
 runs a bit faster.

---
 Lib/collections.py | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/Lib/collections.py b/Lib/collections.py
index 1f1f510..79f6696 100644
--- a/Lib/collections.py
+++ b/Lib/collections.py
@@ -107,8 +107,14 @@ class OrderedDict(dict, MutableMapping):
 
     def clear(self):
         'od.clear() -> None.  Remove all items from od.'
-        for k in dict.keys(self):
-            del self[k]
+        try:
+            for node in self.__map.itervalues():
+                del node[:]
+            self.__root[:] = [self.__root, self.__root, None]
+            self.__map.clear()
+        except AttributeError:
+            pass
+        dict.clear(self)
 
     setdefault = MutableMapping.setdefault
     update = MutableMapping.update
-- 
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