Issue 7835: Shelve's __del__ method calls its close method, and its

close method refers to an identifier in the global module namespace.
This means that when __del__ is called during interpreter shutdown (if,
for example, the calling program still has a pointer to the shelf),
sometimes that global identifier would wind up being None, causing
mysterious 'ignored' exceptions.  This patch checks for the possible None
value first before using the global, thus avoiding the error messages.

diff --git a/Lib/shelve.py b/Lib/shelve.py
index fb41c844e4fa51760bf087756d02bbf580c12e48..8055f42e2291fb4ffa4fac27ab7feb566d0ce4a4 100644 (file)
--- a/Lib/shelve.py
+++ b/Lib/shelve.py
@@ -145,7 +145,11 @@ class Shelf(UserDict.DictMixin):
             self.dict.close()
         except AttributeError:
             pass
-        self.dict = _ClosedDict()
+        # _ClosedDict can be None when close is called from __del__ during shutdown
+        if _ClosedDict is None:
+            self.dict = None
+        else:
+            self.dict = _ClosedDict()
 
     def __del__(self):
         if not hasattr(self, 'writeback'):

diff --git a/Misc/NEWS b/Misc/NEWS
index 2eccbabe9e4632b5b2c0dc15f42078c03fceb9f1..0d86fe75311c313df5a2a345e2963394aeb1a300 100644 (file)
--- a/Misc/NEWS
+++ b/Misc/NEWS
@@ -94,6 +94,9 @@ Core and Builtins
 Library
 -------
 
+- Issue #7835: shelve should no longer produce mysterious warnings during
+  interpreter shutdown.
+
 - Issue #2746: Don't escape ampersands and angle brackets ("&", "<", ">")
   in XML processing instructions and comments.  These raw characters are
   allowed by the XML specification, and are necessary when outputting e.g.