[Python-Dev] Python 2.5.1c1 pickle problem

[Ralf W. Grosse-Kunstleve]

When pickling instances of an object derived from dict, the pickle in Python 2.5.1c1 calls the object's __getitem__() method. In contrast, earlier versions of Python incl. 2.5 don't call that method. Below is a minimal example with outputs. Is the difference in behavior an oversight or new feature? I couldn't find anything directly related in the release notes.
The difference in behavior breaks some of our code.
Thanks!
Ralf

class user(dict):

  def __getitem__(self, key):
    print "GETITEM", key

if (__name__ == "__main__"):
  import sys
  print sys.version
  u = user()
  u[1] = 2
  import pickle
  pickle.dumps(u)
  print "Done."


2.5.1c1 (r251c1:54692, Apr 11 2007, 16:15:52) 
[GCC 4.1.0 20060304 (Red Hat 4.1.0-3)]
GETITEM 1
Done.

2.5 (r25:51908, Apr 11 2007, 16:11:19) 
[GCC 4.1.0 20060304 (Red Hat 4.1.0-3)]
Done.

2.4.2 (#1, Feb 12 2006, 03:45:41) 
[GCC 4.1.0 20060210 (Red Hat 4.1.0-0.24)]
Done.

2.3.4 (#1, Oct 26 2004, 16:45:38) 
[GCC 3.4.2 20041017 (Red Hat 3.4.2-6.fc3)]
Done.

2.2.1 (#1, Aug 30 2002, 12:15:30) 
[GCC 3.2 20020822 (Red Hat Linux Rawhide 3.2-4)]
Done.





       
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