Bugs item #750328, was opened at 2003-06-06 23:13 Message generated for change (Comment added) made by birkenfeld You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=750328&group_id=5470
Please note that this message will contain a full copy of the comment thread, including the initial issue submission, for this request, not just the latest update. Category: Type/class unification Group: Python 2.2.3 Status: Open Resolution: None Priority: 5 Submitted By: Phillip J. Eby (pje) Assigned to: Nobody/Anonymous (nobody) Summary: Pickle fails to restore new-style class instance in a cycle Initial Comment: Here is code to demonstrate the problem. All asserts succeed except the last, showing that pickle and cPickle both handle a "classic" cycle correctly, but only cPickle handles new-style cycles correctly. It would appear that the problem is that the pure-Python pickle isn't putting the object into its 'memo' until *after* the object's state has been pickled. Thus, the identity is not preserved on unpickling. This may be true for other object types that use __reduce__, but I have not verified this. import pickle, cPickle class X: pass x = X() x.x = x x2 = cPickle.loads(cPickle.dumps(x)) assert x2.x is x2 x2 = pickle.loads(pickle.dumps(x)) assert x2.x is x2 class Y(object): pass y = Y() y.y = y y2 = cPickle.loads(cPickle.dumps(y)) assert y2.y is y2 # this fails y2 = pickle.loads(pickle.dumps(y)) assert y2.y is y2 ---------------------------------------------------------------------- >Comment By: Reinhold Birkenfeld (birkenfeld) Date: 2005-09-01 00:04 Message: Logged In: YES user_id=1188172 Runs find in 2.5cvs too. ---------------------------------------------------------------------- Comment By: Reinhold Birkenfeld (birkenfeld) Date: 2005-05-31 13:34 Message: Logged In: YES user_id=1188172 Runs fine in Py2.4.1 too, so should it be considered fixed? ---------------------------------------------------------------------- Comment By: Raymond Hettinger (rhettinger) Date: 2003-07-01 05:00 Message: Logged In: YES user_id=80475 Another datapoint: This above script runs fine in Py2.3b2. ---------------------------------------------------------------------- Comment By: Steven Taschuk (staschuk) Date: 2003-06-08 22:23 Message: Logged In: YES user_id=666873 Compare bug 702858, which observes the same behaviour for copy.deepcopy. The common parts of pickle and copy really ought to be merged. ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=105470&aid=750328&group_id=5470 _______________________________________________ Python-bugs-list mailing list Unsubscribe: http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
