Patches item #1692335, was opened at 2007-04-01 13:46 Message generated for change (Comment added) made by gbrandl You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=305470&aid=1692335&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: Core (C code) Group: Python 2.5 Status: Open Resolution: None Priority: 5 Private: No Submitted By: Ziga Seilnacht (zseil) Assigned to: Nobody/Anonymous (nobody) Summary: Move initial args assignment to BaseException.__new__ Initial Comment: Pickling exceptions fails when an Exception class requires an argument in the constructor, but doesn't call its base class' constructor. See this mail for details: http://mail.python.org/pipermail/python-dev/2007-April/072416.html This patch simply moves initial args assignment to BaseException.__new__. This should fix most of the problems, because it is very unlikely that an exception overwrites the __new__ method; exceptions used to be old style classes, which don't support the __new__ special method. The args attribute is still overwritten in all the __init__ methods, so there shouldn't be any backward compatibility problems. ---------------------------------------------------------------------- >Comment By: Georg Brandl (gbrandl) Date: 2007-08-11 09:06 Message: Logged In: YES user_id=849994 Originator: NO Attaching a new patch that fixes the class D(Exception): def __init__(self, foo): self.foo = foo Exception.__init__(self) scenario by keeping the original args to __new__ as an exception attribute. File Added: exception-pickling.diff ---------------------------------------------------------------------- Comment By: Eric Huss (ehuss) Date: 2007-06-27 18:45 Message: Logged In: YES user_id=393416 Originator: NO Added patch #1744398 as an alternate solution. ---------------------------------------------------------------------- Comment By: Eric Huss (ehuss) Date: 2007-06-15 00:34 Message: Logged In: YES user_id=393416 Originator: NO I have stumbled across another scenario where unpickling fails. If your exception takes arguments, but you call Exception.__init__ with a different number of arguments, it will fail. As in: class D(Exception): def __init__(self, foo): self.foo = foo Exception.__init__(self) ---------------------------------------------------------------------- Comment By: Ziga Seilnacht (zseil) Date: 2007-04-01 21:50 Message: Logged In: YES user_id=1326842 Originator: YES I'm attaching a test that Eric Huss sent in private mail. The test fails, because old exception pickles don't have args for the reconstructor, but their __init__() gets called anyway because they are new style classes now. The problem is in cPickle.InstanceNew() and pickle.Unpickler._instantiate(). Those methods behave differently depending on the type of the object instantiated; they avoid the __init__() call when type is an old style class. There is nothing that can be done in the exception classes to fix this issue; the fix would need to be in the pickle and cPickle module. File Added: test_exception_pickle.py ---------------------------------------------------------------------- Comment By: Ziga Seilnacht (zseil) Date: 2007-04-01 13:47 Message: Logged In: YES user_id=1326842 Originator: YES File Added: exc_args_25.diff ---------------------------------------------------------------------- You can respond by visiting: https://sourceforge.net/tracker/?func=detail&atid=305470&aid=1692335&group_id=5470 _______________________________________________ Patches mailing list Patches@python.org http://mail.python.org/mailman/listinfo/patches
