James Stroud wrote:
Hello All,
I subclassed dict and overrode __setitem__. When instances are
unpickled, the __setstate__ is not called before the keys are assigned
via __setitem__ in the unpickling protocol.
I googled a bit and found that this a bug filed in 2003:
http://bugs.python.org/issue826897
It is still "open" with "normal" priority.
Here is the ugly "fix" I'm basically going to have to live with, it seems:
class DictPlus(dict):
def __init__(self, *args, **kwargs):
self.extra_thing = ExtraThingClass()
dict.__init__(self, *args, **kwargs)
def __setitem__(self, k, v):
try:
do_something_with(self.extra_thing, k, v)
except AttributeError:
self.extra_thing = ExtraThingClass()
do_something_with(self.extra_thing, k, v)
dict.__setitem__(self, k, v)
def __setstate__(self, adict):
pass
This violates this:
Beautiful is better than ugly.
I can't imagine this bug has survived but I also can't imagine any
better way to do this without specifying a different protocol, which
would probably break other pickling I'm doing. I don't feel like finding
out right now.
Maybe repeal pep 307 ;o)
James
--
James Stroud
UCLA-DOE Institute for Genomics and Proteomics
Box 951570
Los Angeles, CA 90095
http://www.jamesstroud.com
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