cPickle problems

Jeff Poole korvus at gmail.com
Fri Nov 17 03:21:51 CET 2006

Good idea.  Well, I did that, and I found out that the object causing
problems is a ParseResults object (a class from PyParsing) and that the
__getstate__ member is in fact an empty string ('').  I'm not sure
where this leaves me...  The PyParsing code clearly never creates such
a member and my code never creates it.  In fact, searching all the code
involved (not including what is in /usr/lib/python2.4 ), shows no use
of __getstate__ at all (or even the string "getstate").

Ok, I figured it out.  ParseResults has the following member:

    def __getattr__( self, name ):
        if name not in self.__slots__:
            if self.__tokdict.has_key( name ):
                if name not in self.__accumNames:
                    return self.__tokdict[name][-1][0]
                    return ParseResults([ v[0] for v in
self.__tokdict[name] ])
                return ""
        return None

So when something tries to retrieve .__getstate__, it returns an empty
string.  If I tell it to raise an AttributeException instead, then I
get this message:

TypeError: a class that defines __slots__ without defining __getstate__
cannot be pickled

I think I need to talk to the author of PyParsing about this one...
Thanks for your help!


> Someway, self.__getstate__ is a string, not a method...
> Since it fails inside a python module, you could print some debug
> information to see what happens, like repr(self), type(self), repr(getstate)...
> --
> Gabriel Genellina
> Softlab SRL
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