On 02:06 pm, gary...@me.com wrote:
When you define a class in a script, and then pickle instances of that
class in the same script and store them to disk, you can't load that
pickle in another script. At least not the straightforward way
[pickle.load(file('somefile.pickle'))]. If you try it, you get an
AttributeError during the unpickling operation.
There is no problem, of course, if the class is defined in a module
which is imported by the pickling script.
pickle.load(file('somefile.pickle')) then works.
Rather than provide specific examples here, there's a blog post from
2005 that discusses this issue in depth and presents the problem very
well: http://stefaanlippens.net/pickleproblem. (I tested in Python 2.6
yesterday and the same issue persists.)
Questions:
1) Does this have to be the case, or is it a design problem with
pickles that should be remedied?
2) Is there an easier way around it than moving the class definition to
a separate module? The blog post I point to above suggests putting
"__module__ = os.path.splitext(os.path.basename(__file__))[0]" into the
class definiton, but that's not working in my testing because when I do
that, the pickling operation fails. Is there something else that can be
done?
I described another solution here:
http://jcalderone.livejournal.com/45604.html
Jean-Paul
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