At Friday 20/10/2006 18:33, Chris wrote:
Why can pickle serialize references to functions, but not methods?
Because all references must be globally accessible.
Pickling a function serializes the function name, but pickling a
staticmethod, classmethod, or instancemethod generates an error. In
these cases, pickle knows the instance or class, and the method, so
what's the problem? Pickle doesn't serialize code objects, so why can't
it serialize the name as it does for functions? Is this one of those
features that's feasible, but not useful, so no one's ever gotten
around to implementing it?
Well, it's not so common to take a method from one class and glue it
into an *instance* of another class...
(Note that if you copy&paste a method from one *class* into another
*class*, pickle works OK, as long as in the unpickling environment
you rebuild your classes the same way)
For static methods there is no way you can retrieve a globally usable
name (like 'Functions.somefunc' in your example) - at least I don't
know how to do it, they appear to have lost any reference to the
defining class.
For class methods you can build such reference using im_self and
im_func.func_name
For instance methods use im_class and im_func.func_name
Then define your own __getstate__ and __setstate__.
--
Gabriel Genellina
Softlab SRL
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