I'd like to be able to pickle instancemethod objects mainly because I
want to be able to delay a call like ``foo(spam, badger)`` by dumping
``foo``, ``spam`` and ``badger`` to disk and loading them again later.
Sometimes the callable ``foo`` is actually a bound method, e.g.
``bar.baz``, but in such cases, pickle doesn't work by default because
it doesn't know how to pickle/unpickle instancemethod objects.
I was thinking of doing something like::
>>> def pickle_instancemethod(method):
... func_name = method.im_func.__name__
... cls = method.im_class
... obj = method.im_self
... return unpickle_instancemethod, (func_name, cls, obj)
...
>>> def unpickle_instancemethod(func_name, cls, obj):
... if obj is None:
... return getattr(cls, func_name)
... else:
... return getattr(obj, func_name)
...
>>> class C(object):
... def __init__(self, foo, bar):
... self.foo = foo
... self.bar = bar
... def baz(self):
... return self.foo, self.bar
...
>>> copy_reg.pickle(type(C.baz),
... pickle_instancemethod,
... unpickle_instancemethod)
This seems to basically do the right thing on the few simple things I've
tried::
>>> c = C(42, 'badger')
>>> new_c_baz = pickle.loads(pickle.dumps(c.baz))
>>> new_c_baz()
(42, 'badger')
>>> new_C_baz = pickle.loads(pickle.dumps(C.baz))
>>> new_C_baz(C('eki', 'fekang'))
('eki', 'fekang')
Does this approach seem sound? Am I going to run into some weird
problems doing it this way?
Thanks,
STeVe
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