On Mon, 9 Dec 2002, Guido van Rossum wrote:
> It's a feature. When a class defines __slots__ and not __getstate__,
> it gets a bogus __getstate__ that always raises an exception. The
> assumption is that the base class __getstate__ doesn't know about the
> subclass slots and hence is unlikely to be able to retrieve them
> correctly.
>
> BTW, your code for accessing the slots by saying self.__slots__
> doesn't work in general: self.__slots__ returns the __slots__ variable
> of the most derived class only.
Here is my code for dealing with this "feature":
def __getstate__(self):
state = getattr(self, '__dict__', {}).copy()
for obj in type(self).mro():
for name in getattr(obj,'__slots__',()):
if hasattr(self, name):
state[name] = getattr(self, name)
return state
def __setstate__(self, state):
for key,value in state.items():
setattr(self, key, value)
I also have a meta-class that adds these methods for derived objects, since
the core decided to play it overly safe on this issue.
-Kevin
--
Kevin Jacobs
The OPAL Group - Enterprise Systems Architect
Voice: (216) 986-0710 x 19 E-mail: jacobs@theopalgroup.com
Fax: (216) 986-0714 WWW: http://www.theopalgroup.com
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