pickling class instances with __slots__

[Alex Martelli]

Alex <OurLab at gmail.com> wrote:
   ...
> I have a series of new classes with child-parent relationship and each
> has unique __slots__. They don't have __dict__ . I need to be able to
> pickle and unpickle them. As far as I could understand, I need to
> provide __getstate__  and  __setstate__ methods for each class. Is

Right.

> there a universally accepted code for each method? If so, what is it?
> If there is no standard, what works?

Lots of things work, the simplest is something like:

>>> class wehaveslots(object):
...   __slots__ = 'a', 'b', 'c'
...   def __getstate__(self): return self.a, self.b, self.c
...   def __setstate__(self, tup): self.a, self.b, self.c = tup

(plus presumably other methods, but those don't matter for pickle).


Alex