please give me a simple example about__setstate__ and __getstate__,thanks

Question

i don't know what__setstate__ __getstate__ does ,so help me use a simple example,thanks

__setstate__ __getstate__

Answer 1

These methods are used for controlling how objects are pickled and unpickled by the pickle module. This is usually handled automatically, so unless you need to override how a class is pickled or unpickled you shouldn't need to worry about it.

Answer 2

Here's a very simple example that should supplement the pickle docs.

class Foo(object):
def __init__(self, val=2):
        self.val = val
def __getstate__(self):
    print 'im being pickled'
    self.val *= 2
    return self.__dict__
def __setstate__(self, d):
    print 'im being unpickled with these values', d
    self.__dict__ = d
    self.val *= 3

import pickle
f = Foo()
f_string = pickle.dumps(f)
f_new = pickle.loads(s)