class A( object ):
    def __init__( self ):
        self.__setstate__( {} )

    def __setstate__( self, d ):
        self.a = 1
        self.__dict__.update( d )


    def __getstate__( self ):
        d = self.__dict__.copy()
        d.pop( 'a' )
        return d

a = A()
print a.__dict__

a.__setstate__( a.__getstate__() )
print a.__dict__

from copy import  deepcopy
print deepcopy( a ).__dict__