Python-сообщество

#--------------------------------------
class A(object):
    def __init__( self, x, y ):
        self.x = x
        self.y = y
        pass
#-------    
    def __add__( self, arg ):
       tmp1 = self.x + arg.x
       tmp2 = self.y + arg.y
       return tmpA( A( tmp1, tmp2 ) )
    
    def change( self, x, y ):
        self.x = x
        self.y = y
        pass
    pass
#------------------------------------------
class tmpA( object ):
    def __init__( self, theA ):
        self.A = theA
        pass
#-------   
    def _print ( self ):
        print "    x =", self.A.x
        print "    y =", self.A.y
        pass
#-------
    def __call__( self ):
        return self.A
#-------   
    def __coerce__( self, *args ):
        return None

#-------
    def __getattr__( self, *args ):
        name = args[ 0 ]
        try:
            attr = None
            exec "attr = self.__call__().%s" % name
            return attr
        except :
            raise AttributeError

#--------------------------------------
class B( object ):
    def __init__( self, x, y):
        self.x = x
        self.y = y
        pass
#-------------------------------------
a=A( 1,2 )
b=B( 3,4 )
tmp_a = a + b  #все в порядке
tmp_a.change( 0, 0 ) # все в порядке!!!
v = tmp_a + b  #TypeError: "unsupported operand type(s) for +: 'tmpA' and 'B'"