python学习手册中的python多态示例代码

class handGun():
    def __init__(self):
        pass
    def fire(self):
        print 'handGun fire'

class carbine():
    def __init__(self):
        pass
    def fire(self):
        print 'carbine fire'

import handGun
import carbine
class gunFactory():
    def __init__(self,gun_type):
        self.gun_type = gun_type
    def produce(self):
        if handGun == self.gun_type:
            return handGun.handGun()
        else:
            return carbine.carbine()

fa = gunFactory(handGun)
gun = fa.produce()

/*只要是枪，就认为它具有开火的功能，如果没有开火的功能，程序运行中就报错*/
gun.fire()