标签：等价 int host strong class starting 属性 获取 反射
反射的意义：通过字符串获取一个类的方法的内存地址，并调用该方法。
格式：if hasattr(self, ‘anAttr‘)
func = getattr(self, ‘anAttr‘) #获取内存地址
func() #调用该方法，等价于anAttr()
setattr(x, ‘y‘, v)
delattr(x, ‘y‘)
看下面这个例子
版本一：效率低下，若类WebServer中的方法多个上百，那么主函数中的if语句就要判断上百次。
import sys class WebServer(object): def __init__(self,host,port): self.host = host self.port = port def start(self): print("Server is starting...") def stop(self): print("Server is stopping...") def restart(self): self.stop() self.start() if __name__ == "__main__": server = WebServer(‘localhost‘ ,333) print(sys.argv[1]) #执行脚本时的第一个参数 if sys.argv[1] == ‘start‘: server.start() elif sys.argv[1] == ‘stop‘: server.stop() elif sys.argv[1] == ‘restart‘: server.restart()
版本二：引入字典的思想，不过还是存在代码重用的现象，还可以继续改进
import sys class WebServer(object): def __init__(self,host,port): self.host = host self.port = port def start(self): print("Server is starting...") def stop(self): print("Server is stopping...") def restart(self): self.stop() self.start() if __name__ == "__main__": server = WebServer(‘localhost‘ ,333) print(sys.argv[1]) cmd_dic = { ‘start‘: server.start, ‘stop‘: server.stop, } if sys.argv[1] in cmd_dic: cmd_dic[sys.argv[1]]()
版本三：引入反射
import sys class WebServer(object): def __init__(self,host,port): self.host = host self.port = port def start(self): print("Server is starting...") def stop(self): print("Server is stopping...") def restart(self): self.stop() self.start() if __name__ == "__main__": server = WebServer(‘localhost‘ ,333) print(sys.argv[1]) if hasattr(server, sys.argv[1]): func = getattr(server, sys.argv[1]) #获取server.start 的内存地址 func() #等价于server.start()
反射方法之setattr
import sys class WebServer(object): def __init__(self,host,port): self.host = host self.port = port def start(self): print("Server is starting...") def stop(self): print("Server is stopping...") def restart(self): self.stop() self.start() def testRun(ins, name): #该方法并不是类的方法哦，但是可以用set绑定到实例中去 print("running....",name,ins.host) #ins相当于self if __name__ == "__main__": server = WebServer(‘localhost‘ ,333) server1 = WebServer(‘localhost1‘, 666) print(sys.argv[1]) #setattr(x, ‘y‘, v) is equivalent to x.y = v setattr(server, ‘run‘, testRun) #给实例server绑定了testRun,重命名为run server.run(server, ‘wuwen‘) #将server传给ins（实例） server1.run(server, ‘wuwen‘)
反射方法之delattr
class WebServer(object): def __init__(self,host,port): self.host = host self.port = port def start(self): print("Server is starting...") def stop(self): print("Server is stopping...") def restart(self): self.stop() self.start() if __name__ == "__main__": server = WebServer(‘localhost‘ ,333) delattr(server, ‘stop‘) #错误写法，实例无法参数类中的方法 print(server.host) delattr(server, ‘host‘) #删除参数实例中的属性host print(server.host) delattr(WebServer, ‘restart‘) #删除参数类中的restart方法 print(server.restart())
标签：等价 int host strong class starting 属性 获取 反射
原文地址：http://www.cnblogs.com/wuwen19940508/p/6716617.html
