只执行一次的装饰器

最近在看 参考手册，写的真心好，不过有些地方不够详细 p83 

event_handler={}
def eventhandler(event):
    def register(f):
        print(event)
        event_handler[event] = f
        return f
    return register

@eventhandler("button")
def handle_button(msg):
    print('this is %s button handle!~'%(msg))


handle_button('good')
handle_button('good')
handle_button('fuck')
print(event_handler)

猜猜结果是什么:

button
this is good button handle!~
this is good button handle!~
this is good button handle!~
this is fuck button handle!~
{'button': <function handle_button at 0x01705198>}

是不是出乎意料啊 

原来是这样的

# temp = eventhandler("button")
# handle_button = temp(handle_button) = register(handle_button) = handle_button

第一次执行的会变成这样，以后就是自身了， 发现他的伟大用处了吗，尽量想把，哈哈