函数装饰器----常用

1.统计运行时间

import time
def cal_time(func):
    def wrapper(*args, **kwargs):
        t1 = time.time()
        x = func(*args, **kwargs)
        t2 = time.time()
        print("%s running time %s secs."%(func.__name__, t2-t1))
        return x
    return wrapper