python-闭包和装饰器

https://www.zhihu.com/question/25950466/answer/31731502

import time

def addspam(timeout=-1):

    def _addspam(fn):
        sp = ['*', '#', '%']

        def __addspam(*args):
            print fn.__name__
            i = 0
            st = time.time()
            while True:
                if time.time() - st >= timeout:
                    if i >= len(sp):
                        i = 0
                    print sp[i] * 5
                    i += 1
                    st = time.time()
            return fn(*args)
        return __addspam
    return _addspam

@addspam(timeout=2)
def useful(a, b):
    print a**2 + b ** 2

if __name__ == "__main__":
    useful(2, 3)

代码可视化： http://pythontutor.com/

利用装饰器的一个git项目：