利用装饰器和上下文管理，函数执行前后增强

需求：

执行一个加函数后，统计一下耗时

装饰器

import time
import datetime

def logger(fn):
    def wraper(*args,**kwargs):
        start = start = datetime.datetime.now()
        ret = fn(*args,**kwargs)
        end = datetime.datetime.now()
        time_count = (end - start).total_seconds()
        print('耗时为{}'.format(time_count))
        return ret
    return wraper

@logger
def add(x,y):
    time.sleep(2)
    rt = x + y
    print('计算结果为{}'.format(rt))

add(3,4)

上下文管理

import time
import datetime

class Timeit:
    def __init__(self,x,y):
        self.x = x
        self.y = y
    def __enter__(self):
        self.start = datetime.datetime.now()
    def __exit__(self,exc_type,exc_val,exc_tb):
        self.end = datetime.datetime.now()
        self.time_count = (self.end - self.start).total_seconds()
        print('计算结果为{}'.format(self.rt))
        print('耗时为{}'.format(self.time_count))
    def add(self):
        time.sleep(2)
        self.rt = self.x + self.y
        return self.rt

    
a = Timeit(3,4)

with a as a1:
    a.add()