[Python知识库]PY装饰器

import random
import time


def download(filename):
    print(f'开始下载{filename}')
    time.sleep(random.randint(2, 6))
    print(f'{filename}下载完成')

def upload(filename):
    print(f'开始上传{filename}')
    time.sleep(random.randint(4, 8))
    print(f'{filename}上传完成')

start = time.time()
#download('MySql从删库到跑路.avi')
end = time.time()
print(f'花费时间:{end - start:.3f}秒')
start = time.time()
#upload('Python从入门到住院.pdf')
end = time.time()
print(f'花费时间：{end - start:.3f}秒')

#重复的代码是万恶之源  装饰器
# 定义装饰器函数，它的参数是被装饰的函数或类
def record_time(func):

    #定义一个带装饰功能（记录被装饰函数的执行时间）的函数
    #因为不知道被装饰的函数有怎样的参数所以使用*args 和 **kwargs接收所有参数
    #在Python中函数可以嵌套的定义（函数中可以再定义函数)
    def wrapper(*args, **kwargs):
        start = time.time()
        result = func(*args, **kwargs)
        end = time.time()
        print(f'{func.__name__}执行时间:{end - start:.3f}秒')
        return result

    return wrapper

download = record_time(download)
download('JAVA教学.avi')

#语法糖 @装饰器函数

@record_time
def download(filename):
    print(f'开始下载{filename}')
    time.sleep(random.randint(1, 3))
    print(f'{filename}下载完成')

@record_time
def upload(filename):
    print(f'开始上传{filename}')
    time.sleep(random.randint(1, 3))
    print(f'{filename}上传完成')

download('Mysql从删库到跑路.avi')
upload('Py从入门到入土.pdf')