python计算程序执行时间的装饰器使用

1、经常被问程序执行了多久，每个函数都去写很麻烦，所以打算写个装饰器自动计算程序执行时间；推荐文档，大多数基础题都有：  https://python3-cookbook.readthedocs.io/zh_CN/latest/ 

import  time

def  clock(func):
    def clocked(*args, **kwargs):
        start = time.time()
        result = func(*args, **kwargs)
        end = time.time()
        print(func.__name__, end - start)
        return  result
    return clocked

@clock
def test():
    print("excute...")
    time.sleep(5)
    
test()
执行结果：

"D:Program Filespython3.6.7python.exe" D:/pythonWorkspace/untitled4/22.py
excute...
test 5.000607967376709

Process finished with exit code 0

2、装饰器错误使用方法

import datetime
import  time

def  clock(func):
    start = datetime.datetime.now()
    print(start)
    def clocked(*args, **kwargs):
        func(*args, **kwargs)
    end = datetime.datetime.now()
    total = (end - start).total_seconds()
    print(end)
    print("执行%s耗时：%d" %(func.__name__, total))
    return clocked

@clock
def test():
    print("excute...")
    time.sleep(5)

test()
错误的执行结果：

"D:Program Filespython3.6.7python.exe" D:/pythonWorkspace/untitled4/55.py
2019-08-19 10:24:29.904106
2019-08-19 10:24:29.904106
执行test耗时：0
excute...

Process finished with exit code 0

-------------------------------------------------------------------------------------

适用于例如：

　　- 验证用户类型

def user_auth(user_group):
    def wrapper(func):
        def inner(*args, **kwargs):
            if user_group == 'SVIP':
                print('Dear SVIP')
                res = func(*args, **kwargs)
                return res

            elif user_group == 'General':
                res = func(*args, **kwargs)
                return res

            else:
                print('Please login first!')
                login()

        return inner

    return wrapper


@user_auth(user_group='SVIP')
def welcome():
    print('Welcome to the index')