python—装饰器

定义：本质是函数，（装饰其他函数）就是为其他函数添加附加功能

原则：1.不能修改被装饰的函数的源代码

 2.不能修改被装饰的函数的调用方式

 

实现装饰器知识储备：

1.函数即“变量”

2.高阶函数

3.嵌套函数

 

高阶函数+嵌套函数=装饰器

---

 

初级版本:

用pycharm下断点 可以看出函数的运行过程！

机器运行过程

1.定义了 timer,test1,test2 3个函数

2.timer(test1) 执行函数timer(func),因为函数没有调用就往下走到了deco函数也没调用直接返回

3.test1 = timer(test1) 接上面的返回给了test1

4.test1() 调用deco函数体 先执行到 start_time=time.time() 

然后执行func() 进入test1函数体 睡眠1秒 先后输出 in the test1

然后在执行 stop_time = time.time() -->print("the func run time is %s" %(stop_time-start_time))

# -*- coding:utf-8 -*-
import time
def timer(func): #timer(test1)  func=test1
    def deco():
        start_time=time.time()
        func()   #run test1()
        stop_time = time.time()
        print("the func run time  is %s" %(stop_time-start_time))
    return deco
def test1():
    time.sleep(1)
    print('in the test1')
def test2():
    time.sleep(1)
    print('in the test2')
test1 =timer(test1)
test1()

---

进阶版:

import time
def timer(func):
    def deco():
        start_time=time.time()
        func()
        stop_time = time.time()
        print("the func run time  is %s" %(stop_time-start_time))
    return deco
@timer # 这个就相当于上面的test1 = timer(test1) 
def test1():
    time.sleep(1)
    print('in the test1')
@timer  # test2 = timer(test2)
def test2():
    time.sleep(1)
    print('in the test2')
test1()
test2()

---

高级版：

import time
def timer(func): #timer(test1)  func=test1
    def deco(*args,**kwargs):
        start_time=time.time()
        func(*args,**kwargs)   #run test1()
        stop_time = time.time()
        print("the func run time  is %s" %(stop_time-start_time))
    return deco
@timer  #test1=timer(test1)
def test1():
    time.sleep(1)
    print('in the test1')
@timer # test2 = timer(test2)  = deco  test2(name) =deco(name)
def test2(name,age):
    print("test2:",name,age)
test1()
test2("alex",22)

---

终极版：

import time
user,passwd = 'alex','abc123'
def auth(auth_type):
    print("auth func:",auth_type)
    def outer_wrapper(func):
        def wrapper(*args, **kwargs):
            print("wrapper func args:", *args, **kwargs)
            if auth_type == "local":
                username = input("Username:").strip()
                password = input("Password:").strip()
                if user == username and passwd == password:
                    print("\033[32;1mUser has passed authentication\033[0m")
                    res = func(*args, **kwargs)  # from home
                    print("---after authenticaion ")
                    return res
                else:
                    exit("\033[31;1mInvalid username or password\033[0m")
            elif auth_type == "ldap":
                print("搞毛线ldap,不会。。。。")
        return wrapper
    return outer_wrapper
def index():
    print("welcome to index page")

@auth(auth_type="local") # home = wrapper()
def home():
    print("welcome to home  page")
    return "from home"
@auth(auth_type="ldap")
def bbs():
    print("welcome to bbs  page")
index()
print(home()) #wrapper()
bbs()

用pycharm下断点慢慢看