装饰器

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.不能修改被装饰函数的源代码（新增功能）

2.不能修改被装饰的函数的调用方式

---》对于被修饰的函数，它感知不到装饰器的存在

import time
def timmer(func):
    def warpper(*args,**kwargs):
        start_time=time.time()
        func()     ????????????
        stop_time=time.time()
        print('the func run time is %s' %(stop_time-start_time))
    return warpper

@timmer
def test1():
    time.sleep(3)
    print('in the test1')

test1()

 实现装饰器的知识储备：

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

函数即‘变量’

def bar():
    print('in the bar')
def foo():
    print('in the foo')
    bar() 
foo()

def foo():
    print('in the foo')
    bar()
def bar():
    print('in the bar')
foo()
先声明，再调用时内存中已经存在 故二者结果相同
-------------------------------
# def foo():
#     print('in the foo')
#     bar()
#foo()
# def bar():
#     print('in the bar')

x

高阶函数：

1.把一个函数名当做实参传给另一个函数 

2.返回值中包含函数名

import time
def bar():
     time.sleep(3)
     print('in the bar')

def test1(func):
     start_time=time.time()
     func()    #run bar
     stop_time=time.time()
     print("the func run time is %s" %(stop_time-start_time))

 test1(bar)    --------》in the bar
                                 the func run time is %s
#在不改变源代码下为其添加功能  但调用方式改变 不是装饰器


import time
def bar():
    time.sleep(3)
    print('in the bar')
def test2(func):

     start_time=time.time()
     return   func()    #run bar   不走下面了
     stop_time=time.time()
     print("the func run time is %s" %(stop_time-start_time))

bar=test2(bar) 
bar() #run bar #不修改函数调用方式 但是没有加新功能

嵌套函数    def 内def 才叫嵌套

def foo():
    print('in the foo')
    def bar():  #局部变量  内部调用
        print('in the bar')
    bar()

foo()
  ---》

in the foo

in the bar

把高阶函数引入嵌套函数

import time
def deco(func):
    start_time=time.time()
    return func   #run test1()  以下不运行  引入嵌套函数
    stop_time = time.time()
    print("the func run time  is %s" %(stop_time-start_time))
 
def timer():
    def deco():
       pass

def test1():
    time.sleep(1)
    print('in the test1')


def test2():
    time.sleep(1)
    print('in the test2')

test1=deco(test1)
test1()
test2=deco(test2)
test2()

装饰器

装饰器1

import time
def timer(func): #timer(test1)  func=test1 把test1的内存地址传给func   返回的是deco的内存地址
    def deco():   
        start_time=time.time()
        func()   #里面正常做 不用return 了  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')

test1=timer(test1) #run deco  -->run test1  
test1()  #调用test1 执行deco

装饰器2

import time
def timer(func): #timer(test1)  func=test1 把test1的内存地址传给func   返回的是deco的内存地址
    def deco():   
        start_time=time.time()
        func()   #里面正常做 不用return 了  run test1
        stop_time = time.time()
        print("the func run time  is %s" %(stop_time-start_time))
    return deco

@timer  #相当于 test1=timer(test1) #run deco  -->run test1  
def test1():   
    time.sleep(1)
    print('in the test1')

@timer  #想要运行那个就写在哪个头部
def test2():
    time.sleep(1)
    print('in the test2')

test1()  #调用test1 执行deco
test2()

装饰器3  可以有无参数
import time
def timer(func): 
    def deco(*args,**kwargs):   
        start_time=time.time()
        func(*args,**kwargs)   #run test2()
        stop_time = time.time()
        print("the func run time  is %s" %(stop_time-start_time))
    return deco

@timer  
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)

一层装饰器

import time
user,passwd = 'alex','abc123'
def auth(auth_type):
      def wrapper(*args, **kwargs):
                username = input("Username:").strip()
                password = input("Password:").strip()
                if user == username and passwd == password:
                    print("33[32;1mUser has passed authentication33[0m")
                    func(*args, **kwargs) 
                else:
                    exit("33[31;1mInvalid username or password33[0m") 
        return wrapper

def index():
    print("welcome to index page")

@auth
def home():
    print("welcome to home  page")

@auth
def bbs():
    print("welcome to bbs  page")

index()
home()
bbs()

增加返回

import time
user,passwd = 'alex','abc123'
def auth(auth_type):
      def wrapper(*args, **kwargs):
                username = input("Username:").strip()
                password = input("Password:").strip()
                if user == username and passwd == password:
                    print("33[32;1mUser has passed authentication33[0m")
                    #run  home 没结果  可以res返回  
                     res = func(*args, **kwargs)  # from home
                    print("---after authenticaion ")
                    return res
                else:
                    exit("33[31;1mInvalid username or password33[0m") 
        return wrapper

def index():
    print("welcome to index page")

@auth
def home():
    print("welcome to home  page")
    return "from home"

@auth
def bbs():
    print("welcome to bbs  page")

index()
print(home()) #wrapper()
bbs()