装饰器本质

#装饰器：本质是函数，功能：装饰其他函数，就是为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.不能修改被装饰函数的调用方式不能修改

#实现装饰器知识储备
#1.函数及“变量”
#2.高阶函数
#3.嵌套函数
#最终：高阶函数 + 嵌套函数 =》装饰器
import time
def timmer(func):  #是一个函数  把test1的内存地址给了func
    def warpper(*args,**kwargs):
        start_time=time.time()
        func()   #这里就是执行test1
        stop_time=time.time()
        print("the func run time is %s" %(stop_time-start_time))
    return warpper

@timmer #等于 test1=timer(test1)

def test1():
    time.sleep(3)
    print("in the test1")

#test1=timer(test1)
test1()

实例2：

import time
def timmer(func):  #是一个函数
    def warpper(*args,**kwargs):
        start_time=time.time()
        func(*args,**kwargs)
        stop_time=time.time()
        print("the func run time is %s" %(stop_time-start_time))
    return warpper

@timmer #test1=timer(test1)
def test1():
    time.sleep(1)
    print("in the test1")
@timmer #test1=timer(test1)
def test2(name):
    print("name:",name)

test1()
test2("alex")

实例3：

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()