装饰器

Posted 2021-01-31 jt925

闭包：

如：

def func1():
    a = 10
    def func2():
        print(a)
    return func2
f = func1()  # 此时得到func2,func1应该释放对应的内存
f()  # 此时相当于运行 func2(),但由于func1已经执行完毕，按理说变量a应该不存在了，此时执行func2
因该报错才是，但事实是f()调用正常，这个现象叫做闭包。
总结：一个函数包含子函数，并且子函数调用了父函数下的变量，父函数的返回值为子函数的函数名，满足这种条件的函数叫做闭包

 

装饰器：

软件开发中的一个原则“开放-封闭”原则，简单来说，它规定已经实现的功能代码不允许被修改，但可以被扩展，即：

• 封闭：已实现的功能代码块不应该被修改
• 开放：对现有功能的扩展开放

函数未带参数：

user_status = False
def login(func):
    def inner():
        _username = "jiangsq"  # 假装这是DB里存的用户信息
        _password = "js123"  # 假装这是DB里存的用户信息
        global user_status
        if user_status == False:
            username = input("user:")
            password = input("pasword:")
            if username == _username and password == _password:
                print("welcome login......")
                user_status = True
            else:
                print("weong username or password!")
        if user_status:
            return func()
    return inner

def home():
    print(‘首页‘)
def america():
    print(‘欧美专区‘)
@login
def japan():
    print(‘日韩专区‘)

函数带参数：

user_status = False
def login(func):
    def inner(arg):
        _username = "jiangsq"  # 假装这是DB里存的用户信息
        _password = "js123"  # 假装这是DB里存的用户信息
        global user_status
        if user_status == False:
            username = input("user:")
            password = input("pasword:")
            if username == _username and password == _password:
                print("welcome login......")
                user_status = True
            else:
                print("weong username or password!")
        if user_status:
            return func(arg)
    return inner

def home():
    print(‘首页‘)
def america():
    print(‘欧美专区‘)
@login
def japan(arg):
    print(‘日韩专区‘)
    print(arg)

japan(‘哈哈哈‘)

带参函数第二版：

user_status = False
def login(func):
    def inner(*args,**kwargs):
        _username = "jiangsq"  # 假装这是DB里存的用户信息
        _password = "js123"  # 假装这是DB里存的用户信息
        global user_status
        if user_status == False:
            username = input("user:")
            password = input("pasword:")
            if username == _username and password == _password:
                print("welcome login......")
                user_status = True
            else:
                print("weong username or password!")
        if user_status:
            return func(*args,**kwargs)
    return inner

def home():
    print(‘首页‘)
@login
def america():
    print(‘欧美专区‘)
@login
def japan(arg):
    print(‘日韩专区‘)
    print(arg)

japan(‘哈哈哈‘)
america()

带参装饰器：

user_status = False
def login(auth_type):
    def outer(func):
        def inner(*args,**kwargs):
            _username = "jiangsq"  # 假装这是DB里存的用户信息
            _password = "js123"  # 假装这是DB里存的用户信息
            global user_status
            if user_status == False:
                username = input("user:")
                password = input("pasword:")
                if username == _username and password == _password:
                    print("welcome login......")
                    user_status = True
                else:
                    print("weong username or password!")
            if user_status:
                return func(*args,**kwargs)
        return inner
    return outer

def home():
    print(‘首页‘)
@login(‘aaa‘)  # 过程 login(‘eeee‘) =》 outer(japan) =》 inner()
def america():
    print(‘欧美专区‘)
@login(‘eeee‘)  # 过程 login(‘eeee‘) =》 outer(japan) =》 inner(arg)
def japan(arg):
    print(‘日韩专区‘)
    print(arg)

# japan(‘哈哈哈‘)
america()
# xx = login(‘qq‘) # outer
# japan = xx(japan)
# japan(‘哈哈哈‘)

 

装饰类的装饰器：

一、
# 描述符判断被描述的对象输入的类型是不是想要的类型
class miaoshufu:
    def __init__(self, key, expected_type):
        self.key = key
        self.type = expected_type

    def __set__(self, instance, value):
        if type(value) is self.type:
            instance.__dict__[self.key] = value
        else:
            print("%s传入的类型错误，应该是%s" %(value, self.type))

    def __get__(self, instance, owner):
        return instance.__dict__[self.key]

    def __delete__(self, instance):
        instance.__dict__.pop(self.key)


# 装饰器
def Typed(**kwargs):
    def zhuang(obj):
        for key,val in kwargs.items():
            setattr(obj, key, miaoshufu(key,val))
            # key = miaoshufu(str(key), val)
        return obj
    return zhuang


@Typed(name = str,age = int)   # 不然要写很多,这样减少了重复代码
class People:
    # name = miaoshufu(‘name‘, str)
    # age = miaoshufu(‘age‘, int)

    def __init__(self, name, age, salary, height):
        self.name = name
        self.age = age
        self.salary = salary
        self.height = height

p = People("wad", "awa", 10000, 173)

二、
def godme(fun):
    def __godme(cls, *args, **kwargs):
        print(‘before‘)
        fun(cls, *args, **kwargs)
        print(‘after‘)

    return __godme


@godme
class Person:
    def __new__(cls, *args, **kwargs):
        print(‘__new__‘)

Person(Person)