类的三大装饰器之property

# property：

import math
class Circle(object):
    def __init__(self, r):
        self.r = r

    @property  # 把一个方法伪装成一个属性，调用这个方法时不需要加括号就直接得到返回值
    def area(self):
        return math.pi * self.r**2

c = Circle(5)
print(f'半径：{c.r}, 面积：{c.area}')


import time
class Person(object):
    def __init__(self, name, birth):
        self.name = name
        self.birth = birth

    @property
    def age(self):  # 所以装饰的这个方法不能有参数
        return time.localtime().tm_year - self.birth

TB = Person('太白', 1998)
print(TB.age)


# property的第二个应用场景：和私有属性合作的
class User(object):
    def __init__(self, user, pwd):
        self.user = user
        self.__pwd = pwd

    @property
    def pwd(self):
        return self.__pwd

alex = User('alex', 123)
print(alex.pwd)


# property进阶：
class Goods(object):
    discount = 0.8

    def __init__(self, name, oringin_price):
        self.name = name
        self.__price = oringin_price

    @property
    def price(self):
        return self.__price * self.discount

    @price.setter
    def price(self, new_price):
        print('调用我了---')
        if isinstance(new_price, int):
            self.__price = new_price

    @price.deleter
    def price(self):
        print('执行我了')
        del self.__price


apple = Goods('apple', 5)
print(apple.price) # 查看被@property装饰的price函数

apple.price = 10  # 调用的是被setter装饰的price
print(apple.price)

# del apple.price  # 调用的是被deleter装饰的price，而这里只是调用方法，要在方法内部执行删除
# print(apple.price)