from math import pi

class Circle:

    def __init__(self,r):

        self.r = r

    @property

    def perimeter(self):

        return 2*pi*self.r

    @property

    def area(self):

        return self.r**2*pi

c1 = Circle(5)

print(c1.area)     # 圆的面积

print(c1.perimeter) # 圆的周长

property

class Stuff_price:

    def __init__(self,original_price,discount):

        self.__original_price=original_price

        self.__discount=discount

    @property

    def price(self):

        print('我执行了了价格')

        return self.__original_price*self.__discount

    @price.setter

    def price(self,new_discount):

        print('我执行了setter')

        self.__discount=new_discount

    @price.deleter

    def price(self):

        print('我执行了 delecte')

        # del self.__original_price

apple=Stuff_price(10,0.5)

print(apple.price)

apple.price=0.8

print(apple.price)

del apple.price

print(apple.price)

'''输出结果我执行了了价格

5.0

我执行了setter

我执行了了价格

8.0

我执行了 delecte

我执行了了价格

8.0

'''