python基础（day26）

一、封装和@property

# class Room:
#     def __init__(self,name,length,width):
#         self.__name = name
#         self.__length = length
#         self.__width = width
#     def get_name(self):
#         return self.__name
#     def set_name(self,newName):
#         if type(newName) is str and newName.isdigit() == False:
#             self.__name = newName
#         else:
#             print('不合法的姓名')
#     def area(self):
#         return self.__length * self.__width
#
# jin = Room('金老板',2,1)
# print(jin.area())
# jin.set_name('2')
# print(jin.get_name())

# 假设父类的私有属性 能被 子类调用么
# class Foo:
#     __key = '123'       # _Foo__key
#
# class Son(Foo):
#     print(Foo.__key)     # _Son__key


# 会用到私有的这个概念de场景
#1.隐藏起一个属性 不想让类的外部调用
#2.我想保护这个属性，不想让属性随意被改变
#3.我想保护这个属性，不被子类继承

# property
# 内置装饰器函数 只在面向对象中使用
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

# class Person:
#     def __init__(self,name,high,weight):
#         self.name = name
#         self.high = high
#         self.weight = weight
#     @property
#     def bmi(self):
#         return self.weight / self.high**2

# jin = Person('金老板',1.6,90)
# jin.bmi = 18
# classmethod
# staticmethod

# class Person:
#     def __init__(self,name):
#         self.__name = name
#     @property
#     def name(self):
#         return self.__name + 'sb'
#     @name.setter
#     def name(self,new_name):
#         self.__name = new_name
#
# tiger = Person('泰哥')
# print(tiger.name)
# tiger.name = '全班'
# print(tiger.name)

# class Goods:
#     discount = 0.8
#     def __init__(self,name,price):
#         self.name = name
#         self.__price = price
#     @property
#     def price(self):
#         return self.__price * Goods.discount
# apple = Goods('苹果',5)
# print(apple.price)

# 属性 查看 修改 删除
# class Person:
#     def __init__(self,name):
#         self.__name = name
#         self.price = 20
#     @property
#     def name(self):
#         return self.__name
#     @name.deleter
#     def name(self):
#         del self.__name
#     @name.setter
#     def name(self,new_name):
#         self.__name = new_name
# brother2 = Person('二哥')
# del Person.price
# brother2.name = 'newName'
# brother2
# del brother2.name
# print(brother2.name)