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
    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())

会用到私有属性这个概念的场景
    隐藏起一个属性，不想让类的外部调用
    我想保护这个属性，不想让属性随意被改变
    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


78.53981633974483
31.41592653589793

 

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('tim')
print(tiger.name)
tiger.name = '全班'
print(tiger.name)

timsb
全班sb