Python数据封装和私有属性

一个简单的例子

class User:
    def __init__(self,birthday):
        self.birthday = birthday

    def getAge(self):
        return 2020-self.birthday

if __name__ == '__main__':
    user = User(2005)
    print(user.getAge())

注意：python封装使用双下划线，​​self.__birthday = birthday​​

class User:
    def __init__(self,birthday):
        self.__birthday = birthday

    def getAge(self):
        return 2020-self.__birthday

if __name__ == '__main__':
    user = User(2005)
    print(user.__birthday)
AttributeError: 'User' object has no attribute '__birthday'

​​__birthday​​​等价于​​_classname__birthday​​

user = User(2005)
print(user._User__birthday)

因此它并没有从语言层面上解决了私有属性的绝对私有性

假设再加一个类继承​​User​​

class User:
    def __init__(self, birthday):
        self.__birthday = birthday

    def getAge(self):
        return 2020 - self.__birthday


class Student(User):
    def __init__(self, birthday):
        super().__init__(birthday)
        self.__birthday = birthday


if __name__ == '__main__':
    user = User(2005)
    stu = Student(1006)
    print(user._User__birthday)
    print(stu._User__birthday)

这种变形机制，解决了同样变量名冲突的问题