如何防止类属性被外部类修改

class MyClass:
    __my_attribute = 10

    def get_attribute(self):
        return self.__my_attribute

    def set_attribute(self, value):
        self.__my_attribute = value

obj = MyClass()
print(obj.get_attribute())  # 输出: 10
obj.set_attribute(20)
print(obj.get_attribute())  # 输出: 20

class MyClass:
    _my_attribute = 10  # 前面加上单下划线表示属性是受保护的，不建议直接访问

    @property
    def my_attribute(self):
        return self._my_attribute

    @my_attribute.setter
    def my_attribute(self, value):
        # 在setter方法中可以添加条件判断，限制修改的规则
        if value > 0:
            self._my_attribute = value

obj = MyClass()
print(obj.my_attribute)  # 输出: 10
obj.my_attribute = 20
print(obj.my_attribute)  # 输出: 20

class MyDescriptor:
    def __get__(self, instance, owner):
        return instance._my_attribute

    def __set__(self, instance, value):
        if value > 0:
            instance._my_attribute = value

class MyClass:
    _my_attribute = MyDescriptor()

obj = MyClass()
print(obj._my_attribute)  # 输出: None
obj._my_attribute = 10
print(obj._my_attribute)  # 输出: 10
obj._my_attribute = -5
print(obj._my_attribute)  # 输出: 10，因为值小于等于0，修改无效