class Screen(object):    @property    def width(self):        return self._width    @width.setter    def width(self,value):        self._width = value    @property    def height(self):        return self._height    @height.setter    def height(self,value):        self._height = value    @property    def resolution(self):        return self._height * self._width

**PS：**只设置@property不设置@xxx.setter就是只读属性，还可以设置@xxx.deleter用于删除属性