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):        self.__resolution = self.__height * self.__width        return self.__resolution# 测试:s = Screen()s.width = 1024s.height = 768print('resolution =', s.resolution)if s.resolution == 786432:    print('测试通过!')else:    print('测试失败!')print(dir(Screen))

我在最后print了Screen的dir，发现他的属性里有'height', 'resolution', 'width'这三项，也就是说通过@property和@func.setter把方法转换成了属性。不过在转换的过程中，有调用 .__width .__height 和.__resolution 这三项，为什么在dir里不会出现这三项呢？很疑惑，求解答