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

s = Screen() s.width = 1024 s.height = 768 print(s.resolution)