@property

@property装饰器负责把一个方法变成属性调用

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.__width * self.__height

# test:
s = Screen()
s.width = 1024
s.height = 768
print(s.resolution)
assert s.resolution == 786432, '1024 * 768 = %d ?' % s.resolution