python学习之描述符自制property

class lazyproperty:
   def __init__(self,fun):
      self.fun=fun

   def __get__(self, instance, owner):
      print("get")
      print('===========>',self)
      print('===========>',instance)
      print('===========>',owner)
      if instance is None:
         return self
      res=self.fun(instance)
      setattr(instance,self.fun.__name__,res)
      return res

class Room:
   #area1=lazyproperty(area1)
   def __init__(self,name,width,length):
      self.name=name
      self.width=width
      self.length=length

   @property #把一个函数伪装成一个属性
   def area(self):
      return self.width*self.length

   @lazyproperty
   def area1(self):
      return self.width*self.length

r1=Room("卧室",6,5)
# print(Room.__dict__)
# print(r1.area) #实例调用
print(r1.area1)
# print(Room.area) #类调用
# print(Room.area1)
print(r1.area1)
print(r1.area1)