[Tutor] Class Attribute "Overloading?"

[Kent Johnson]

Tiger12506 wrote:
> It's a little ugly but not too bad. What you are describing are properties.
> 
> class Foo:

should be
class Foo(object):

>   def _get_attr1(self):
>      if not self.attr1:
>         attr1 = TheValue
>      return attr1

You have to use a different name for the actual data attribute and the 
property (stack overflow, anyone?), and you didn't save the value.
      if not self._attr1:
         self._attr1 = TheValue
      return self._attr1

>   def _set_attr1(self, value):
>      self.attr1 = value
>      ChangeDBFunction(value)
>   attr1 = property(self._get_attr1,self._setattr1,None,None)

A read-only property might be more appropriate (no _set_attr1).
> 
> I think that will work. The docs seem to suggest that you should subclass 
> `object`.

That is required. Properties do not work correctly with old-style 
classes (not derived from object).

Kent