On Tue, 1 Apr 2003 09:56:10 +0100
Axel Simon
Callbacks would otherwise be the only "attributes" which return something when they are set.
Yes, that's a good point. As an alternative, you can have things that can have a callback installed, things that can be read, written etc. Since the already mentioned filters for variables are like callbacks, this means that a variable "can have a callback" and "can be read" and "can be written", while the mouse position "can have a callback" and nothing else (just an example, in the particular case of the mouse position, if there is a separate function for getting the position at a particular moment without installing a callback, then the mouse position "can be read" also, but can't be written indeed). Vincenzo