Path: utzoo!attcan!uunet!decwrl!shelby!neon!hoelzle From: hoelzle@Neon.Stanford.EDU (Urs Hoelzle) Newsgroups: comp.object Subject: Re: prototypes and degenerate cases Message-ID: <1990Sep18.155754.23323@Neon.Stanford.EDU> Date: 18 Sep 90 15:57:54 GMT References: <1990Sep16.083629.10936@tukki.jyu.fi> <1990Sep18.041532.14401@tukki.jyu.fi> Organization: Computer Science Department, Stanford University Lines: 22 sakkinen@tukki.jyu.fi (Markku Sakkinen) writes: >>[ explanation how circles / ellipses can change representations in a >> prototype-based system like Self ] >I am sorry, but there seems to be a little confusion still. >In a prototype-based system, "inheriting" a data slot from a parent object >means _sharing_ it with the parent. Surely Bruce Cohen's intention was not >that when a circle becomes a ellipse, it has to share all the instance >variables of some prototype ellipse thenceforth. >(I have not read the paper mentioned, but the above is obvious anyway.) I am sorry, but there seems to be a little confusion still... ;-) The parent object is a *clone* of the {circle,ellipse} prototype, not the prototype itself. Every circle has its own "data parent" holding its state, and all circles have a common parent holding common behavior (and possibly common state, if needed). With object-based inheritance, an object can inherit from any other object - there's nothing special about the prototype. But I think the above is obvious anyway ;-) >Markku Sakkinen