Re: object algebra

"Patrick Schaaf" <mailer-daemon_at_bof.de> wrote in message news:403c5c29$0$143$9b622d9e_at_news.freenet.de...
> "Marshall Spight" <mspight_at_dnai.com> writes:
>
> >"Neo" <neo55592_at_hotmail.com> wrote in message news:4b45d3ad.0402241308.680a4901_at_posting.google.com...
> >>
> >> Sometimes it is reality doing the hand-waving. For example a person
> >> may not have any eyes, but the relation's heading has eyeColor
> >> defined.
>
> >But it wasn't reality that defined that relation, it was you! *You*
> >declared that all persons have an eye color, so it doesn't seem
> >fair to complain about that fact now.
>
> >And anyway, what's so hard about declaring something like
> >enum EYE_COLOR { Blue, Green, Brown, Hazel, Gaping_Unblinking_Sockets }
>
> >Hey, what if the person's eyes are of two different colors? Or what
> >if they only have one eye; don't we want to record that too?
>
> That's awful. To me it is obvious that, if that part of reality
> needs detailed modelling, there should be a class "eye", with
> an attribute "color" that's fixed for a given point in the
> lifetime of the object (eye color can change!), and that
> the separate object of class "head" may have, at any point
> in time, a reference to zero, one, or two instances of
> class "eye".

Your point about changing over the course of time is excellent. But I don't know if two is the appropriate maximum. I also think we should distinguish between people with one who used to have two, like a pirate, and people born with one, like Leela from Futurama.

> Such modelling, to me, may make real sense in the context
> of e.g. a medical database. Including the possibility to
> relocate an "eye" instance from one "head" to another.
> Including the possibility that an "eye" is not attached
> to any "head", but instead to a "cooling container".
>
> (play blade runner theme song here)

"I don't know such stuff. I do ... eyes." The fabulous character actor James Hong. He's been in over 100 movies; the Blade Runner appearance may be a career high. (Absolute nadir: "Femme Fontaine: Killer Babe for the CIA.) But you simply *must* see him in Wayne's World Two, if you haven't already. Best Martial Arts Scene Ever.

Marshall Received on Wed Feb 25 2004 - 09:41:12 CET