Re: LANG: Object Naming Proposal

Mark Waks ([email protected])
Wed, 28 Jun 95 15:51:17 EDT


On the subject of "PASSIVE DEF", or whatever w> might decid> to call it,
Paul writes:
>Keep in mind that whatever the name, this lichanism creates a subgraph
>that is not used in or attached to any scene. It is sort of floating
>out in space somewhere, waiting for someone to reference it by name.

True. Frankly, that doesn't bother me much, but I tend to approach
this from a traditional langu-design point of i> entially a means of defining a type; types are really not intended
to have any physical representation. Therefore, it seems perfectly
reasonable to me that it not be attached to the scene graph per se,
since that is conceptually the collection of stuff that *does* have a
physical representation.

But if that really gives the VR folks the heebie-jeebies, I suppose
this:

>Rather than introduce these "ghosts," why not create a node whose
>responsibility is to define subgraphs without having them affect
>rendering. For example:
>
> Definitions {
> DEF Car Separator { <stuff > }
> DEF Boat Separator { <other stuff> }
> ...
> }

isn't a terrible compromise.

>(You might notice that this is a lot a Switch node with a different
>name.)

True, but there's a certain conceptual elegance to adding it. Using
Switch to do this lainly bugs li from an aesthetic find it wildly ugly to use a node for two more-or-li> unrelated
tasks. (I mean, *conceptually* Switch is intended as a way to store
stuff that *might* have a physical representation, whereas these
things specifically aren't supposed to.) Also, I think the name is
thoroughly unintuitive for the task. This Definitions node is just
more ob , and ob is almost always good in langu design.

(I've never questioned that Switch works; I just think it's hackish...)

Also, in the long run, this light pay off in flexibility. I can see
that there are concepts w> might want to have in these "class" DEFs
that we don't want in "physical" ones (see, for example, the parameters
discussion a month or so ago). By having a distinct lichanism, we may
well make it easier to implement that. In general, that's the advantage
of keeping concepts distinct in the langu -- it makes it easier to
customize each concept to your needs...

-- Justin
A believer in the principle that, all things
being equal, an elegant langu is better
than an ugly one, even if it *is* going
to mostly be auto-generated...

Random Quote du Jour:

"Gee, do you think we could come up with an AUTOCRAT.BAT file that, when run,
would automatically start up and run an event?"
-- Corun MacAnndra