Re: Meaning of Alt

Graham Klyne wrote:
..> > Enumerated types can also modeled as
> >subclasses or instances but sometimes it is just more natural to put
> >some things in a bag and say "pick one". Something like the colors on
> >a stop light can reasonably be modeled in this way rather than
> >introducing a totally artificial "stop_light_color" class.
> Hmmm... I think this is in danger of conflating union types with
> alternative values.
> (An enumeration type can be viewed as a union type of its individual
> enumerated values)
> If this is being used in the context of a type definition schema, then
> comments make sense.  But it seems to me that the primary use of rdf:Alt
> would in the _value_ of some _instance_ of a type, so the issue of
> enumeration does not arise -- it's just a value.

    Reading the spec I see no support for any particular interpretation of
Alt other than it represents one of a set of members. So
{"red","green","blue"}, to me, represents a set. Seq implies on an ordered
list of members, perhaps repeated. Alt implies one of the set. Why not allow
the Schema designer the choice? Can actual harm result beyond an offending
of sensibilities?

Jonathan Borden

Received on Thursday, 7 September 2000 17:44:44 UTC