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Date:Mon Aug 26 15:26:20 1994 
Subject:Objectclass 
From:James Anderson 
Volume-ID:940827.02 

I have been an object oriented programmer for nearly three hours now.
I am using Objectclass in Poplog version 14.2.

I have defined a class whose slots are continuously variable parameters.
I want to define sub-classes of this class that have non-overlapping parameter
ranges within the superclass range: think of dwarfs, people, and giants who are
defined to be apes with non-overlapping ranges of heights.

How do I specify, or enforce, constraints on the slot fillers of an instance?

If the filler for a slot exceeds the allowable parameter range can I automatically
search the inheritance hierarchy for an acceptable sub-class and return an 
error instance if none is found?

Am I asking too much of object oriented programming?

(Yes, I know that another three hours of reading Steve's files and working through
Aaron's amusing teach files would probably settle the matter, but I've had enough for
one day and I could realy do with the answers before I take too many more
design decisions.)

James Anderson