abstract variables proposalQQ

Ramon Leon ramon.leon at allresnet.com
Wed Nov 29 18:00:33 UTC 2006

> One of my fustrations in using Smalltalk is that I may have a 
> subclass B with a number
> of subclasses,  say  C,D,E,F   and such that some of the 
> subclasses, say C and D, 
> need to access an instance variable, say  b,  but the 
> remainding classes,  say E and F, do not need to access 
> variable  b.  In this situation I have two basic options:

Would you mind stating a real world example of this scenario?  I ask because
I have the feeling the problem is more related to design of the class
hierarchy than to anything wrong with Smalltalk.  If E and F don't need all
the instance variables of B, then they simply shouldn't subclass B.  

Subclasses should only extend the behavior of a parent class, not restrict
or change it, so I'm curious on seeing a real example of this issue.

Ramon Leon

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