CAS and Squeak

Jarvis, Robert P. (Contingent) Jarvisb at
Tue Jun 5 15:25:51 UTC 2001

> From: Sam Adams [mailto:ssadams at]
> <snip!>
> This is a pattern (Metatype-Genotype-Phenotype, or MGP) that shows up
> frequently when modeling domains that include class/instance 
> relationships.
> Its a bit too "meta" for most folks, but its very powerful, 
> in my view one
> of the 3 most powerful complexity reducing patterns known, 
> the others being
> Ward's "Whole Value", aka make your objects model your domain, and
> "Thing/GroupThing" (TGT), a slightly more complete form of 
> the "Gang of
> Four" composite pattern.  Whenever I have a design where all 
> three of these
> patterns can be applied in concert, I get extreme reduction in the
> complexity of the design and a resulting object model with incredible
> expressive power while staying true to the domain.

Is there a web page or other reference you could suggest describing these
patterns? I found a reference for the "Whole Value" pattern at, but could find no references to MGP or TGT.

Bob Jarvis
Compuware @ Timken

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