''A recent email exchange ...''

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Ward -- Recently we had a pleasure of working with BarbaraYates and JanSteinman 
on the design review of our current project.  We chose PipesAndFilters 
architecture for the software.  Jan mentioned that you and KentBeck worked on a 
similar problem in the past.  I searched Smalltalk Archive and PPR for any 
pointer to the results of that and was not successful.  Do you know of any 
document or source code(in public domain) that I could leverage of in 
developing generic abstract filter and/or pipe classes?
-- JerzyBilchuk

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Jerzy -- He must be thinking of the educational simulator I wrote for the FirstAdvancedSmalltalkClass. It was called Plumbin'. The name is a takeoff of
Truckin', a knowledge engineering simulator built at Xerox PARC in the
same period -- mid 80's. Plumbin' was inspired by the child's card game,
Waterworks, where you play pipe cards like dominos to connect faucets to
spouts. I modeled four or five fluid devices (pipes, valves, pressure
tanks, etc.) Each had views that could animate the real-time behavior
(state, pressure and flow), and controllers with which one could
intervene. 

One of the students was so taken by the power and simplicity of the
whole thing that he founded a five year development project at a major
chemical manufacturer to duplicate the thing on a chip. The result was a
programmable part that could model and control chemical processes,
communicate by fiber with similar parts, and generate a video animation
of everything it did as it did it.

	* http://c2.com/doc/plumbin

I learned a bit about collaboration on what was in fact my first project
involving Kent. I wrote the thing in a few days and then polished it for
a few more because I wanted the students to read and enjoy the code. I
gave a copy to Kent and asked for his comments. I wasn't expecting
anything but praise. Instead he gave me modifications. Hurmph. I
considered discarding them. At the last minute I put the mods in, all of
them. I felt the program slipping as I did. But, lo, it was just my
imagination. The program didn't decay after all. In fact it held up
quite well. What did decay was my defensiveness. You can't collaborate
without letting go of something. 
-- WardCunningham

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Just wanted to let you know that the sources for Plumin' have helped me
understand
Squeak better. I've gotten the sources running and have started enhancing.
I added a
MosaicController object which pops up a menu allowing one to add new tiles
to the model.
Its helping me understand how to work in the MVC enviroment.
Thanks again.
-- ErikHusby