[ENH] EventEnhancement-nk
John W. Sarkela
sarkela at sbcglobal.net
Wed Jun 18 15:20:43 UTC 2003
On Tuesday, June 17, 2003, at 04:30 PM, Andreas Raab wrote:
> Because of the above, I'm pretty certain you will have more discussions
> coming up about this in the future. Funny enough, the history of using
> events in Squeak is quite interesting in this regard:
> * first (I think) Stefan Matthias Aust wrote a first version - strong
> refs
> * then I changed this - weak refs
> * then John's version went in - strong refs
> * then Rob changed it - weak refs
> So now it looks we'll go back to strong refs.
Very nearly almost, but not quite right. Stefan's version was the first
incorporated by Squeak central into the image. There were earlier
Squeak ports by others.
The real history of the mechanism follows.
* George Bosworth made some inventive changes to changed/update in
Smalltalk/V.
* Steve Messick refined and designed the current form of events,
introducing when:send:to;.
* The Dolphin guys (Blair and Andy) looked carefully at VSE and
included events and exceptions VSE style and incorporated them into
Dolphin Smalltalk. (A truly beautiful and well thought out product BTW.)
* I suspect Stefan got his ideas from the Dolphin port, in the process
he missed the use of events as an information provider, the #needsXXX
event pattern. He also missed the inherent sequencing of registrations.
The bulk of the credit for the version currently in VW and Squeak
really belongs to Steve Messick. Probably one of the finest object
designers I have ever known. All I did was write the smallest amount of
code that passed the tests for the existence of Steve's design ideas.
> I wonder for how long ;-)
How about as long as the simplest possible solution can work. I know
that strong changed/update dependency has worked just fine for over two
decades. :-}>
:-}> John Sarkela
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