Message-ID: <31C63F19.77A9@3-cities.com>
Date: Mon, 17 Jun 1996 22:31:05 -0700
From: "Travis Griggs (and Kerrin and Courtney too)" <tkc@3-cities.com>
Reply-To: tkc@3-cities.com
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Subject: Re: Questions about System Dependency Events
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Travis Griggs (and Kerrin and Courtney too) wrote:
> 
> I have some questions about the SystemDependencyEvents application that
> now ships as an optional filein for VW2.5. To begin with - how true to
> the Digitalk generalized event model is it?
> 
> I like it and find it to be an improvement over the traditional
> DependentsFields mechanism found from ParcPlace for three reasons:
> 1) more robust (can have blocks and variable number of arguments, etc)
> 2) more semantically clear (when:send:to: at the object level instead of
> onChangeSend:to: for only subclases of ValueModel)
> 3) wider bandwidth possible (now trying to sort it all out with complex
> update: statements, or hooking up a gazillion dependency transformers)
> 
> Given that, does any one know what PPD's plan is for this stuff? Are
> they going to refit ValueModel so it sends
> 
> self triggerEvent: #value
> 
> instead of
> 
> self changed: #value?
> 
> And so on and so forth?
> 
> And last of all for right now, why are the dependents/event handlers in
> either system bound to the triggering objects weakly? I've been using

boy, am I tired, above should read "...system NOT bound..."

> VisualWorks for four plus years now and this has always puzzled me? Why
> not just use WeakArrays/WeakDictionaries so that copious amounts of
> 'release' code don't need to be written?
> 
> Travis Griggs
> tkc@3-cities.com
