Thanks Lukas
So for magritte GemStone port, I will let the MADescriptionBuilder build and cache the description for objects if it doesnt already exist in the cache and since code chages will be very rare in a production enviorment, i leave out MABuilderDescription subscription to SystemChangeNotifer for method chages in the System
 
Cheers
ISaiah
> Date: Wed, 10 Oct 2007 13:34:20 +0200
> From: renggli@gmail.com
> To: smallwiki@iam.unibe.ch; beta@seaside.gemstone.com
> Subject: Re: [GS/SS Beta] SystemChangeNotifier & MADescriptionBuilder
>
> > To build a metadescription of an object Magritte per default only
> > looks a the class side. It collects all the selectors the class of the
> > object contains that begin with 'description' and performs them. This
> > can take a moment on Squeak so a cache was added that maps classes to
> > metadescriptions. This cache will have to be invalidated if a class is
> > changed (a method added or removed).
>
> The cache is only useful if you need to traverse a collection of
> thousands of objects that mostly share the same descriptions. Like
> this, descriptions don't need to be recreated all the time. This
> significantly speeds up the traversal.
>
> > PS: looking at the squeak implementation it seems that MADescriptionBuilder
> > flushes its cache of description if any method is changed or modified or
> > added in the entire System, not necessrily an object in the
> > MADescriptionBuilder cache
>
> This is the simplest thing that reliably works. It could be that you
> call other methods from the code that builds the descriptions (for
> example, if you extract default values to separate methods), that
> could affect the settings of the descriptions. In a productive system
> the cache fills up pretty fast. Since code changes in a productive
> system are rare this is not an issue.
>
> Lukas
>
> --
> Lukas Renggli
> http://www.lukas-renggli.ch
>
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