Re: [Swingosc-devel] "failed to start" message

[Sciss <co...@sc...>]

well spotted! i removed Model now as a superclass

Am 27.06.2010 um 08:20 schrieb James Harkins:

>> 
>> hmmm,
>> 
>> updatelistener per se is very robust and first 100% correct, i have it all over the place in my live instrument. so if there is a bug it must be somewhere outside of it, maybe a missed registration or a race condition, or....?
>> 
>> at the moment i don't have time to look into it (also since i never witnessed this problem), but will keep it in my mind. if you have a startup sequence that reproduces the problem (without relying on extra quarks), i could see if i find the issue.
>> 
>> 
> 
> Arghhh... I think I found it. SwingOSC is a subclass of Model, which 
> doesn't include the fix that was made to Object:changed to avoid 
> iterating over a collection from which items might be removed.
> 
>     changed { arg what ... moreArgs;
>         dependants.do({ arg item;
>             item.update(this, what, *moreArgs);
>         });
>     }
> 
> The only thing about my startup sequence that I can find is that I use 
> SwingOSC.default.waitForBoot in my startup file, which calls 
> doWhenBooted. SwingOSC:boot also calls doWhenBooted -- so there's a pair 
> of UpdateListeners. I'm almost certain what's happening is that one of 
> these listeners fires and removes itself from the dependents collection, 
> which then modifies the collection so that the iterator never touches 
> the other listener.
> 
> I'll do some more testing by changing the method to read 
> dependants.copy.do (to match Object:changed).
> 
> CC: sc-dev, so I can rant about the continued existence of Model. I can 
> see that it's there to improve performance of dependent notifications 
> over Object's dependantsDictionary -- but, because supercollider doesn't 
> have multiple inheritance, subclassing Model means that you can't 
> subclass anything else at the same time. So nobody uses Model, with the 
> side effect here that an important fix to the dependency protocol in 
> Object never made it over to Model, and it wasn't discovered for 
> probably a couple of years.
> 
> Mental note -- SC4 cleanup -- remove Model.
> hjh
> 
> 
> -- 
> 
> James Harkins /// dewdrop world
> jam...@de...
> http://www.dewdrop-world.net
> 
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