callback strangeness?

[Rob Gayvert]

Cees de Groot wrote:

> On Tue, 15 Mar 2005 18:40:30 +0100, Cees de Groot <cg at cdegroot.com> 
> wrote:
>
>> However, I just realized that the p2p search sends global 
>> references,  not actual objects, in some cases. Reference resolution 
>> times out after  two seconds, so that could be the cause of this. 
>> I'll investigate more...
>
> Yup. That's it. I paint different icons in the list, the test needs 
> to  resolve a global network link to see what icon needs to be 
> returned. So  the #onGetItemImage: callback takes around 2 seconds. 
> This seems to  severely mess up everything else (which, IMHO, means 
> that there are still  some holes in the call back handling - whether 
> the callback takes 2  nanoseconds or 2 years should not make a 
> difference in how wxSqueak works,  should it?)
>
> Oh well, not much I can do to that for now, can I?

With a virtual list control, #onGetItemImage: get called once for each 
item in the list each time that the list is displayed, so if the 
callback takes a significant amount of time this is going to make the 
GUI very unresponsive. I think you'd be much better off with some kind 
of asynchronous update to the list.

That's not to say that the callback handling doesn't have holes, because 
it does ;)  But even after we get it plugged, it will be a good policy 
to keep callbacks as short as possible to make the UI feel fast.