[vtk-developers] Class Event Observers
David Cole
david.cole at kitware.com
Thu Aug 11 12:11:45 EDT 2005
I second the call for a sample use case posting...
It's gotta be good, too; I'm already biased against singletons in
libraries... Singletons are much more manageable in the final
application (the library client, not the library) in my opinion.
David
Brad King wrote:
> Goodwin Lawlor wrote:
>
>> I'd appreciate any thoughts people may have on a proposal for
>> class/global event observers.
>
>
> Can you post a sample use case for this please?
>
> Also, whatever decision results from this discussion please do not try
> to add this before the upcoming VTK 5.0 release. I don't want to get
> the interface wrong the first time and then have to support it because
> it was in a release.
>
>> One way I thought of implementing this is to add a static member
>> pointer to each class, pointing to the first class observer.
>> Something like:
>>
>> static vtkObserver *GlobalStart;
>
>
> This is a singleton, so you will have to implement careful management
> of it. Somehow all the observers must be destroyed on exit, but if
> they are not destroyed early enough their destructors may have already
> been unloaded! Look at vtkFilteringInformationKeyManager and
> vtkDebugLeaksManager for example approaches to do this.
>
> -Brad
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