[Zope3-Users] How to prevent several notifications of events ?

[Thierry FLORAC]

On Thu, 2006-06-01 at 12:27 +0200, Florent Guillaume wrote:

> Thierry FLORAC wrote:
> > I've build a simple adapter that modifies context properties through
> > annotations ; everything works fine.
> > In several cases, when some attributes are updated, I do a
> > "notify(ObjectModifiedEvent(self.context))" so that several subscribers
> > are called.
> > 
> > My problem is then that if several attributes modifications are done,
> > several "ObjectModifiedEvent" are sent and the same handler is called
> > several times (with the same parameters) ; so is it easily possible to
> > prevent the same event to be called several times for a same context and
> > a same request ?
> > Or should I try to use request annotations and subscribe to
> > IEndRequestEvent (if it's not too late and not too expensive...) ?
> 
> Yes that's the proper way to do compress events: record the stuff to do, and 
> do it at the end of the request.
> 
> Depending on the stuff to do, it may involve subtleties, for instance if you 
> modify one object then delete it in the same request, you don't want to call 
> your final handler for that object...


Thanks for the reply, but I'd like to have a few complements :
 - I suppose that IEndRequestEvent is sent automatically for every
request, so even for consultation requests which doesn't imply any
modification. So I suppose that the IEndRequestEvent handler have to be
VERY optimised if I don't want it to be too expensive.
 - what is the best way to keep track of objects having been modified
(and which, for example, should be re-indexed) into request annotations.
Can I just put an object into an annotation's list (with a kind of
"IAnnotations(request)['myKey'].append(context)") ??

Thanks,
Thierry


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