[Chandler-dev] Observers and stamps

[Brian Kirsch]

Hi Jeffrey,
See comments inline.



-Brian



On Nov 28, 2006, at 3:53 PM, Jeffrey Harris wrote:

> Hi Folks,
>
> I have code in EventStamp (on the recurrence branch) that says:
>
>     @schema.observer(ContentItem.collections)
>     def onCollectionChange(self, op, name):
>         ...
>
> I just realized that this observer gets called every time an item is
> added to (or removed from) a collection, not just when EventStamps are
> added to collections, because it's watching an attribute that doesn't
> live on EventStamp.
>


To implement the new In / Out collection logic I have added observers  
on MailStamp itself to detect changes in the fromAddress, toAddress,  
etc.



> I think for my use cases, I'd be happy to have observers on stamps  
> only
> get called if the item in question has that stamp.  Do other folks  
> have
> use cases where they want observers to apply to all items,  
> regardless of
> stamp?

No

> Would it be reasonable for those observers to always live on
> ContentItem?

> If so, it seems like we could save ourselves a bit of method  
> calling by
> checking stamps before calling observers.  I'm not sure that  
> that'll buy
> us all that much, method calls aren't all that expensive, but it would
> be interesting to see if it buys us anything.  It also seems
> conceptually cleaner to me.

+1
I could see having stamping detection for observer callbacks as a  
very valuable feature although I do not have a specific need for it  
at this time.


>
> Thoughts?
>
> Sincerely,
> Jeffrey
> _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
>
> Open Source Applications Foundation "chandler-dev" mailing list
> http://lists.osafoundation.org/mailman/listinfo/chandler-dev