[cgma-dev] Observer question?

[David Thompson]

>> ...
>> The notify_observer() method called on observers doesn't appear to provide information about the entity(-ies) replacing those being modified. Is there a way to obtain the resulting split or merged entities? If I create an attribute to hold an ID on faces or edges of interest, how fast will lookup be?
> 
> If it's anything like ACIS, you generally don't know the correspondence between an entity that gets deleted and the ones used to replace it.  IIRC you don't get many notifications of split or merge type, only of delete type (and implicitly create type, which show up as not having associated CGM entities yet).


Hmm. If different engines behave differently, then I guess we shouldn't rely on it for tracking persistent geometry across operations. Would you advise adding UUIDs as attributes for that kind of tracking?

	Thanks,
	David