[Zope3-dev] storing per instance data in principalannotation

[Christian Heimes]

Hello!

I just start working with principalannotations and I'm trying to add 
some features for me. One feature is the ability that each instance can 
store data for each principal. This is like a kind of combination of 
attributeannotations and principalannotations.

I thought of this way:

* instance is querying for the annontation object of a principal:
   a = getService(self.context, 
'MyPrincipalAnnotation').getAnnotation(self.request.user)

* instance is using a special method to store it's data:
   a.perInstanceData[self] = data


The perInstanceData method of the principalannotation class works like this:

* the key 'self' is converted to a RUID via object hub

* if there the key is already in the per instance data OOBTree the new 
data is writen to the OOBTree

* if not the principal annotation service is told that there might be a 
new instance that has to be monitored, then the data is saved.

QUESTION: How can I access the right principal annotation service? Can I 
use getService and safely assume that I got the right service or should 
I pass the service to the principal annotation as an option?


The principal annotation service keeps a list of all instance RUIDs that 
had saved data in a principal annotation. The service monitors all this 
instances for IObjectMovedEvent, IObjectCopiedEvent and 
IObjectRemovedEvent via event hub. If it catches one of these events, it 
iterates over all principal data and changes/deletes the corresponding data.

QUESTION: Is this way ok or does anybody know a better one? Would this 
be a nice feature for the Zope3 principal annotation? If you have any 
comments or suggestions you can reach me in #zope3-dev, too. My nick 
name is Tiran.

Christian