[Chandler-dev] Stamp/Annotation-related questions

[Grant Baillie]

Hello, chandler-dev@ (and pje in particular :):

So, as I plough on through stamping-as-annotations, I found some  
issues that are more related to using annotations than stamping per  
se. They're both cases where the annotation class has attributes that  
aren't repository values. I'd be interested in hearing if my  
strategies for solving these in the schema itself are reasonably, or  
if there's a better way of approaching things.

1) The osaf.pim.Calculated class (essentially, the analog of a python  
property) doesn't play quite so nicely inside Annotations. You can go  
ahead and do

class MyAnnotation(schema.Annotation):

     schema.kindInfo(annotates=pim.ContentItem)

     myProp = pim.Calculated(schema.Text, ....)



and then code such as:

     MyAnnotation(someItem).myProp = ... something or other ...

works just fine. The problem is that things like attribute editors  
(and indexes) want to talk to items  -- not Annotation/Stamp  
instances -- directly by attribute name. So, they require an item and  
an attribute name in order to edit or index something, but the  
property doesn't appear in the target class (ContentItem above). Is  
there a reasonable way to make this work? For instance, you could add  
a suitably wrapped property on the fly to the ContentItem class, but  
then you would have to be sure that this happened each time Chandler  
ran (i.e. it should happen at class object instantiation time, not  
parcel initialization time).

2) There are some similar issues with indexes. For instance, it's not  
hard to port the following code (parcels/osaf/pim/__init__.py):

     events.addIndex('icalUID', 'value', attribute='icalUID')

since I can just replace attribute with its full name (or use  
pim.EventStamp.icalUID.name if I don't want to hard-code the string).  
However, compare indexes are trickier, since they take a method name,  
e.g.

     events.addIndex("effectiveStart", 'compare',  
compare='cmpStartTime',
                     monitor=('startTime', 'allDay', 'anyTime'))

Here again I can use fully qualified attribute names in the monitor.  
However, the (str) value of compare keyword has to point to a method  
on the item class, not the annotation (stamp) class (since the  
collection, which is what's being indexed, contain items). Typically,  
though, I'd expect to write a method on EventStamp that does  
'cmpStartTime', so to do this I'd again have to wrap the method and  
add it to the target class somehow.

--Grant