[Zope-dev] An idea for UniqueValuesFor

I quite often need to do something like: results = MyCatalog(meta_type='Person',continent='Africa').uniqueValuesFor('FirstName') ...which would give you the minimal list of firstnames of people who live in Africa. A bit contrived but I seem to bump into lots of real world cases where I need to do similar. What I currently have to do is the brutal and slow approach of "walk through the results" :-S But Anthony came up with a great suggestion:

What would make more sense (maybe?) is results = MyCatalog(meta_type='Person',continent='Africa',uniqueValuesFor='FirstName')

What do other people think? Is there a nice fast way of implementing this? cheers, Chris