Comparator is a small Plone product I recently hacked for my pleasure. It’s called comparator until it gets a nicer name, if ever. I distribute it here under the GNU General Public License. It allows users to select any existing content type (object class) and to calculate a personnalized comparison of the instances of this class. For example, if you choose to compare « News Items », then you select the news items properties you want to base your comparison upon (title, creation date, description, …). You give marks to any value of these properties (somewhat a tedious process at the moment but much room for improvement in the future, there). Comparator then let’s you give relative weights to these properties so that the given marks are processed and the compared instances are ranked globally.
It’s a kind of basic block for building a comparison framework, for building Plone applications that compare stuff (any kind of stuff that exists within your portal, including semantically agregated stuff). Let’s say that your Plone portal is full of descriptions of beers (with many details about all kinds of beers). Then adding a comparator to your portal will let your users give weights to every beer property and rank all the beers according to their personal tastes.
Comparator is based on Archetypes and was built from an UML diagram with ArchgenXML. Comparator fits well in my vision of semantic agregation. I hope you can see how. Comments welcome !