Thanks for that Simon. I think I did see the query() function... But it did not register until now.
Indeed, I would prefer hierarchy in my file types... but experience tells me that's not trivial. Sometimes there are more than one useful hierarchies, so building a useful one can be difficult (I gave it my best shot for now). The "Union" solution: I am sort of reluctant to use unions (I don't quite find it as elegant as the inheritance system). Also, there is a change in Union syntax from v0.3->v0.4. But, since Julia's current release is finally at v0.4, I should really migrate ASAP. That being said, I still like your suggestion: The good thing about your Union solution is that it allows the *user* to select which filetypes are grouped, and how. I must give this serious thought. As for the dynamic loading: I can't really comment yet. I will have to get used to that system a bit more before I can have a real opinion. Regards, MA
