I do not care which is faster.

Could've fooled me, based on your question. At least half of it is dedicated to talking about the speed... but I digress. :-)

I only care what is the best design.

If you want to know how other people feel about it, then I think the best option would be a design similar to the one chromatic described. But if you are set on using callbacks, then you can mark me down in the "argument passing" column.

Well, I'd like to know what the speed is, but I don't really care. I mean, my laptop is 1ghz. My workstation box is 2ghz. Plus this is (as someone else mentioned) I/O intensive. I want it to be clean, and I'm merely curious about speed.

Now, as to callbacks. I'm using them because of the problem domain I'm trying to fill. The problem domain is to make something to allow me to replace ttree (an ugly script that comes with Template Toolkit). Which means I need to do different things depending on the filename.

This design fits my problem very well, and *maybe* it'll fit other people's problems, too. There is always File::Find::Iterator on CPAN already for those that want iterators. The real usefulness of this module is to be able to say "process all .pl files with this function, and process all .pm files with this function, etc".