Hi everyone - I'm kinda researching Functors right now. I wrote my own naive functor for the first iteration of my engine, but now I want something far more fully featured... I've been reading about Loki's functor - which seems nice, but really complex... I admittedly don't know too much about Boost's functor, which I understand is implemented totally differently. Does anyone here have any experience with them, who might be able to simply describe the differences, give some opinions on which one is better? Thanks for any help!

I find boost::function<> to be easier to use. It's also being added to the C++ standard so you'll start seeing it distributed with your C++ implementation soon, or as part of a TR1 package.

A bunch of alternatives have shown up on codeproject over the years, which have different performance characteristics.

OTOH, Loki's is a little more flexible, especially with respect to the threading model.