Hello everyone, I've been trying out a pre-release of g++ 4.0, and its typeof now works a lot better than the older versions. This allows it to be used for metaprogramming. As an example, I've attached a compile time factorial implemented mainly using operator overloads (it's not commented at all, but should be pretty easy to understand for most people on this list). I think it would be possible to write a metaprogramming library which would have much nicer syntax (borrowing techniques from lamba & phoenix), and integrate well with mpl. I suppose that since such a library would only work on gcc for now (or do any other compilers have a good enough typeof?), it might not be appropriate for boost, but I thought this might be of interest here anyway. Daniel