[boost] compose_f_gxy_hxy

From: Daniel Frey (d.frey_at_[hidden])
Date: 2003-06-25 18:08:24

Inspired by an article at the CUJ from Andrei Alexandrescu, I was
finally able to come up with a compose_f_gxy_hxy-adapter. I think that
it's the missing adapter to make compose.hpp complete. In the companies
production code, I needed it and used a much easier implementation with
some limitations, so it's not just a toy example.

The code attached is a first cut, tested on Intel C++ 7.1 and GCC 3.3.
The GCC 2.95.3 has problems with it I haven't solved yet (and I don't
know if it's possible at all). Anyway, I'd like to hear some comments
whether it's a good idea and should be pushed forward or if it better be
buried :)

I attached a modified compose.hpp and a new file for the same directory
where I put the type selection code, called combined_argument_type.hpp.
It needs some boostification and you need to read Andrei's article to
understand it. Really. :) Andrei's article can be found here:

http://www.cuj.com/documents/s=7996/cujcexp1904alexandr/alexandr.htm

As I put the implementation into a separate file, it should now also be
easy for boost to provide min/max (probably in utility.hpp?) like
suggested by Andrei if requested - although I'm not totally convinced
it's a good idea as IMHO min/max should have value semantics (the
currently have AFAICS) and not reference-semantics, but that's another
story.

To complete the implementation of combined_argument_type, it would help
if mpl::vector would have 16 instead of 10 arguments, but that can be
done later if there is interest in compose_f_gxy_hxy. I currently simply
removed the first types of the type-list, I've just been lazy, so don't
wonder how this should work. It won't. :)

Comments?

Regards, Daniel