On Sat, 2007-10-27 at 11:08 -0400, Arkadiy Vertleyb wrote:
"Eric Niebler" <eric@boost-consulting.com> wrote
In order for BOOST_TYPEOF to work with xpressive's static regexes (something I'm actively trying to support), I need registrations for reference_wrapper<> and mpl::int_<>. I'm happy to add them, but I'm not sure where. Thoughts?
Looks like the model where authors are responsible for registering their own classes dosn't work quite well... Maybe there should be a designated place with collective ownership, where interested users could add such registrations? This place could mimique the boost directory structure, to avoid conflicts, something like:
typeof_registrations mpl bind xpressive spirit ...
There are several libraries that have this kind of problem. typeof needs registrations, serialization needs serialize() functions, MPI needs datatype traits, etc. I wonder if we can solve this problem for all of Boost with some kind of automatic scheme that says: if you include header A from one library and header B from another library, you automatically get whatever glue makes A and B work well together. It's relatively simple to implement this for two headers. In header A you have: #ifdef HEADER_B_INCLUDED # include <glue_a_and_b.hpp> #endif In header B you have: #ifdef HEADER_A_INCLUDED # include <glue_a_and_b.hpp> #endif For the general case, we would probably want a "glue" subdirectory whose directory mimics the Boost directory structure (like a generalized version of your typeof_registrations suggestion). Each header in "glue" would have a bunch of #ifdef's checking all of the various other library/header names and including the appropriate glue code. Overall, it's O(N^2) work in the number of data structures/headers/libraries (depending on how we chop it up), but users would get all of the important glue "for free". - Doug