A good while ago I got interested in how the registration process works in boost::serialization, I was never able to understand how the technique works, even if the gist of it is contained in 2 fairly small headers ( boost/serialization/export.hpp & boost/archive/detail/register_archive.hpp ). It would seem the creator of the technique is David Abrahams, so I'm hoping he or anyone else which understands how the registration process works could explain the technique used.

From my understanding it solves the problem of having 2 different sequences of types, and then being able to operate on all the combinations. All the techniques I've seen used previously for this requires the maintenance of some sort of compile time vector of one of the sequences. This is very cumbersome, not only does it needs to manually managed, but the file that defines the vector turns into a large dependency bottleneck. From my understanding the technique used in boost::serialization currently one sequence simply adds an overload to a free function, then at the registration point of the other sequence just having the overloads considered at compile time causes the magic to happen when the return type needs to instantiated. Unless I'm missing something obvious I think it would make for a very interesting subject of an article or discussion on the mailing list.

Kind regards, Sebastian Karlsson