Thomas Witt <witt@acm.org> writes:
Yes, the whole area of dispatching and customization of generic functions is nasty in C++. I've known it's problematic for a long time, but had a hard time expressing how bad the problem is in a way that would communicate to someone who doesn't do heavy generic programming day in and day out.
I agree that something needs to be done. I just really want to be convinced that the proposed changes to boost::begin are the right solution
Without going into the description of the language problems too deeply, here's a prototype of what Doug and I came up with. So far it only compiles for me with g++. Things to notice: - ADL is limited to *one* name, lookup_implementation() - ADL is decoupled from the actual types being passed to algorithms via their category tags - You can write generalized lookup_implementation() functions like the one shown, that choose some rules by which to dispatch all algorithms - You can write specific lookup_implementation functions to set different rules for particular algorithms. -- Dave Abrahams Boost Consulting www.boost-consulting.com