Sorry about the slow reply. 2008/11/10 David Abrahams <dave@boostpro.com>:
If I could prevail upon Daniel James to add iterator_to to Boost.Unordered so it will be there in the future, I'd gladly backport that change into my version
I'm not sure if it's that simple. The nodes aren't PODs so I don't think 'offsetof' can't be used to get their address (or can it? I've never used it). MultiIndex copes by using aligned_storage and manually constructing the value in place, so that it can get the containing structures address. Which is a possibiliy for the unordered containers, and could help implement emplace for compilers without variadic templates (or for allocators without a variadic construct method) so it might be a good idea anyway. So I'll look into doing that. Daniel