Re: [Boost-users] [multi_key] problems using modify_key with a composite_key index

Hello Jeff, Jeff Holle ha escrito:

Once again, I've run into a compilation problem that I can't seem to fix and I wish some help.

My multi_index container looks like:

typedef multi_index_container< entry, indexed_by< ordered_unique >, ordered_non_unique< composite_key< entry, member, member > > >

...

C;

I now have to swap values via the composite_key. To simplify things, I'll just express the last of three lines that would do this job if it compiles (and the lines needed to understand it).

c.get<1>().modify_key(c.get<1>().find(make_tuple(y,UINT_MAX)), ll::_1=make_tuple(y,startIter2->m_x));

This reason why this does not compile as you expect is because the key type of index #1 in your example is *not* tuple(size_t,size_t), as the code seems to be asuming. Actually, the key is an instantiation of an opaque template class called composite_key_result: http://boost.org/libs/multi_index/doc/reference/key_extraction.html#composit... As explained in the docs, there is little you can assume about this composite_key_result, except that B.MI correctly handles it internally. In particular, you cannot assign it a tuple as you're trying to do, although this operation might seem reasonable at first sight given that you can look for a tuple in a composite_key-powered index. So, instead of using modify_key resort to plain modify instead: c.get<1>().modify( c.get<1>().find(make_tuple(y,UINT_MAX)), &ll::_1->*&entry::m_x=startIter2->m_x); Is your problem solved now? Joaquín M López Muñoz Telefónica, Investigación y Desarrollo