Re: [Boost-users] [mpl][fusion] Metafunction for extracting a type from a map

Christian Henning wrote:

Sorry for my bad problem description. Basically I have a map of type vectors. On element in the vector is used for tagging. I need a metafunction that can retrieve the type vector that that's is tagged with the _primary_key_ type. There is only one vector. I would also need the same functionality for the _foreign_key_ type. Here, it can be several type vectors.

The MPL lib has a find_if metafunction that looks like the right way to do. But I haven't tried it yet.

Is this description better?

Have you tried (either): result_of::at_key::type result_of::value_at_key::type ?? Regards, -- Joel de Guzman http://www.boost-consulting.com http://spirit.sf.net