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

From: Joel de Guzman (joel_at_[hidden])
Date: 2007-03-19 20:46:39

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<S, K>::type
result_of::value_at_key<S, K>::type

??

Regards,
-- 
Joel de Guzman
http://www.boost-consulting.com
http://spirit.sf.net