data_type_by Struct Reference

Metafunction to obtain the data type of one of the sides in a bimap. More...

Detailed Description

Metafunction to obtain the data type of one of the sides in a bimap.

The tag parameter can be either a user defined tag or member_at::{side}. This is the actual data type stored in the bimap.

template< class Tag, class Bimap >
struct data_type_by
{
    typedef typename Bimap::{side}_data_type type;
};

The following holds:

BOOST_STATIC_ASSERT
(
    is_same< data_type_by< member_at::left, bimap<A,B> >::type, A >::value
);