So far, this is all I've been able to come up with:

#include <boost/mpl/map.hpp>
#include <boost/mpl/at.hpp>

namespace detail
{
    template< unsigned int t_value >
    struct integral
    {
        static const unsigned int value = t_value;
    };

    typedef boost::mpl::map<    boost::mpl::pair<float, integral<GL_FLOAT> >,
                                boost::mpl::pair<double, integral<GL_DOUBLE> >
                            > glTypeMap;
};

template< typename t_type >
struct Vertex
{
    static const unsigned int type = boost::mpl::at<detail::glTypeMap, t_type>::type::value;
    t_type x, y, z;
};

On Nov 16, 2007 5:48 PM, Robert Dailey < rcdailey@gmail.com> wrote:
Hi,

I'm looking for a complete compile-time constant map container that uses types as keys and integral constants as values. For example:

typedef map< pair<float, 90>, pair<unsigned int, 3> > mapType;
unsigned int value = get_value<mapType, float>::value;

The above code is PSEUDO CODE only. It is supposed to give you an idea of what I'm looking for. I tried using boost::fusion::map, however the fusion::pair object expects a TYPE as the second template argument, so I can't specify integral values. Could someone provide a code example that achieves the above? Note that I should be able to do the following as well:

typedef map<  pair<float, 90>,
              pair<unsigned int, 3>
              > mapType;

class foo
{
    // This would result in 'value' being the integral number 90.
    static const unsigned int value = get_value<mapType, float>::value;
}