#include <boost/mpl/map.hpp>

#include <iostream>

#include <boost/mpl/at.hpp>

#include <boost/mpl/placeholders.hpp>

#include <boost/mpl/for_each.hpp>

typedef boost::mpl::map<

            boost::mpl::pair<

                        boost::mpl::int_<0>,

                        boost::mpl::int_<3>

            >,

            boost::mpl::pair<

                        boost::mpl::int_<1>,

                        boost::mpl::int_<2>

            >,

            boost::mpl::pair<

                        boost::mpl::int_<2>,

                        boost::mpl::int_<1>

            >,

            boost::mpl::pair<

                        boost::mpl::int_<3>,

                        boost::mpl::int_<0>

            >

> CMapForward;

typedef boost::mpl::map<

            boost::mpl::pair<

                        boost::mpl::int_<0>,

                        boost::mpl::int_<3>

            >,

            boost::mpl::pair<

                        boost::mpl::int_<1>,

                        boost::mpl::int_<2>

            >,

            boost::mpl::pair<

                        boost::mpl::int_<2>,

                        boost::mpl::int_<1>

            >,

            boost::mpl::pair<

                        boost::mpl::int_<3>,

                        boost::mpl::int_<0>

            >

> CMapReverse;

template<typename I2E_PAIR, typename E2I>

struct CCreatePair:boost::mpl::pair<typename I2E_PAIR::first, boost::mpl::at<E2I, typename I2E_PAIR::second> >

{          

};

struct CDoSomething

{           template<unsigned int INDEX0, unsigned int INDEX1>

            inline void operator()(const boost::mpl::pair<boost::mpl::int_<INDEX0>, boost::mpl::int_<INDEX1> > &_r) const

            {           std::cout << INDEX0 << " " << INDEX1 << "\n";

            }

};

int main(int, char**)

{           boost::mpl::for_each<

                        CMapForward,

                        template CCreatePair<boost::mpl::_1, CMapReverse>

            >(CDoSomething());

            return 0;

}

"The first point (using an init() function in preference to a constructor) is bogus. Using constructors and exception handling is a more general and systematic way of dealing with resource acquisition and initialization errors. This style is a relic of pre-exception C++." -- Stroustrup