At Tue, 28 Sep 2010 19:05:00 +0200, Andrzej Krzemienski wrote:
Well, I believe I got it wrong. It is concept maps where the specializtion is to tke plce. It should read:
explicit concept< typename T > IntOrPair
"explicit concepts" were never part of any accepted proposal ;-)
{ int sum_ints_impl( T const& ); }
concept_map IntOrPair<int> { int sum_ints_impl( int const& i ) { return i; } }
template< IntOrPair type1, IntOrPair type2 > concept_map IntOrPair< std::pair<type1, type2> > { int sum_ints_impl( std::pair<First, Second> const& p ) { return sum_ints_impl(p.first) + sum_ints_impl(p.second); } }
template<IntOrPair T> int sum_ints( T const & t ) { return IntOrPair::sum_ints_impl( t ); }
I think what you wrote is equivalent to what I posted in http://permalink.gmane.org/gmane.comp.lib.boost.devel/209012 However, as I noted in that message, trying to constrain something to be either an Int or a Pair is really against the spirit of GP. -- Dave Abrahams BoostPro Computing http://www.boostpro.com