Re: [Boost-users] [fusion] how to get the tuple of min values of 2 tuples whatever their length?

On 7/17/2013 7:17 AM, Frédéric Bron wrote:

I have two tuples: typedef boost::tuple Key; Key k1, k2;

I would like to get the tuple of the min values for each corresponding value between k1 and k2: Key min=Key(std::min(k1.get<0>(), k2.get<0>()), std::min(k1.get<1>(), k2.get<1>()), std::min(k1.get<2>(), k2.get<2>()));

but I do not know the length of the tuple so I am looking for a generic algorithm... Is this possible with boost::fusion or boost::mpl?

I have tried with boost::fusion::accumulate but I need to now in the functor the index of the value that is currently accessed to compare to the right one in k1.

Have you tried the binary version of fusion::transform described at: http://www.boost.org/doc/libs/1_54_0/libs/fusion/doc/html/fusion/algorithm/t... You'll need a polymorphic function object wrapping std::min(unless fusion has an adapter), something like(untested): struct PolyMin { template<typename T> struct result { typedef typename boost::remove_const< typename boost::remove_reference<T>::type>::type type; }; template<typename T> T operator()(const T& lhs, const T& rhs) const { return (std::min)(lhs, rhs); } }; Jeff