[Boost-users] [fusion] deduce type of resulting vector from a transformation

Hi, (I keep struggling with Boos.Fusion.) How do I deduce the type of the vector resulting from the transformation of another vector? I have a source vector of different types, e.g. vectorsi::length, quantitysi::mass, quantitysi::time

and I have a transformation that is well defined and returns another type depending on the original type. The question is how do I generate a vector type that is the result of the given transformation. I though that result_of::transform was the function to obtain the result but it turns not because it returns a type transform_view instead of a vector. vector< ... > v1; T? v2(transform(v1, transformation())); i.e. what is the type of T as a fusion::vector as deduced from the type of v1 and the transformation type? -- Thank you, Alfredo-- Below is the illustrative code: #include #include #include #include #include<iostream> using std::clog; using std::endl; using namespace boost::fusion; using namespace boost::units; // this is the transformation struct divide{ template <typename SignatureT> struct result; template<class Q> struct result{ typedef typename divide_typeof_helpersi::time >::type type; }; template<typename Q> typename result::type operator()(Q const& q) const { return q/quantitysi::time(1.*si::second); } }; int main(){ typedef vector< quantitysi::length, quantitysi::mass, quantitysi::time > source_type ; source_type v1(1.*si::meter, 2.*si::kilogram, 3.*si::second); clog << "v1: " << at_c<0>(v1) << ", "<< at_c<1>(v1) << ", " << at_c<2>(v1) << endl; // how can I deduce the result_type from the type "divide"? // here manually defined typedef vector< divide_typeof_helpersi::length, quantitysi::time

::type, divide_typeof_helpersi::mass, quantitysi::time ::type, divide_typeof_helpersi::time, quantitysi::time >::type > result_type ;

result_type v2( boost::fusion::transform(v1, divide() ) ); clog << "v2: " << at_c<0>(v2) << ", "<< at_c<1>(v2) << ", " << at_c<2>(v2) << endl; return 0; }