I started porting over some old codes that used hand-made MPL<->concrete object code to Fusion. I'm currently trying to have the following to work with no results so far : struct make_arg { template<class Type> struct result { typedef typename boost::add_reference<typename boost::add_const<Type>::type >::type type; }; }; template<class Args> struct tree { typedef Args children; typedef typename bf::result_of::transform<Args,make_arg>::type contents; template<class T0,class T1> tree( const T0& t0 , const T1& t1 ) : mArgs( /* what to put here ??? */ ) {} template<size_t I> typename bf::result_of::at_c<contents,I>::type get() const { return bf::at_c<I>(mArgs); } contents mArgs; }; int main() { int k=3; float u=7.2; tree< bf::vector<int, float> > tree(k,u); return 0; } The question - as stated - in the code is how to simply build the mArgs member from the t0,...,tn arguments ? Thanks in advance. -- Joel FALCOU Research Engineer @ Institut d'Electronique Fondamentale Université PARIS SUD XI France