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So I have some type X : typedef ... X; and a template function f : class <typename T> void f(X& x_out, const T& arg_in); and then a function g : void g(const X* x_array, size_t x_array_size); I need to write a variadic template function h that does this: template<typename... Args> void h(Args... args) { constexpr size_t nargs = sizeof...(args); // get number of args X x_array[nargs]; // create X array of that size for (int i = 0; i < nargs; i++) // foreach arg f(x_array[i], args[i]); // call f (doesn't work) g(x_array, nargs); // call g with x_array } The reason it doesn't work is because you can't subscript args like that at runtime. What is the best technique to replace the middle part of h ? And the winner is Xeo: template<class T> X fv(const T& t) { X x; f(x,t); return x; } template<class... Args> void h(Args... args) { X x_array[] = { fv(args)... }; g(x_array, sizeof...(Args)); } (Actually in my specific case I can rewrite f to return x by value rather than as an out parameter, so I don't even need fv above)

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