get part of std::tuple

Question

I have a tuple of unknown size (it\'s template parametr of method)

Is it way to get part of it (I need throw away first element of it)

For example, I have

Answer 1

There may be an easier way, but this is a start. The "tail" function template returns a copied tuple with all values of the original except the first. This compiles with GCC 4.6.2 in C++0x-mode.

template<size_t I>
struct assign {
  template<class ResultTuple, class SrcTuple>
  static void x(ResultTuple& t, const SrcTuple& tup) {
    std::get<I - 1>(t) = std::get<I>(tup);
    assign<I - 1>::x(t, tup);
  }
};

template<>
struct assign<1> {
  template<class ResultTuple, class SrcTuple>
  static void x(ResultTuple& t, const SrcTuple& tup) {
    std::get<0>(t) = std::get<1>(tup);
  }
};


template<class Tup> struct tail_helper;

template<class Head, class... Tail>
struct tail_helper<std::tuple<Head, Tail...>> {
  typedef typename std::tuple<Tail...> type;
  static type tail(const std::tuple<Head, Tail...>& tup) {
    type t;
    assign<std::tuple_size<type>::value>::x(t, tup);
    return t;
  }
};

template<class Tup>
typename tail_helper<Tup>::type tail(const Tup& tup) {
  return tail_helper<Tup>::tail(tup);
}