The following code example is taken from the book
C++ Templates - The Complete Guide, 2nd Edition
by David Vandevoorde, Nicolai M. Josuttis, and Douglas Gregor,
Addison-Wesley, 2017
© Copyright David Vandevoorde, Nicolai M. Josuttis, Douglas Gregor 2017
// recursive case:
template<unsigned N>
struct TupleGet {
template<typename Head, typename... Tail>
static auto apply(Tuple<Head, Tail...> const& t) {
return TupleGet<N-1>::apply(t.getTail());
}
};
// basis case:
template<>
struct TupleGet<0> {
template<typename Head, typename... Tail>
static Head const& apply(Tuple<Head, Tail...> const& t) {
return t.getHead();
}
};
template<unsigned N, typename... Types>
auto get(Tuple<Types...> const& t) {
return TupleGet<N>::apply(t);
}