Extract multiple types from tuple

Question

That should be obvious, is there some short syntax to get a subtuple?

Something like that:

std::tuple<std::string, double, int> myTuple;
std::tuple<std::string, int> subTuple = std::get<std::string, int>(myTuple);

Answer 1

You need to make your own template function, this below implementation requires C++14 (because it requires std::get<T>, you can implement it in C++11 yourself):

template<typename... R, typename ...Args>
std::tuple<R...> sub_tuple(const std::tuple<Args...>& original) {
    return std::make_tuple(std::get<R>(original)...);
}

int main()
{
    std::tuple<std::string, double, int> myTuple = std::make_tuple("Hello", 1201.0, 51);
    std::tuple<std::string, int> subTuple = sub_tuple<std::string, int>(myTuple);
    std::cout << std::get<0>(subTuple) << "            " << std::get<1>(subTuple);
}

---

Note: this will create a copy for each element in the original tuple