How to construct a tuple from an array

Question

I am designing a C++ library that reads a CSV file of reported data from some experiment and does some aggregation and outputs a pgfplots code. I want to make the library as

Answer 1

As with all questions involving std::tuple, use index_sequence to give you a parameter pack to index the array with:

template <class... Formats, size_t N, size_t... Is>
std::tuple<Formats...> as_tuple(std::array<char*, N> const& arr,
                                std::index_sequence<Is...>)
{
    return std::make_tuple(Formats{arr[Is]}...);
}

template <class... Formats, size_t N,
          class = std::enable_if_t<(N == sizeof...(Formats))>>
std::tuple<Formats...> as_tuple(std::array<char*, N> const& arr)
{
    return as_tuple<Formats...>(arr, std::make_index_sequence<N>{});
}

Which you would use as:

std::tuple<Format...> the_line = as_tuple<Format...>(toks);