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

A tuple slice operation (that also works for std::array and std::pair) can be defined like this (C++14 required):

namespace detail
{
    template 
    constexpr auto slice_impl(Tuple&& t, std::index_sequence)
    {
        return std::forward_as_tuple(
            std::get(std::forward(t))...);
    }
}

template 
constexpr auto tuple_slice(Cont&& t)
{
    static_assert(I2 >= I1, "invalid slice");
    static_assert(std::tuple_size>::value >= I2, 
        "slice index out of bounds");

    return detail::slice_impl(std::forward(t),
        std::make_index_sequence{});
}

And an arbitrary subset of a tuple t can be obtained like so :

tuple_slice(t); 

Where [I1, I2) is the exclusive range of the subset and the return value is a tuple of either references or values depending on whether the input tuple is an lvalue or an rvalue respectively (a thorough elaboration can be found in my blog).