C++11 way to index tuple at runtime without using switch

Question

I have a piece of c++11 code similar like below:

switch(var) {
   case 1: dosomething(std::get<1>(tuple));
   case 2: dosomething(std::get<2>(tup         


        

Answer 1

No need to get all cray cray in c++17.

template 
inline void runtime_get(Func func, Tuple& tup, size_t idx) {
    if (N == idx) {
        std::invoke(func, std::get(tup));
        return;
    }

    if constexpr (N + 1 < std::tuple_size_v) {
        return runtime_get(func, tup, idx);
    }
}

And runtime tuple_element for fun.

// Returns a pointer to the type, so the element is not initialized.
template 
inline void runtime_tuple_element(Func func, size_t idx) {
    if (N == idx) {
        std::tuple_element_t* ptr = nullptr;
        std::invoke(func, ptr);
        return;
    }

    if constexpr (N + 1 < std::tuple_size_v) {
        return runtime_tuple_element(func, idx);
    }
}