C++ High Performance

Unrolling the tuple

As tuples cannot be iterated as usual, what we need to do is to use metaprogramming to unroll the loop. From the previous example, we want the compiler to generate something like this:

auto tpl = std::make_tuple(1, true, std::string{"Jedi"}); 
std::cout << std::get<0>(tpl) << " "; 
std::cout << std::get<1>(tpl) << " "; 
std::cout << std::get<2>(tpl) << " "; 
// Prints "1 true Jedi" 

As you can see, we iterate every index of the tuple, and therefore, we need the number of types/values contained in the tuple. Then, as the tuple contains different types, we need to write a metafunction that generates a new function for every type in the tuple.

If we start with a function that generates the call for a specific index, it will look ...