How Can I Expand Tuples into Variadic Template Function Arguments in C ?

Expanding Tuples into Variadic Template Function Arguments

In C 17 and later, the std::apply function provides a straightforward solution to this issue. It takes a callable object and a tuple as arguments, essentially expanding the tuple into individual arguments for the function:

#include <tuple>

template<typename Tret, typename... T> Tret func(const T&... t);

int main() {
    std::tuple<int, float> my_tuple;
    auto result = std::apply(func<int, int, float>, my_tuple);
    return 0;
}

In Clang versions 3.9 onwards, std::experimental::apply can be used for similar functionality.

Handling Template Function Arguments

If the template function takes variadic template arguments, a workaround can be employed:

#include <tuple>

template<typename T> void my_func(T&& t) {}

int main() {
    std::tuple<int, float> my_tuple;
    std::apply([](auto&&... args) { my_func(args...); }, my_tuple);
    return 0;
}

This approach enables template functions to accept tuple arguments, albeit with slightly less type safety. For a more general and robust solution, refer to this resource: https://blog.tartanllama.xyz/passing-overload-sets/.

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