dispatcher

#include <iostream>

template<int N>
void foo() { std::cout << __PRETTY_FUNCTION__ << '\n'; }

template <int... Ns>
decltype(auto) dispatch_foo(int const n, std::integer_sequence<int, Ns...>) {
    static constexpr void (*_foos[])() { &foo<Ns>... };
    return _foos[n]();
}

template <int Nmax>
decltype(auto) dispatch_foo(int const n) {
    return dispatch_foo(n, std::make_integer_sequence<int, Nmax>{});
}

int main() {
    dispatch_foo<10>(3);
}