Feed template function element from tuple at runtime?

Question

In C++ I have a tuple with some elements in it:

std::tuple  my_tuple(3, \'q\');

And some template function that perfectly

Answer 1

Following may help:

template  struct caller;

template  struct caller>
{
    template 
    void operator() (F f, std::tuple& t, int n)
    {
        (*this)(f, t, n, std::index_sequence_for());
    }
private:
    template 
    void operator() (F f, std::tuple& t, int n, std::index_sequence)
    {
        std::function&)> fs[] = { &helper... };
        fs[n](f, t);
    }

    template 
    static void helper(F f, std::tuple& t)
    {
        f(std::get(t));
    }

};

template 
void call(F f, T& t, int n)
{
    caller()(f, t, n);
}

Live example