A workaround for partial specialization of function template?

Question

Consider the following metafunction for an integral pow (it is just an example) :

class Meta
{
    template static constexpr T ipow(         


        

Answer 1

Anytime you ask yourself "how to simulate partial specialization for functions", you can think "overload, and let partial ordering decide what overload is more specialized".

template
using int_ = std::integral_constant;

class Meta
{
    template static constexpr T ipow(T x)
    {
        return ipow(x, int_<(N < 0) ? -1 : N>());
    }

    template static constexpr T ipow(T x, int_<-1>)
    {
        //                             (-N) ??
        return static_cast(1) / ipow<-N>(x, int_<-N>());
    }

    template static constexpr T ipow(T x, int_)
    {
        return x * ipow(x, int_());
    }

    template static constexpr T ipow(T x, int_<0>)
    {
        return 1;
    }
};

I think you wanted to pass -N instead of N at the comment-marked position.