On 1/22/07, Sami <randomaccessiterator@gmail.com> wrote:

Hi Tony,

Thx for your reply first of all.

On 1/22/07, Gottlob Frege < gottlobfrege@gmail.com> wrote:

On 1/22/07, Sami < randomaccessiterator@gmail.com > wrote:

Hi All,

    if (Pow == 0) return 1; // to do argue about the value of '0 to the 0'.
    if (Pow == 1) return r;
    return pow<Pow - 1>(r) * r;

}

Now, why do you want it - I doubt that it will buy you anything in terms of performance.

The issue is not particularly about performance, it is about being able to do this at compile time; other than, well, trying out MPL. Your resolution to the problem is quite nice, though that's not what I am asking. My question is about MPL, not "how to do this with C++"...

There should be a way of doing this using MPL with a single line of code. Or, even compute integer power of integers and get a compile time result. This is useful for many metaprograms and again, not a performance concern.

Any ideas?

One more note. In my original post, I mentioned this constant sequence wrapper. If there were such a thing (is there?) then one could evaluate integer power of an integer at compile time. For instance:

const unsigned SIZE = 3;

const unsigned EIGHT = fold ( constant_sequence< int_<2>, SIZE >, int_<1>, times< _ , _ > :: type :: value ;

This is only a thought. Maybe there is a better way of computing powers, without using fold or that constant_sequence thingy..

As for the real powers, maybe there is a Boost.Fusion algorithm that can do it..

sami.