Re: [Boost-users] [enable_if][type_traits] Overload resolutionquestion

From: David Abrahams (dave_at_[hidden])
Date: 2006-11-13 10:47:50

"Michael Marcin" <mmarcin_at_[hidden]> writes:

> Thank you.  It works and makes sense now because of your explanations.
> I've been working for a year now using C++ almost exclusively and there is 
> still so much left to learn *sigh*.

You're welcome.  James Dennett reminded me off-list that there's a
trick for doing power-of-2 detection: (n>0 and (n&(n-1))==0)

// something like this
template <class N>
struct is_power_of_2
  : mpl::and<
        mpl::greater<N,mpl::int_<0> >
      , mpl::equal_to<
             typename mpl::bitand<
                  N
                , typename mpl::prior<N>::type
             >::type
           , mpl::int<0>
        >
    >
{};

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com