Re: [Boost-users] [Concept] boost::FloatingPoint<T>

Subject: Re: [Boost-users] [Concept] boost::FloatingPoint<T>
From: Dave Abrahams (dave_at_[hidden])
Date: 2010-09-18 09:07:21

On Wed, Sep 15, 2010 at 2:02 PM, Ruediger Berlich
<ruediger.berlich_at_[hidden]> wrote:
> Hi there,
>
> I'd like to make sure that some of my classes are only used with particular
> value types. This is easy enough to implement for integers, using
> BOOST_CONCEPT_ASSERT((boost::Integer<T>)) . However, there is no
> boost::FloatingPoint<T>, which is a bit odd.
>
> The following, easy code seems to do what I want, but reqires inclusion of
> boost/concept/detail/concept_def.hpp
>
> /*****************************************************************/
>
> namespace boost
> {
>  BOOST_concept(FloatingPoint, (T))
>
> >From what I understand, this means that I am relying on implementation
> details with the above code.

Yes.  Why did you use the undocumente BOOST_concept macro?  That only
exists for backward compatibility with older uses of the BCCL.

> Is there any way to do the above in a portable way?

 // untested
 #include <boost/type_traits/is_floating.hpp>
 #include <boost/mpl/assert.hpp>

 template <class T> struct FloatingPoint
 {
     BOOST_MPL_ASSERT((boost::is_floating<T>));
 };

> P.S.: If the above seems acceptable, please feel free to include it in
> Boost.Concept.

If what I suggested works out for you, would you mind submitting a
patch to Trac?

-- 
Dave Abrahams
BoostPro Computing
http://www.boostpro.com