[boost] [mpl] rational_c, fraction_c

From: Andy Little (andy_at_[hidden])
Date: 2005-02-28 06:51:23

Hi All,

     What is the current status of compile time fractions / rationals?

    Various directions are

   1 Alexei Gurovois in boost/mpl/math/rational_c.hpp

    2  Cromwell Enages work on the files section
    <http://groups.yahoo.com/group/boost/files/mpl_math.zip>

   3  Hugo Duncans:
    http://tinyurl.com/2qrpq
    However the three are not compatible with each other

    In Cromwells (named fraction_c) and Hugo Duncans the numerator and 
denominator are mpl Integral Constants not values, as in Alexeis original.

                    mpl::rational_c<int,1,2>::denominator;   //  == 2
                    against
                    mpl::rational_c<int,1,2>::denominator::value; == 2

    Cromwell's version is not a nullary_metafunction whereas Hugo Duncans 
and Alexeis are. This is the right thing IMO because the type can be reduced
    eg  2/2 ---> 1,
Also see

http://lists.boost.org/MailArchives/boost-users/msg06245.php

I appreciate that there my be advantages to Cromwells and Hugo Duncans 
versions.. Ultimately  either the version in the release should be removed/ 
modified or 'lived with'.

Anyone have  any thoughts. And is anyone still working on this?

regards
Andy Little