Re: [boost] [mpl::math Rational] type member

From: David Abrahams (dave_at_[hidden])
Date: 2005-10-23 09:07:50

"Andy Little" <andy_at_[hidden]> writes:

> "David Abrahams"  wrote
>> "Andy Little"  writes:
>>
>>> I am arguing for a normalised version, so for my_rational<2,8>,
>>> my_rational<3,12>  and my_rational<5,20>  among others, the normalised
>>> version
>>> is my_rational<1,4> and thats what I think rational<...>::type should return.
>>
>> Why should that normalization be done eagerly?  I can see no good
>> reason for it.
>
> Numerator and denominator members are evaluated already . I guess you could
> remove them....

I don't see what the presence of numerator and denominator has to do
with normalization.

> [cut]
>
>> Is it daft to want my_rational<x,1> to be a conforming MPL integral
>> constant?
>
> Who wants special cases? 

Who suggested a special case?

> integral constant can be converted to a
> rational constant, but not necessarily the other way. 

Don't forget that the types are all known at compile-time.  The usual
runtime logic doesn't necessarily apply.  A conversion from
my_rational<x,1> to int_<x> is not a narrowing conversion.

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