Re: [boost] [rational] Which way should std::numeric_limits::min go?

Subject: Re: [boost] [rational] Which way should std::numeric_limits::min go?
From: John Maddock (john_at_[hidden])
Date: 2013-08-22 03:18:06

> The static member function "min" has a defect.  The function "denorm_min" 
> returns the smallest positive value that can be represented (denormalized 
> or not), and is implemented only for floating types.  The function 
> "lowest," new to C++11, returns the regular (i.e. not Infinity or NaN, 
> etc.) value closest to negative-infinity.  Lowest was introduced because 
> for C++98/03, "min" returned "denorm_min" for the built-in floating types 
> and "lowest" for built-in integer types!  You can't get generic code out 
> of that (without checking some more flags from numeric_limits).
>
> Which version of "min" should boost::rational take?  I was think of 
> "denorm_min," since I'll be implementing that.  The built-in integer types 
> use "lowest" for "min," but don't define the other one at all.

I would treat it as a variant of the integer types, and set min() to the 
most negative value, and max() to the most positive value.  I suppose 
denorm_min could be the smallest positive value, but I don't think there's 
any prior art for that.

HTH, John.