Re: [boost] [constrained_value] Formal review request

From: Robert Kawulak (kawulak_at_[hidden])
Date: 2008-07-10 19:25:46

Hi,

> From: Joe Gottman
> 
> Robert Kawulak wrote:
> > Hi,
> > 
> >> From: utku
> >>
> >> can we create a saturating int with only lower bound set and 
> >> upper bound is infinite, like
> >>
> >>   saturating_int<int, 1>::type ImageBoundary;
> > 
> > Yes, you can simply write:
> > 
> > saturating_int<int, 1, boost::integer_traits<int>::const_max>::type
> > ImageBoundary;
> > 
> > Since no int is greater than const_max, the upper bound 
> will never be used for
> > saturation (and I bet compilers will easily optimise the 
> code eliminating the
> > comparison with the upper bound).
> 
>     Would it be possible for you to make that a default parameter for 
> the  class?  That would really improve usability for this use-case.

I don't know if it's a good idea to make the default for this special use case -
if I'd see something like saturating_int<int, 1>::type, probably it wouldn't be
easy for me to guess if it saturates below or over 1. Maybe another set of
aliases with more descriptive names would be better? Like:

lower_saturating_int<int, 0>::type - clips values less than 0
upper_saturating_int<int, 0>::type - clips values greater than 0

I'm not sure if those names are good enough either... BTW, is this a common use
case in some areas?

Best regards,
Robert