Re: [boost] [gil] undocumented/unintended concept requirements in color_convert

Subject: Re: [boost] [gil] undocumented/unintended concept requirements in color_convert
From: Dave Abrahams (dave_at_[hidden])
Date: 2013-03-30 23:29:20

on Sun Mar 17 2013, Michael Marcin <mike.marcin-AT-gmail.com> wrote:

> I was trying to add other color spaces support and noticed that the
> rgb to cmyk converter contains:
>
> typedef typename channel_type<P2>::type T2;
> T2 x = channel_traits<T2>::max_value()-get_color(dst,black_t());
> if (x>0.0001f) {
>     float x1 = channel_traits<T2>::max_value()/float(x);
>
> T2 should model:
> http://www.boost.org/doc/libs/1_53_0/libs/gil/doc/html/g_i_l_0264.html
>
> but this code additionally requires T2 to be greater-than comparable
> to float and convertible to float.
>

This shows that the authors of that library didn't use archetypes to
test that component.

http://www.boost.org/doc/libs/1_53_0/libs/concept_check/concept_covering.htm

-- 
Dave Abrahams