From: Arash Partow (arash_at_[hidden])
Date: 2008-03-28 09:04:35
John Femiani wrote:
> This is why I would like to see concepts spelled out like this:
> http://www.boost.org/libs/concept_check/reference.htm#basic-concepts
> as is done by other boost libraries which I like, such as gil
> http://stlab.adobe.com/gil/html/index.html, BGL
> http://www.boost.org/libs/graph/doc/graph_concepts.html , fusion, and
> others. They all clearly specify their concepts using the SGI style and
> provide concept checking classes. To me that makes them easy to
> understand.
>
> IMHO the core need from a point library is the concepts, not the models,
> because there are so many different well-tuned geometry libraries that
> exist, and the idea is that boost _algorithms_ work on any "point",
> rather than that boost have a great point class (those are easy).
>
The questions here is should the concept(s) spell out each and every
property of the object (point for example)? In the on going example
of the distance routine, say I provide a point that is comprised of
my_rational type. but I have not defined a sqrt function for it, should
say stuff like that be definable as concept as well - if so where do we
stop?
> Also, I already disagree about the idea that a point should have
> coordinates.
I agree
> CoordinatesConcept should be part of a separate concept. Of
> course a useful point class will model both the coordinates and the
> point concept. To me a point should really support transform, scale,
> rotate, shear, and distance operations as free functions (maybe more).
>
> I don't know how to handle the idea of a 'space' or a 'kernel'.
Well they occur(are needed) when you want to re/define various operators
or truths. It would be go to somehow link type,object,routine and space
together - with obvious/common defaults provided by the library.
Arash Partow
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