Re: [boost] Promote Traits -- Review of Generic Image Library (GIL)

From: Ullrich Koethe (koethe_at_[hidden])
Date: 2006-10-17 17:23:16

Hi David,

David Greene wrote:
>Because that's what the C++ standard says (AFAIR).
> 
> 
> But the standard isn't always the best answer for all promotion
> situations.  For example, some years back I wrote some expression
> template code for simulation purposes.  I wanted a simple user
> interface so I promoted int / int to double to avoid loss of
> precision.
> 

Right. So VIGRA supports two promotions standard Promote (what the 
compiler does by default) and RealPromote (the floating point promotion is 
guaruanteed)

> Stuffed away in some cobweb-infested dusty disk sector I have a
> library that implements promotion "strategies" using a table-driven
> configuration of (operator/operand type -> promotion type) rules.

That's how VIGRA's promotion traits essentially work.

> I'll see if I can dig it out and post it as a starting point.  I'm
> not sure if it's what we want as a Boost library but it might be a
> start for discussion.

Will be interesting to look at.

Regards
Ulli

-- 
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| Ullrich Koethe  Universitaet Hamburg / University of Hamburg   |
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