Remove algorithms implementation duplications

[Marc Glisse]

On Wed, 11 Jul 2012, François Dumont wrote:

>    Here is the new patch based on Marc Glisse idea to use functors taking 
> iterators rather than iterators::reference. Compare to the previous proposal 
> there is no more impact on the creation of temporaries instances, no 
> additional copy or move constructor. Of course there are additional iterators 
> or functors copies but those types are supposed to be lightweight types easy 
> to copy.

I may have shot myself in the foot with that one ;-) (I sometimes have 
heavy iterators and functors, but that's my problem).

I can't review the patch, but I have a question, if you have time: what is 
your personal feeling on which approach is simpler, which yields the 
cleanest code, which is more flexible? Or are they all roughly the same?
You spent quite a bit of time implementing several versions of this patch, 
and I would be happy to learn from your experience.

-- 
Marc Glisse