On Wed, Oct 13, 2010 at 2:45 PM, David Abrahams <dave@boostpro.com> wrote:
At Wed, 13 Oct 2010 17:09:38 +0100,
[snip]
Segmented iterators are neither practical to write nor to use. ou've
Why do you say that? I don't think anyone has made a serious effort.
I've been watching this thread and I've been thinking of saying my experience trying to use segmented iterators. I am working on a project that has a hierarchical structure where an object can own other objects of the same type. It is a tree-structure. This hierarchical structure might be acessible hierachically or not. Conceptually it always is, but it might be accessible only through input_iterators which would flatinize the hierarchy in a efficient way. But, some other implementation might be able to access it hierarchically, which would allow some algorithms, e.g. find, to work in better-than-a-linear time. At first I thought that segmented iterators were what I needed. But then trying to work with it. I found that segmented iterators would differentiate segment iterators from local iterators in a way that didn't work in a tree-like structure. The nodes of the trees had to be moved to be the first in the local sequence because only local iterators are dereferenced in segmented-aware algorithms. This meant that segmented iterators weren't completely overhead-free. This doesn't mean segmented iterators aren't good, just that the use-case that I tried didn't seem to fit it. [snip]
-- Dave Abrahams BoostPro Computing http://www.boostpro.com
Regards, -- Felipe Magno de Almeida