Den 02-02-2012 03:00, Dave Abrahams skrev:
on Wed Feb 01 2012, Mathias Gaunard<mathias.gaunard-AT-ens-lyon.org> wrote:
They are in Boost, and in particular in Boost.Range, which was being asked about here.
I understand. Maybe Beman didn't know that Boost.Range ranges were iterator pairs. In the end,
We're explicitly interested in what happens to efficiency when algorithms are /implemented/ using range primitives rather than by iterator increment, comparison, etc.
Well, the only way to answer that is by implementing Alexandrescu's range abstractions and start comparing it with BoostRange. Not trivial IMO. Then make sure that the underlyigng algorithms/loop-unrolling are exactly the same. So basically, a huge (but very interesting) work. An advantage of range primitives is whever we need to store a predicate or functor; in Boost.Range, we need to store one in each iterator which is not optimal (clever implementation of transform_iterator/filter_iterator would optimize this away for empty functors/predicates). Again, I don't know what the speed difference will be between the two ideas; If the data being processed is large, I guess storing an extra function in the end iterator is of no significance. The iterator-based range library also seem to work well with the existing standard library; -Thorsten