On Mon, May 10, 2010 at 2:24 PM, Mathias Gaunard <mathias.gaunard@ens-lyon.org> wrote:

Neil Groves wrote:

This can't easily be remedied since the Range Concept is non-copyable, and we obviously can't pass a const reference as the target to the fill algorithm. Making the Range Concept cheaply copyable would mean that the standard containers were no longer a model of the Range Concepts. I am currently investigating extending the sub_range

It should be perfectly ok to make iterator_range and sub_range cheaply copyable, since they just wrap iterators.
No need to extend the range concepts for that; iterator_range would simply provide more than those concepts.

The rationale for providing new concepts that extend the sub_range is that we can then implement new containers and new algorithms in terms of concepts similar to those that Alexandrescu describes.

As you have suggested this is actually a very simple extension to sub-range and allows efficient interoperability between iterator ranges and Alexandrescu style ranges. I'm finding this to be very nice when implementing ranges that do not map well to iterators, such as an unbounded integer range.

I'm in the very early stages of exploring these ideas.

Regards,

Neil Groves