On 3/19/2015 10:55 PM, Peter Johansson wrote:

Hi boosters,

I've been looking into the New Iterator Concepts

http://www.boost.org/doc/libs/1_57_0/libs/iterator/doc/new-iter-concepts.htm...

and then I found this comment on boost trac https://svn.boost.org/trac/boost/ticket/1296 where dave seven years ago wrote: "/the new categories are a dead-end as the standard has lifted the reference requirement on forward iterators, so I don't plan to implement anything like this. I actually plan to deprecate the new categories./"

This was seven years ago and I can't see anything about that the concepts have been deprecated, so I just wonder if this statement still holds or did the standard take back the reference requirement?

I'm looking at a recent copy of the standard (N3797), and in [forward.iterators]/1, I see:

- [...] - if `X` is a mutable iterator, `reference` is a reference to `T`; if `X` is a const iterator, `reference` is a reference to `const T`.

So I'm not sure what Dave was referring to when he said that the reference requirement on forward iterators has been dropped. FWIW, I've been working on getting the standard to *actually* drop the reference requirement, and doing it in a way that makes proxy iterators work with the standard algorithms. I've written about it here: http://ericniebler.com/2015/01/28/to-be-or-not-to-be-an-iterator/ http://ericniebler.com/2015/02/03/iterators-plus-plus-part-1/ http://ericniebler.com/2015/02/13/iterators-plus-plus-part-2/ http://ericniebler.com/2015/03/03/iterators-plus-plus-part-3/ -- Eric Niebler Boost.org http://www.boost.org