Re: [boost] [iterator] counting_iterator and reverse iterator problem (was: [graph][iterators] csr graph and reverse iterator problem)

Subject: Re: [boost] [iterator] counting_iterator and reverse iterator problem (was: [graph][iterators] csr graph and reverse iterator problem)
From: Jeremiah Willcock (jewillco_at_[hidden])
Date: 2011-09-08 14:31:10

On Thu, 8 Sep 2011, Takatoshi Kondo wrote:

> Hi,
>
> On Thu, 8 Sep 2011 07:48:01 +0900
> Michel Morin <mimomorin_at_[hidden]> wrote:
>
>> Relevant ticket (#2640):
>>   https://svn.boost.org/trac/boost/ticket/2640
>>   Legal forward iterators cannot store their referents
>>   (was: counting_iterator::reference lifetime tied to iterator)
>
> Thanks, I've understood what is the problem.
> I think that when we write a generic algrithm using reverse_iterator
> or make own iterator using counting_iterator, we should refer to this
> problem in comment.
>
> Anyway my problem has solved. Thanks again :)

One further note -- there is nothing in the BGL requirements that states 
that vertex_iterators need to be bidirectional, so you cannot rely on that 
being true for arbitrary graph types (see 
http://www.boost.org/doc/libs/1_47_0/libs/graph/doc/VertexListGraph.html).

-- Jeremiah Willcock