Subject: Re: [boost] [UTF String] UTF String library 1.5 ready for perusal
From: Thomas Klimpel (Thomas.Klimpel_at_[hidden])
Date: 2011-02-16 15:35:23
Sebastian Redl wrote:
> On 11.02.2011, at 20:36, Jeffrey Lee Hellrung, Jr. wrote:
> >
> > 'Cause disallowing proxy references on random access traversal and
> > bidirectional traversal iterators...that sucks.
>
> IIRC, the issue was supposed to get addressed by the formal concepts
> for iterators. But when concepts were dropped, iterators reverted to
> their C++03 state, without any time remaining to bring in orthogonal
> iterator concepts.
If I understood Dave correctly, he is no longer convinced whether the orthogonal iterator concept would have been the correct solution.
I don't even understand the advantages of disallowing proxy references. What prevents generic code from just using
iterator_traits<Iterator>::reference when the (proxy-) reference returned from an iterator must be saved temporarily? What I can understand is to require that the iterators from the standard containers should not use proxy references, because it would force iterator_traits<iterator_type>::reference into normal non-generic user code. As many "normal" users might be not too familiar with "iterator_traits", it is desirable to avoid that situation.
However, if some algorithms of an stl implementation have difficulties with iterators returning proxy references, I think it is something that could easily be fixed if some standard would say that proxy references are allowed.
Regards,
Thomas