Re: [boost] [iterator] Combining traversal_tags with iterator_tags

Subject: Re: [boost] [iterator] Combining traversal_tags with iterator_tags
From: Ronald Garcia (rxg_at_[hidden])
Date: 2012-01-08 11:07:44

Hi Dave,

On Jan 7, 2012, at 4:56 PM, Dave Abrahams wrote:

>> So it looks like passing:
>> boost::detail::iterator_category_with_traversal<boost::detail::input_output_iterator_tag,boost::random_traversal_tag>
>> 
>> as the CategoryOrTraversal would be what I want.  However, two
>> components above are in the detail namespace, so I am not sure if they
>> are meant to be used by other libraries.  Is this a safe operation?
> 
> Using things in detail namespaces is never really "safe" unless you own
> the surrounding namespace.

Definitely.  Let me rephrase then:  it seems as though these two items, input_output_iterator_tag and iterator_category_with_traversal, could be elevated out of boost::detail and be part of the public interface of the iterator library.  As far as I can tell, neither is ever used in the implementation of  the library, which makes them currently dead code.  However, I don't know enough about the iterator library to know if this makes sense.  So:  does it make sense for these two classes to appear as part of the iterator library interface, or are there some aspects of the library design or existing interface that would preclude this?  If there is no such problem, then I would be happy to file a feature request via Trac, and possibly even propose some patches to make it so.  

Best,
Ron