Re: [boost] [range] How to extend Boost.Range?

From: Eric Niebler (eric_at_[hidden])
Date: 2005-09-01 08:09:00

Pavol Droba wrote:
> 
> It might a problem with documentation, but it seems that you have misunderstood
> the basic idea of the Range library.

There is a section in the documentation entitled "Extending the Library" 
that doesn't describe how to extend the library. I'd say that's a pretty 
serious problem in the documentation.

> 
> Core of the range library is not in the code, rather in concepts that are defined
> there. 
> 
> http://boost.org/libs/range/doc/range.html
> 

In that case, the Range library and the concepts it defines are 
fundamentally broken. It seems to be requiring that everybody at all 
times make qualified calls to boost::begin() and boost::end(). 
Therefore, in order to extend the library, users must put *their* 
begin() and end() functions in the boost namespace. This is distasteful, 
but I'll let that slide.

The more serious problem is the way this interacts with 2-phase lookup. 
Since it is a qualified call, any call to boost::begin() from within a 
template will get resolved during the first lookup phase. If a user's 
overload has not been seen yet, it will not get considered.

So, is Boost.Range broken, or is this another problem with the 
documentation?

-- 
Eric Niebler
Boost Consulting
www.boost-consulting.com