Re: [boost] Iterator facade < operation?

From: David Abrahams (dave_at_[hidden])
Date: 2006-06-29 15:45:17

Geoff Wedig <wedig_at_[hidden]> writes:

> I have a question I'm hoping someone can answer.  I've recently started 
> using the iterator_facade class, and it's very useful, but it seems 
> inefficient in some respects.  Specifically, the < operator.  According 
> to the website docs, this uses the distance_to() function defined by the 
> derived class.  That works fine for some iterators, but not others. 
> Often, it's possible to have much more efficient operations than that. 
> Take for example, some data structure of sorted strings.  It is not 
> necessary to know how many elements are between two strings to know 
> whether one is before the other.  Like 'use empty() rather than size() 
> == 0' in Meyer's _Effective STL_, it would seem that a more efficient 
> solution can be created in many cases.
>
> So, is there a way to do this, to override iterator_facade's system, or 
> am I missing something?  

Sure, just add your own operators that match better than the generic
ones provided by the library.

-- 
Dave Abrahams
Boost Consulting
www.boost-consulting.com