I should have said "for counting_iterator<int> or some other fundamental type", by calculating with the bounds.
Maybe so, but I'm obviously missing something, because I still can't guess what you have in mind.
counting_iterator<int> lower_bound( counting_iterator<int> begin, counting_iterator<int> end, int n ) { if( n<begin ) return begin; else if( n<end ) return counting_iterator<int>(n); else return end; }
To get a bit more specific, are you suggesting introducing a boost::lower_bound? Do you want it to always forward to boost::partition_point? Or should it by default forward to std::lower_bound, and only be overloaded for those specific iterators for which a custom boost::partition_point is implemented?
My current thinking is: boost::lower_bound -> partition_point (via ADL) -> std::lower_bound (by default) Make sense?
Do you mean this? namespace boost { template< ... > It lower_bound( It begin, It end, T value ) { using boost::partition_point; return partition_point( begin, end, boost::bind( ... ) ); } template< ... > It partition_point( It begin, It end, Pred pred ) { return std::lower_bound( begin, end, boost::bind( ... ) ); } // a custom implementation of partition_point: template< ... > transform_iterator<It,Func> partition_point(transform_iterator<It,Func> begin, transform_iterator<It,Func> end, Pred pred ) { ... } ... more custom implementations ... } Is implementing partition_point by std::lower_bound possible? I remember seeing a paper of yours that pointed out that in template< class It, class T, class Pred ) lower_bound( It begin, It end, T value, Pred pred ) T must be It::value_type. Then, how do you do the forwarding? Instead, I suggest providing our own implementation of partition_point.
I think we agree that we must introduce a default boost::partition_point. How should the customization happen there? Via ADL on partition_point, or again via overloading boost::partition_point?
Inviting users to overload in your namespace is simply not a viable customization approach in general, so ADL is it.
O.k., agreed. Why do you think ADL is o.k. for customizing boost::partition_point (soon std::partition_point, N2666), but not for customizing std::lower_bound? AFAIK, the same arguments apply to both. Arno -- Dr. Arno Schoedl · aschoedl@think-cell.com Technical Director think-cell Software GmbH · Invalidenstr. 34 · 10115 Berlin, Germany http://www.think-cell.com · phone +49-30-666473-10 · toll-free (US) +1-800-891-8091 Directors: Dr. Markus Hannebauer, Dr. Arno Schoedl · Amtsgericht Charlottenburg, HRB 85229