On 5/23/06, Shunsuke Sogame <mb2act@yahoo.co.jp> wrote:
Daniel Walker wrote:
On 5/23/06, Shunsuke Sogame <mb2act@yahoo.co.jp> wrote:
BTW, I found a bug: <boost/range/concepts.hpp> seems to apply 'boost::size' to Forward Range.
If I recall correctly applying boost::size() was intentional. size(r) is a valid expression for the ForwardRange concept, and I believe Thorsten didn't want ADL to kick in, so in the concept check implementation boost:: is used to qualify all the functions. boost::size() eventually dispatches either a size() member of the range object or std::distance().
Updated cvs shows 'boost::size' uses 'operator-' ? I somewhat wonder why 'boost::size' and 'boost::range_size' are not deprecated like 'boost::range_result_iterator'.
My bad. I just got the new range files (very busy the last few weeks) and there is a bug here. Actually, I think this is a case of the concept checks reveling a bug in the library. The following generates the error you're seeing. #include <boost/concept_check.hpp> #include <boost/iterator/iterator_archetypes.hpp> #include <boost/range/concepts.hpp> #include <boost/range/iterator_range.hpp> using namespace boost; using namespace std; int main() { typedef iterator_archetype< int, iterator_archetypes::readable_iterator_t, forward_traversal_tag > iterator_type; typedef iterator_range<iterator_type> range_type; function_requires<ForwardRangeConcept<range_type> >(); } The problem is that the ForwardRange concept requires the expression size(r) where r is an object of type X modeling ForwardRange and boost::range_iterator<X>::type is a model of ForwardTraversalIterator. However, the implementation of boost::size(r) expects X to provide operator-, which is an expression of RandomAccessTraversalIterator. So, I think either size(r) should be removed from the FowardRange concept (bad idea), or boost::size(r) should either offer a specialization for ForwardRanges or revert to dispatching the call to std::distance() (better idea?). Daniel