Jeffrey Hellrung wrote:
Without being an expert, a quick review of
http://www.boost.org/doc/libs/1_42_0/libs/iterator/doc/iterator_facade. html#iterator-category
shows that std::output_iterator_tag is never chosen as the iterator category by boost::iterator_facade. It also shows that the behavior of choosing std::input_iterator_tag for your particular case is the documented behavior.
Thanks, so at least I know now that I didn't misinterpreted the code in "facade_iterator_category.hpp". I fact, the documentation in "facade_iterator_category.hpp" itself was less clear with respect to this questions, so that I already wondered whether I had missed something in boost::multi_array causing the iterator not to be an output_iterator. excerp from "facade_iterator_category.hpp": // // Convert an iterator_facade's traversal category, Value parameter, // and ::reference type to an appropriate old-style category. // // If writability has been disabled per the above metafunction, the // result will not be convertible to output_iterator_tag. // // Otherwise, if Traversal == single_pass_traversal_tag, the following // conditions will result in a tag that is convertible both to // input_iterator_tag and output_iterator_tag: // // 1. Reference is a reference to non-const // 2. Reference is not a reference and is convertible to Value // template <class Traversal, class ValueParam, class Reference> struct iterator_facade_default_category Regards, Thomas