you can easily achieve this using (make_)transform_iterator and boost bind: make_transform_iterator( map.begin(), boost::bind( &MAP_TYPE::value_type::first, _1 ) ) (give or take a typename before MAP_TYPE::...) I think it's so simple that you don't really need a utility class for it. I'm also quite sure that boost bind takes better care of const/mutable return type and any other bad things that you may stumble across when trying to implement this functor youself (same goes for boost.lambda). eyal. -----Original Message----- From: Thorsten Ottosen [mailto:nesotto@cs.auc.dk] Sent: Monday, February 14, 2005 4:19 AM To: boost@lists.boost.org Subject: [boost] [iterators] request for utility iterator Hi all, I often want to iterate over just the values of a map or perhaps just the keys of a map. Therefore I would like to see the following iterator adapters in the iterator library: template< class Map > struct map_key_iterator; template< class Map > struct map_value_iterator; template< class Map > struct map_const_value_iterator; I have outlined an implementation in the attached file, but basically it just a wrapper around transform_iterator<typename Map::iterator>. Comments? br Thorsten