Dear Luke (& others), Here's some test code, followed by the errors that I get when I try to compile it. It boils down to some confusion about whether set is a type or a function. Am I doing something that isn't allowed? Thanks for any suggestions. #include <boost/polygon/polygon.hpp> template<typename COORD_T> struct Box { typedef COORD_T coord_t; coord_t x0; coord_t y0; coord_t x1; coord_t y1; }; typedef int screen_coord_t; typedef Box<screen_coord_t> screen_box_t; namespace boost { namespace polygon { template <> struct geometry_concept<screen_box_t> { typedef rectangle_concept type; }; template <> struct rectangle_traits<screen_box_t> { typedef screen_coord_t coordinate_type; typedef std::pair<screen_coord_t,screen_coord_t> interval_type; static inline interval_type get(const screen_box_t& rectangle, orientation_2d orient) { return (orient==HORIZONTAL) ? std::make_pair(rectangle.x0,rectangle.x1) : std::make_pair(rectangle.y0,rectangle.y1); } }; }; }; typedef boost::polygon::polygon_90_set_data<screen_coord_t> markers_t; markers_t markers; void draw_marker(screen_box_t sb) { using namespace boost::polygon::operators; markers |= sb; } /usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2/bits/stl_set.h: In function ‘typename boost::enable_if<typename boost::polygon::gtl_and_3<boost::polygon::y_r_assign, typename boost::polygon::is_mutable_rectangle_concept<typename boost::polygon::geometry_concept<T>::type>::type, typename boost::polygon::is_rectangle_concept<typename boost::polygon::geometry_concept<T2>::type>::type>::type, rectangle_type_1>::type& boost::polygon::assign(rectangle_type_1&, const rectangle_type_2&) [with rectangle_type_1 = boost::polygon::rectangle_data<int>, rectangle_type_2 = Box<int>]’: /usr/local/src/gtl/boost/polygon/detail/iterator_geometry_to_set.hpp:34: instantiated from ‘boost::polygon::iterator_geometry_to_set<boost::polygon::rectangle_concept, rectangle_type>::iterator_geometry_to_set(const rectangle_type&, boost::polygon::direction_1d, boost::polygon::orientation_2d, bool) [with rectangle_type = Box<int>]’ /usr/local/src/gtl/boost/polygon/polygon_90_set_data.hpp:137: instantiated from ‘void boost::polygon::polygon_90_set_data<T>::insert(const geometry_type&, bool, boost::polygon::orientation_2d) [with geometry_type = Box<int>, T = int]’ /usr/local/src/gtl/boost/polygon/polygon_90_set_data.hpp:113: instantiated from ‘void boost::polygon::polygon_90_set_data<T>::insert(iT, iT, boost::polygon::orientation_2d) [with iT = const Box<int>*, T = int]’ /usr/local/src/gtl/boost/polygon/detail/polygon_90_set_view.hpp:318: instantiated from ‘typename boost::enable_if<typename boost::polygon::gtl_and<boost::polygon::operators::y_ps90_pe, typename boost::polygon::is_polygon_90_set_type<polygon_set_type_2>::type>::type, boost::polygon::polygon_90_set_data<coordinate_type> >::type& boost::polygon::operators::operator+=(boost::polygon::polygon_90_set_data<coordinate_type>&, const geometry_type_2&) [with coordinate_type_1 = int, geometry_type_2 = Box<int>]’ /usr/local/src/gtl/boost/polygon/detail/polygon_90_set_view.hpp:329: instantiated from ‘typename boost::enable_if<typename boost::polygon::gtl_and<boost::polygon::operators::y_ps90_be, typename boost::polygon::is_polygon_90_set_type<polygon_set_type_2>::type>::type, boost::polygon::polygon_90_set_data<coordinate_type> >::type& boost::polygon::operators::operator|=(boost::polygon::polygon_90_set_data<coordinate_type>&, const geometry_type_2&) [with coordinate_type_1 = int, geometry_type_2 = screen_box_t]’ testpoly.cc:41: instantiated from here /usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2/bits/stl_set.h:71: error: ‘template<class _Key, class _Compare, class _Alloc> class std::set’ is not a function, /usr/local/src/gtl/boost/polygon/point_concept.hpp:77: error: conflict with ‘template<class T, class coordinate_type> void boost::polygon::set(T&, boost::polygon::orientation_2d, coordinate_type, typename boost::enable_if<typename boost::polygon::is_mutable_point_concept<typename boost::polygon::geometry_concept<T>::type>::type, void>::type*)’ /usr/local/src/gtl/boost/polygon/rectangle_concept.hpp:192: error: in call to ‘set’ /usr/local/src/gtl/boost/polygon/detail/iterator_geometry_to_set.hpp:34: instantiated from ‘boost::polygon::iterator_geometry_to_set<boost::polygon::rectangle_concept, rectangle_type>::iterator_geometry_to_set(const rectangle_type&, boost::polygon::direction_1d, boost::polygon::orientation_2d, bool) [with rectangle_type = Box<int>]’ /usr/local/src/gtl/boost/polygon/polygon_90_set_data.hpp:137: instantiated from ‘void boost::polygon::polygon_90_set_data<T>::insert(const geometry_type&, bool, boost::polygon::orientation_2d) [with geometry_type = Box<int>, T = int]’ /usr/local/src/gtl/boost/polygon/polygon_90_set_data.hpp:113: instantiated from ‘void boost::polygon::polygon_90_set_data<T>::insert(iT, iT, boost::polygon::orientation_2d) [with iT = const Box<int>*, T = int]’ /usr/local/src/gtl/boost/polygon/detail/polygon_90_set_view.hpp:318: instantiated from ‘typename boost::enable_if<typename boost::polygon::gtl_and<boost::polygon::operators::y_ps90_pe, typename boost::polygon::is_polygon_90_set_type<polygon_set_type_2>::type>::type, boost::polygon::polygon_90_set_data<coordinate_type> >::type& boost::polygon::operators::operator+=(boost::polygon::polygon_90_set_data<coordinate_type>&, const geometry_type_2&) [with coordinate_type_1 = int, geometry_type_2 = Box<int>]’ /usr/local/src/gtl/boost/polygon/detail/polygon_90_set_view.hpp:329: instantiated from ‘typename boost::enable_if<typename boost::polygon::gtl_and<boost::polygon::operators::y_ps90_be, typename boost::polygon::is_polygon_90_set_type<polygon_set_type_2>::type>::type, boost::polygon::polygon_90_set_data<coordinate_type> >::type& boost::polygon::operators::operator|=(boost::polygon::polygon_90_set_data<coordinate_type>&, const geometry_type_2&) [with coordinate_type_1 = int, geometry_type_2 = screen_box_t]’ testpoly.cc:41: instantiated from here /usr/local/src/gtl/boost/polygon/rectangle_concept.hpp:192: error: no matching function for call to ‘set(boost::polygon::rectangle_data<int>&, boost::polygon::orientation_2d_enum, std::pair<int, int>)’ /usr/local/src/gtl/boost/polygon/detail/iterator_geometry_to_set.hpp:34: instantiated from ‘boost::polygon::iterator_geometry_to_set<boost::polygon::rectangle_concept, rectangle_type>::iterator_geometry_to_set(const rectangle_type&, boost::polygon::direction_1d, boost::polygon::orientation_2d, bool) [with rectangle_type = Box<int>]’ /usr/local/src/gtl/boost/polygon/polygon_90_set_data.hpp:137: instantiated from ‘void boost::polygon::polygon_90_set_data<T>::insert(const geometry_type&, bool, boost::polygon::orientation_2d) [with geometry_type = Box<int>, T = int]’ /usr/local/src/gtl/boost/polygon/polygon_90_set_data.hpp:113: instantiated from ‘void boost::polygon::polygon_90_set_data<T>::insert(iT, iT, boost::polygon::orientation_2d) [with iT = const Box<int>*, T = int]’ /usr/local/src/gtl/boost/polygon/detail/polygon_90_set_view.hpp:318: instantiated from ‘typename boost::enable_if<typename boost::polygon::gtl_and<boost::polygon::operators::y_ps90_pe, typename boost::polygon::is_polygon_90_set_type<polygon_set_type_2>::type>::type, boost::polygon::polygon_90_set_data<coordinate_type> >::type& boost::polygon::operators::operator+=(boost::polygon::polygon_90_set_data<coordinate_type>&, const geometry_type_2&) [with coordinate_type_1 = int, geometry_type_2 = Box<int>]’ /usr/local/src/gtl/boost/polygon/detail/polygon_90_set_view.hpp:329: instantiated from ‘typename boost::enable_if<typename boost::polygon::gtl_and<boost::polygon::operators::y_ps90_be, typename boost::polygon::is_polygon_90_set_type<polygon_set_type_2>::type>::type, boost::polygon::polygon_90_set_data<coordinate_type> >::type& boost::polygon::operators::operator|=(boost::polygon::polygon_90_set_data<coordinate_type>&, const geometry_type_2&) [with coordinate_type_1 = int, geometry_type_2 = screen_box_t]’ testpoly.cc:41: instantiated from here /usr/lib/gcc/i486-linux-gnu/4.1.2/../../../../include/c++/4.1.2/bits/stl_set.h:71: error: ‘template<class _Key, class _Compare, class _Alloc> class std::set’ is not a function, /usr/local/src/gtl/boost/polygon/point_concept.hpp:77: error: conflict with ‘template<class T, class coordinate_type> void boost::polygon::set(T&, boost::polygon::orientation_2d, coordinate_type, typename boost::enable_if<typename boost::polygon::is_mutable_point_concept<typename boost::polygon::geometry_concept<T>::type>::type, void>::type*)’ /usr/local/src/gtl/boost/polygon/rectangle_concept.hpp:193: error: in call to ‘set’ /usr/local/src/gtl/boost/polygon/rectangle_concept.hpp:193: error: no matching function for call to ‘set(boost::polygon::rectangle_data<int>&, boost::polygon::orientation_2d_enum, std::pair<int, int>)’