I understand what the original poster was trying to convey, and your opinion is valid, but they both need much more clarification than saying things should be interchangeable.
Indeed, things have to be clear on that point, and I'm a bit confused about what really constitutes the concept of a point. What I have understood until now is that a class is the point if it exposes: * the value<>() getter and setter * coordinate_type * coordinate_count and that besides this, the .x and .y of the point_xy class were just some syntactic helpers provided for an easier external use of this class. But I see that almost all the algorithms use .x and .y, which means that they won't work with the basic concept I just described. Shouldn't all those algorithms be implemented in terms of value<>() accesses ? Some headers that use .x and .y: area.hpp strategies_point_xy.hpp centroid.hpp correct.hpp envelope.hpp intersection_linestring.hpp intersection_segment.hpp Bruno