On Tue, Feb 24, 2009 at 5:29 AM, Barend Gehrels <barend@geodan.nl> wrote:
What should the generic "area" algorithm return for point and linestring?... What should the generic "length" algorithm return for polygon?... What should the generic "centroid" algorithm return for point and linestring?... and for an invalid polygon (e.g. no points at all, or not closed)?...
Thanks, Barend
Are these generic "algorithms" or part of the concepts themselves? I think a number of options make sense for any particular library but not for the concepts -- I think area(p) should not be part of the point concept, and should not be available for a point archetype, but it may exist anyways in your particular library. Concepts don't usually "disallow" functions do they? (or do they?) As far as invalid polygons --- I am curious how one would go about creating a polygon that is not closed. I would tend to think that since you have a linestring, then a polygon must mean that the shape is closed. --John