Hi,

just mentioning that I think the documentation for the Polygon concept needs updating with respect to this line:

there must be a specialization of traits::ring_type defining the type of its exterior ring and interior rings as type

which I presume should actually refer to ring_const_type and ring_mutable_type? At least, it doesn't work for me when I specialize traits::ring_type, as I get this kind of error:

error: specialization of ‘template<class Geometry> struct boost::geometry::ring_type’ in different namespace [-fpermissive]

Cheers.

Jeremy