Geometry Boost List: [geometry] Why closure?

Subject: [geometry] Why closure?
From: TONGARI (tongari95_at_[hidden])
Date: 2013-06-20 05:26:30

Hi,

I'm not quite understand why we need traits::closure for Ring & Polygon,
aren't these always closed?
What should I expect if the closure is open? Should I see Ring as
Linestring then?

Thanks