-----Original Message-----
From: geos-devel [mailto:geos-devel-boun...@lists.osgeo.org] On Behalf Of
Paul Ramsey
Sent: Thursday, October 15, 2020 12:39 PM
To: roger.biv...@nhh.no; GEOS Development List <geos-
de...@lists.osgeo.org>
Subject: Re: [geos-devel] Is Overlay-NG active?
The "plan" as I see it is to, for 3.9, actually make NG the default for the
standard intersection(), union(), unaryunion(), difference(), symdifference()
calls. So the "test" will be "is this GEOS 3.9". I don't want to go forward into
the future where a released GEOS has two potential behaviour modes, that
way lies madness. We needed to keep a switch in place to allow other
development to continue and to compare before/after easily on the working
branch (and to allow people like you to test the new without suddenly have
everything break on ordinary testing).
Does that make sense?
P
On Oct 15, 2020, at 8:59 AM, Roger Bivand <roger.biv...@nhh.no> wrote:
Can I ask whether there is, or could be, a function exposed in the C_API, or
a header variable say in geoc_c.h, showing whether the running GEOS is
using Overlay-NG or not?
After help from the list, I've now run checks on R packages either
themselves linking to GEOS, or using functions from packages which do link
to GEOS. A half-dozen or so fail on unit tests, typically because the ordering
of coordinates varies (say same polygon, but starting at a different place), or
the ordering of sub-geometries (say slivers from a Union operation) varies
from before Overlay-NG. The objects are the same (for given precision), but
unit tests in packages compare the WKT of the output geometry with the
expected WKT (often generated from output before Overlay-NG).
So if we could provide a way for the unit tests to compare correctly
branching on Overlay-NG or not, the package maintainers could avoid having
to scramble when platforms and R packages linking to GEOS begin to appear.
Another question raised by package maintainers - do we know when 3.9.0
may be expected, and will it have Overlay-NG? However, providing them
with an easy way to ask the GEOS runtime if it is Overlay-NG or not will
relieve the pressure.
Anyway, the failure count is very low, a half-dozen from hundreds is fine
(and if they didn't write tests, that isn't our problem...).
Roger
--
Roger Bivand
Department of Economics, Norwegian School of Economics, Helleveien 30,
N-5045 Bergen, Norway.
voice: +47 55 95 93 55; e-mail: roger.biv...@nhh.no
https://orcid.org/0000-0003-2392-6140
https://scholar.google.no/citations?user=AWeghB0AAAAJ&hl=en
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