[postgis-users] Adding a new GEOS call to PostGIS

[Brian Hamlin]

It recently came up in the IRC channel FreeNode #postgis
that there is a GEOS TopologyPreserveSimplify, in addition
to Simplify2D.

I did a bit of checking just now.. on my machine, I see
nm /usr/local/pgsql/lib/liblwgeom.1.3.so

_LWGEOM_simplify2d
_pg_finfo_LWGEOM_simplify2d
_simplify2d_lwgeom

    and some others, but no TopologyPreserve anything

nm /usr/lcoal/lib/libgeos_c.1.4.1.dylib

_GEOSSimplify
_GEOSTopologyPreserveSimplify

and lastly, in lwpostgis.sql
   CREATE OR REPLACE FUNCTION simplify(geometry, float8)
     RETURNS geometry
     AS '$libdir/liblwgeom', 'LWGEOM_simplify2d'
     LANGUAGE 'C' IMMUTABLE STRICT;

--
since the last SQL line matches the exported symbol name from liblwgeom
exactly, minus the front _, looks like there is the exact entry point.

Clearly no parallel entry for TopologyPreseveSimplify

this makes me think that there is a little more to adding the call to
lwpostgis.sql than copying and pasting the declaration.

insights welcome
    -Brian