[Qgis-developer] new geom function: combine cascaded

[Carson Farmer]

Hi Martin,

> From a brief look I have two comments:
> - I would prefer the combineCascaded to be a static function - it
> makes more sense to pass all N geometries in the list, not N-1
> geometries in the list and 1 geometry that triggers the operation.
ok, good point... done.
> - I believe the cascaded union has been added in geos 3.1, so we
> should either make it conditional (and fall back to classical union
> for geos 3.0) or rise the minimal geos version to 3.1.
hmm, right, well what do we think is the best way to go here? If we
fall back on a regular union, it could be 100s of times slower in some
cases!
> - the typeId choice should be probably improved to check all input
> geometries - if they're not of the same type, geometry collection will
> be used
ok, also a good point... done (hopefully my implementation is
relatively intelligent?)

Carson

-- 
Carson J. Q. Farmer
ISSP Doctoral Fellow
National Centre for Geocomputation
National University of Ireland, Maynooth,
http://www.carsonfarmer.com/