[geos-devel] GEOS Ruby bindings gem and extensions

Simon Tokumine si at tinypla.net
Tue Nov 30 17:22:43 EST 2010

This is fantastic news! Really looking forwards to the release, and it
lets me cross off a big to-do from my list :)

All the best,


On Tue, Nov 30, 2010 at 10:05 PM, J Smith <jay at zoocasa.com> wrote:
> Hello list!
> I work on a project that has been using the GEOS Ruby bindings for
> years and and we've been adding a bunch of extensions and
> modifications to it throughout that time. We've gotten to the point
> now where we'd like to release this code into the wild world of free
> software and open source and thought we'd drop a line to the
> geos-devel list to get some feedback and whatnot before releasing the
> code.
> We're specifically looking to release the following:
> - we've gemified the Ruby bindings portion of the GEOS library so it
> can be installed separately from the library itself. It still depends
> on the library, obviously, but can be built as a standalone gem. We've
> extracted the geos.i.in and ruby.i files from the GEOS tarball and
> wrote a gemspec and extconf.rb for it that extracts the relevant
> version information from geos_c.h and builds the SWIG output
> accordingly.
> - we've also extracted the Ruby test files and the gem has been tested
> on OSX and CentOS 5.5, although some of the tests appear to fail. (The
> tests themselves may be a bit stale, perhaps -- one test looks for a
> version string matching "3.0.0rc4-CAPI-1.3.3", for instance.)
> As for the extensions to the library, we've implemented the following
> in Ruby userland as wrappers and whatnot around the GEOS library:
> - a host of helper methods to make reading and writing to and from WKT
> and WKB easier. For instance, rather than
> Geos::WktReader.new.read('POINT(0 0')
> you can quickly use
> Geos.read('POINT(0 0)')
> The Geos.read method also works with WKB in both binary and hex,
> recognizes EWKB and EWKT and can read several of Google Maps
> JavaScript output formats that we use for our applications. There are
> also similar methods for outputting to WKT and WKB such as
> Geos::Geometry#to_wkt, #to_kml, #to_georss and a number of methods to
> output to Google Maps API v2-style JavaScript.
> - a bunch of helper methods to quickly grab some information from
> geometries like Geos::Point#lat and Geos::Point#lng.
> - in all, some 70+ helper methods have been added to Geos::Geometry types.
> - Geos::GeometryCollection has been made an Enumerable.
> We've also included some Rails integration for PostGIS, including:
> - automatic detection of geometry columns and just-in-time conversions
> for input and output to and from WKB when using PostGIS. This allows
> you to do stuff like this with your ActiveRecord models:
> m = MyModel.find(12345)
> m.the_geom # => spits out the untouched geometry value as a string in WKB
> m.the_geom_geos # => spits out the geometry wrapped in a Geos::Geometry object
> m.the_geom = 'POINT(0 0)' # => setters will automatically make
> conversions from any of the formats that the Geos.read can recognize,
> so Google Maps formats, WKT, WKB, etc. are all converted
> automatically.
> m.the_geom_wkt # => automatically converts to a WKT string
> m.the_geom_wkb_bin # => automatically converts to WKB in binary
> There's also some funky SRID handling code that will automatically
> look in the geometry_columns table to make conversions for you when
> necessary. Saving WKT as "SRID=default; POINT(0 0)" for instance will
> automatically set the SRID when saving the ActiveRecord, or the SRID
> can be specified manually.
> - multiple geometry columns are supported and detected for
> automatically. These column accessors are all generated dynamically at
> run time.
> - automatic generation of named scopes for ActiveRecord models. The
> usual suspects are supported:
> * st_contains
> * st_containsproperly
> * st_covers
> * st_coveredby
> * st_crosses
> * st_disjoint
> * st_equals
> * st_intersects
> * st_orderingequals
> * st_overlaps
> * st_touches
> * st_within
> * st_dwithin
> These let you chain together scopes to build geospatial queries:
> neighbourhood = Neighbourhood.find(12345)
> my_model = MyModel.active.
>  recent.
>  st_within(neighbourhood.the_geom_geos.envelope).
>  st_dwithin(point, 0.1).
>  all(
>   :limit => 10
>  )
> - we wrote this code for Rails 2.3 and are currently testing on Rails
> 3, but it appears that everything is working as expected and is
> working with Arel (hopefully!).
> Our plan at the moment would be to put the code up on to github along
> with the appropriate Rubygems releases. We'd like to license the
> extensions code under the MIT license as per the usual Ruby and Rails
> library terms. As for the gemified build of the GEOS bindings library
> itself, would the correct license in this case be the LGPL? We've
> included several files from the main GEOS library along with the Ruby
> test files, so would this extend that license to the rest of the gem,
> which includes only build files like a Rakefile, extconf.rb and a
> gemspec and such. We could otherwise license this gem as perhaps a
> combination license -- the files from the GEOS library would be marked
> as being covered under the LGPL, while the collection as a whole would
> be released under our preferred MIT license.
> We hope to release this code soon and hope it proves useful to the
> GEOS project and Ruby GIS coders. The GEOS Ruby library has been a
> real boon to our development, and we hope that our extensions and the
> gem build will be useful to others.
> Any comments and suggestions are appreciated.
> Cheers!
> J
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