Acts as geolocatable

geolocatable.rb

module Geolocatable
  
    def acts_as_geolocatable(options = {})
      
      options = {:lat => 'lat', :lng => 'lng'}.merge(options)
      
      write_inheritable_attribute :acts_as_geolocatable_options, options
      class_inheritable_reader :acts_as_geolocatable_options, options
      
      include Geolocatable::Model
    end
    
    module Model
      extend ActiveSupport::Concern

      included do
        # Use like: :origin => [12.453,34.566], :within => 10
        scope :near, lambda{ |*args|
          origin = *args.first[:origin]
          if (origin).is_a?(Array)
            origin_lat, origin_lng = origin
          else
            origin_lat, origin_lng = origin.lat, origin.lng
          end
          origin_lat, origin_lng = Math::PI*origin_lat/180, Math::PI*origin_lng/180
          within = *args.first[:within]
          {
            :conditions => %(
              (ACOS(COS(#{origin_lat})*COS(#{origin_lng})*COS(RADIANS(#{lng_sql}))*COS(RADIANS(#{lng_sql}))+
              COS(#{origin_lat})*SIN(#{origin_lng})*COS(RADIANS(#{lat_sql}))*SIN(RADIANS(#{lng_sql}))+
              SIN(#{origin_lat})*SIN(RADIANS(#{lat_sql})))*3963) <= #{within[0]}
            ),
            :select => %( #{table_name}.* )
          }
        }

        # Bounds must be in the format: lat_lo, lng_lo, lat_hi, lng_hi
        scope :in_bounds, lambda{ |*args|
          bounds = *args.first[:bounds]
          lat_lo = bounds[0];
          lng_lo = bounds[1];
          lat_hi = bounds[2];
          lng_hi = bounds[3];
          {
            :conditions => %(
              (#{lat_sql} BETWEEN #{lat_lo} AND #{lat_hi}) AND
              (#{lng_sql} BETWEEN #{lng_lo} AND #{lng_hi})
            ),
            :select => %( #{table_name}.* )
          }
         }
      
      end
      
      module ClassMethods
        
        def lat_sql
          "#{table_name}.#{acts_as_geolocatable_options[:lat]}"
        end
  
        def lng_sql
          "#{table_name}.#{acts_as_geolocatable_options[:lng]}"
        end
        
    end
  end
end

This was my take on geolocation when the gems all had too much cruft or didnt work with Rails 3 or ruby 1.9.2