how to use sparql client on rdf.rb

#step 1 - installation

sudo gem install sparql

#step 2 - test

# in test.rb
require 'sparql/client'

sparql = SPARQL::Client.new("http://dbpedia.org/sparql")

# SELECT * WHERE { ?s ?p ?o } OFFSET 100 LIMIT 10
query = sparql.select.where([:s, :p, :o]).offset(100).limit(10)

query.each_solution do |solution|
  puts solution.inspect
end

#step 3 - what we did? 

# creat SPARQL::Client instance
# ~> call initialize("http://dbpedia.org/sparql", {}, nil)
# @url =  RDF::URI.new("http://dbpedia.org/sparql")
# @headers = {'Accept' => "#{RESULT_JSON}, #{RESULT_XML}, text/plain"}
#
def initialize(url, options = {}, &block)
  @url, @options = RDF::URI.new(url.to_s), options
  @headers = {'Accept' => "#{RESULT_JSON}, #{RESULT_XML}, text/plain"}

  #no blocks given!
  if block_given?
    case block.arity
      when 1 then block.call(self)
      else instance_eval(&block)
    end
  end
end

#then called select, try to what happed
#
def select(*args)
  client = self
  result = Query.select(*args)
  (class << result; self; end).send(:define_method, :execute) do
    client.query(self)
  end
  result
end