Delegation to array

delegation_to_array.rb

class Delegator
  def initialize(array)
    @array = array
  end

  def method_missing(method, *args, &block)
    @array.send(method, *args, &block)
  end
end

puts Delegator.new([1,2]) + Delegator.new([2,3])

__END__

On MRI 1.9.3 & 2.1.2:
1
2
2
3

On JRuby 1.7.15:
TypeError: can't convert Delegator into Array
               + at org/jruby/RubyArray.java:3062
  method_missing at delegate_array.rb:7
          (root) at delegate_array.rb:11