Service object simplifications

method_object.rb

class MethodObject < Module
  def initialize(output_name)
    @output_name = output_name
  end

  module InstanceMethods
    attr_reader :input

    def initialize(input)
      @input = input
    end
  end

  def included(descendant)
    output_name = @output_name
    descendant.send(:include, InstanceMethods)
    descendant.define_singleton_method(:run) do |input|
      new(input).public_send(output_name)
    end
  end
end

class Processor
  include MethodObject.new(:result)

  def first
    split.first
  end

  def last
    split.last
  end

  def split
    input.split('.')
  end

  def result
    [last, first, last].join(".")
  end
end

p Processor.run("foo.bar") # => "bar.foo.bar"