Implementation for Java-like Interfaces in Ruby

interfaces.rb

#!/usr/bin/env ruby
#encoding: utf-8

############ Interface code
class InterfaceClass < Module
  private
  def included(klass)
    if klass != Object
      @_implemented.each do |m|
        if !klass.method_defined?(m)
          raise NoMethodError.new("method '#{m}' from Interface '#{self}' not implemented for #{klass}")
        end
      end
    end
  end

  def initialize(*methods, &interface)
    @_implemented = methods.flatten
    interface.call if !interface.nil?
  end

  public
  def child(*methods, &interface)
    self.class.new(@_implemented + methods) do
      interface.call if !interface.nil?
    end
  end
end

Interface = InterfaceClass.new
############ End interface code

############ Test code
OneInterface = Interface.child(:one_method, :method_too) do
  GRAVITY = 9.81
end

ExampleInterface = OneInterface.child(:third_method)

class SomeClass
  def one_method
    puts GRAVITY
  end

  def method_too
    puts "2"
  end

  include ExampleInterface # --> method 'third_method' from Interface 'ExampleInterface' not implemented for SomeClass
end
############ End test code