mixins with classes

Testing.rb

module Testing
  
  def about_self?
    "(\##{self.object_id}): #{self.to_s}"
  end
  
end

class Foo 

  include Testing

  def initialize
    @word = 'foo'
  end
  
  def to_s
    "I am a simple Foo class. Nothing more, nothing less."
  end

end

class Bar 

  include Testing

  def initialize
    @word = 'bar'
  end
  
  def to_s
    "I am a simple Bar class. Combined with a Foo class, we create Foo Bar."
  end

end

foo = Foo.new
bar = Bar.new
foo.about_self?
bar.about_self?