I've been playing around with Ruby's mixins today and It's really fun. Here's a snippet:

module Greeter
  
  def who_am_i?
    "#{self.class.name}"
  end

  def greet
    puts "Hello #{@name}"
  end
  
end

class Student
  
  def initialize(n)
    @name = n
  end
  
  include Greeter
end

class Teacher
  
  def initialize(n)
    @name = n
  end
  
  include Greeter
end

Now fire up irb and do this: