Using extend and include

Thing3.rb

module Logger
  def log str
    p str
  end  
end

class Thing3
  include Logger
  extend Logger
  
  log "this does work from class"   # => "this does work from class"
  
  def test_log
    log "this does work from instance"
    Thing3.log "this does work from class (via class in instance)"
  end
end

Thing3.new.test_log                 # => "this does work from instance"
                                    # => "this does work from class (via class in instance)"