Using include

thing1.rb

module Logger
  def log str
    p str
  end  
end

class Thing1
  include Logger
  
  begin
    log "this doesn't work from class"
  rescue Exception => e
    p e                           # => #<NoMethodError: undefined method `log' for Thing1:Class>
  end
  
  def test_log
    log "this does work from instance"
  end
end


Thing1.new.test_log               # => "this does work from instance"
begin
  Thing1.log "this doesn't work from class again"
rescue Exception => e
  p e                             # => #<NoMethodError: undefined method `log' for Thing1:Class>
end