Single Instance of a class (ex.Logger)

logger.rb

class Logger
  def initialize
    @log = File.open("logfile.txt", "a")
  end
   
  @@instance = Logger.new
 
  def self.instance
    return @@instance
  end
 
  def log(msg)
    @log.puts(msg)
  end
 
  private_class_method :new
end
 
Logger.instance.log('log message 1')