Progress bar

  class Spinner
    private

      @work
      @job

      def spinner
        return(['\\','|','/','-'][@i%4])
      end

    public

      def initialize max_iterations, job="Working"
        $stdout.sync = true
        @max_iterations = max_iterations
        @job = job
        @i=0
        @delta_count = 0
        @start_time = Time.now
      end

      def update
        @i += 1
        @delta_count += 1
        fraction = (@i.to_f/@max_iterations)
        if @i%10 == 0
          now = Time.now
          delta_time = now-@start_time
          time_per_iteration = delta_time.to_f / @delta_count
          x = (@max_iterations-@i) * time_per_iteration
          eta_string = "#{(x.to_i/60).to_i} mins #{x.to_i%60} secs   "
          @delta_count=0
          @start_time = Time.now
        else
          eta_string = "\b"
        end
        printf("\r#{@job}: %s %3.2f%s ETA:  %s",spinner,(fraction)*100,"%",eta_string)
      end
  end