simple timer with dynamic average

timer.rb

class Timer

  attr_reader :diff, :sum, :step

  def initialize
    reset!
  end

  def mark!
    new_mark = now
    
    if @mark
      @sum += @diff
      @diff = new_mark - @mark
      @step += 1
    end
    
    @mark = new_mark
  end
  
  def avg
    unless @step.zero?
      (@sum + @diff) / @step
    else
      0.0
    end
  end
  
  def reset!
    @mark = nil
    @step = 0
    @diff = 0.0
    @sum = 0.0
  end
  
  private
  def now
    Time.now.to_f
  end
  
  
end