progress_bar.rb

class ProgressBar
  # Prints progress like this:
  # Progress: (15%) [====          ]

  def initialize(total)
    @total = total
    @counter = 0
    @bar_width = 50
  end

  def inc
    @counter += 1
    print_progress_bar
  end

  def end
    @counter = @total
    print_progress_bar
  end

  private

  def print_progress_bar
    printf(
      "\rProgress: (%-.2f%%) [%-#{@bar_width}s]",
      percent_complete,
      "=" * bar_increments_complete
    )
  end

  def bar_increments_complete
    fraction_complete * @bar_width
  end

  def percent_complete
    fraction_complete * 100
  end

  def fraction_complete
    @counter.to_f / @total.to_f
  end
end