class Spinner
  def initialize printer=nil
    @spinner = %w[| / - \\]
    @count   = 0
    @printer ||= $stderr
  end

  def print
    @printer.print "\r"+@spinner[@count]
    @count += 1
    @count = 0 if @count > @spinner.size - 1
  end

  def self.print
    @spinner ||= new
    @spinner.print
  end
end

# 50.times{ Spinner.print; sleep 0.1 }