an example of a Class#to_s method from the minesweeper code found here: https://github.com/paradasia/minesweeper

gistfile1.rb

#@board and @size are defined in initialize

def to_s
  final_str = ""
  top_border = (0..(@size-1).to_a * " "
  final_str << "   | #{top_border}\n   | " + "--" * @size + "\n"
  @board.each_with_index do |line, y|
    final_str << " #{y} | #{line.map(&:to_s).join(" ")}\n"
  end
  #return a string! don't 'puts' it. : )
  final_str
end