Print a random password tabula recta

recta.rb

# by John Cromartie
# idea from http://blog.jgc.org/2010/12/write-your-passwords-down.html
# via http://news.ycombinator.com/item?id=2016608

alpha = ("A".."Z").to_a
chars = alpha + 'abcdefghijklmnopqrstuvwxyz0123456789!@#$%^&*(){}[]-+=.,;:~'.chars.to_a

class Array
  def rand_el
    self[rand(size)]
  end
end

puts (["  "] + alpha).join(" ")
puts "  " + "--" * alpha.size

alpha.each do |row|
  puts row + "| " + (alpha.collect { |col| chars.rand_el }.join " ")
end