class NameGenerator
  attr_accessor :length

  def initialize(length)
    @length = length
  end

  def generate
    available_symbols = ('a'..'z').to_a + (0..9).to_a
    name = String.new
    @length.times { name += available_symbols[rand(0..available_symbols.length)].to_s }
    name
  end
end

a = NameGenerator.new(25)
p a.generate