title: a problem about singleton in ruby
body: <p>i am a newbie about ruby.
  should not the singleton class`s initialize function have any arguments?
  here is my code:</p>
  
  <pre><code>require 'singleton'
  class AAA
      attr :string , true
      include Singleton 
      def initialize(stirng)
          @string = "aaa";
      end
  end 
  a = AAA.instance("simpleton");
  puts a.string
  </code></pre>
  
  <p>i think should be correct.but the ruby also tell me :</p>
  
  <blockquote>
    <p>/usr/lib/ruby/1.8/singleton.rb:94:in `initialize': wrong number of arguments (0 for 1) (ArgumentError)</p>
  </blockquote>
  
  <pre><code>from /usr/lib/ruby/1.8/singleton.rb:94:in `new'
  from /usr/lib/ruby/1.8/singleton.rb:94:in `instance'
  </code></pre>
  
  <p>T___T</p>