title: Iterator for custom container with derived classes
body: <p>I've a custom container which is implemented in two different ways, but with a single interface. some thing like this.</p>
  
  <pre><code>    class Vector 
      {
         virtual Iterator begin() = 0;
         virtual Iterator end () = 0 ;
  
      ... // some more functions.
      } ;
  
      class VectorImplA : public Vector
      {
         Iterator begin() { return m_data.begin() ; }
         Iterator end () { return m_data.end() ; }
      private:
         SomeFloatContainer m_data ;
      } ;
  
      class VectorImplB : public Vector
      {
         Iterator begin() { return m_data.end() ; }
         Iterator end() ; { return m_data.end() ; }
  
  
      private:
          std::vector &lt;float&gt; m_data ;
  
      } ;
  </code></pre>
  
  <p>What I need is a unified interface to Iterator, so that I'can use it in base class. Any Ideas ?</p>