title: Force subclasses of an interface to implement ToString
body: <p>Say I have an interface <code>IFoo</code> and I want all subclasses of <code>IFoo</code> to override Object's <code>ToString</code> method. Is this possible? </p>
  
  <p>Simply adding the method signature to IFoo as such doesn't work:</p>
  
  <pre><code>interface IFoo
  {
      String ToString();
  }
  </code></pre>
  
  <p>since all the subclasses extend <code>Object</code> and provide an implementation that way, so the compiler doesn't complain about it. Any suggestions?</p>