title: Using Add with ForSingletonOf in StructureMap
body: <p>If have two classes <code>Class1</code> and <code>Class2</code> both implementing an interface <code>IInterface</code>.</p>
  
  <p>And now, if I need a singleton instance of each of these classes, would this be the right way to implement it?</p>
  
  <pre><code>c.ForSingletonOf&lt;IInterface&gt;().Use&lt;Class1&gt;().Named("Class1");
  c.ForSingletonOf&lt;IInterface&gt;().Add&lt;Class2&gt;().Named("Class2");
  </code></pre>
  
  <p>And then getting the instances like this:</p>
  
  <pre><code>container.GetInstance&lt;IInterface&gt;("Class1");
  container.GetInstance&lt;IInterface&gt;("Class2");
  </code></pre>
  
  <p>Is there anything wrong in this approach or is there a better approach?</p>