title: Using C#'s ref features on (dictionary) indexers
body: <p>I was wondering whether it is possible to use C#'s <code>ref return</code> on (dictionary) indexers or properties which define a <code>set</code> and <code>get</code> accessor, e.g.:</p>
  
  <pre><code>readonly Dictionary&lt;string, int&gt; dictionary = ...;
  
  
  ref int v = ref dictionary["foo"];
  //          ^^^^^^^^^^^^^^^^^^^^^
  // CS0206: A property or indexer may not be passed as an out or ref parameter
  v = 42;
  </code></pre>
  
  <p>Is it possible to somehow provide <code>ref</code> functionality to properties or indexers (without using reflection)? If so, how?</p>
  
  <p><hr/>
  I know, that the error message is clear in that sense - however, I was wondering which would be the optimal way to implement its <em>semantics</em>.</p>