title: What is the purpose of using a reference to a reference in C++?
body: <p>In my adventures studying the boost libraries, I've come across function signatures that have parameters which are a reference to a reference to an object.</p>
  
  <p>Example:</p>
  
  <pre><code>void function(int &amp;&amp; i);
  </code></pre>
  
  <p>What is the purpose/benefit of doing it this way rather than simply taking a reference to an object? I assume there is one if it's in boost.</p>