title: What does T&& (double ampersand) mean in C++11?
body: <p>I've been looking into some of the new features of C++11 and one I've noticed is the double ampersand in declaring variables, like <code>T&amp;&amp; var</code>.</p>
  
  <p>For a start, what is this beast called? I wish Google would allow us to search for punctuation like this.</p>
  
  <p>What exactly does it <em>mean?</em></p>
  
  <p>At first glance, it appears to be a double reference (like the C-style double pointers <code>T** var</code>), but I'm having a hard time thinking of a use case for that.</p>