title: How to set a boost::optional back to an uninitialized state?
body: <p>How can I "reset"/"unset" a <code>boost::optional</code>?</p>
  
  
  
  <pre class="lang-cpp prettyprint-override"><code>optional&lt;int&gt; x;
  
  if( x )
  {
    // We won't hit this since x is uninitialized
  }
  x = 3;
  if( x )
  {
    // Now we will hit this since x has been initialized
  }
  // What should I do here to bring x back to uninitialized state?
  if( x )
  {
    // I don't want to hit this
  }
  </code></pre>