"has_virtual_destructor">has_virtual_destructor</a>
        </li>
</ul></div>
<p>
      The following traits classes can't be portably implemented in the C++ language,
      although in practice, the implementations do in fact do the right thing on
      all the compilers we know about:
    </p>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
          <a class="link" href="reference/is_empty.html" title="is_empty">is_empty</a>
        </li>
<li clas