ass="identifier">lock</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  <span class="keyword">long</span> <a class="link" href="weak_ptr.html#idp50619568-bb"><span class="identifier">use_count</span></a><span class="special">(</span><span class="special">)</span> <span class="keyword">const</span><span class="special">;</span>
  <span class="keyword">bool</span> <a class="link" href="weak_ptr.html#idp50622576-bb"><span c