span><span class="special">;</span>

<span class="keyword">struct</span> <span class="identifier">data</span>
<span class="special">{</span>
   <span class="keyword">int</span>               <span class="identifier">i_</span><span class="special">;</span>
   <span class="comment">//A vector holding still undefined class 'data'</span>
   <span class="identifier">vector</span><span class="special">&lt;</span><span class="identifier">data</span><span class="special">&gt;</span>      <span class="identifier">v_