>using </span>Widget_list = list&lt;Widget, Shm_classic_allocator&lt;Widget&gt;&gt;;</div>
<div class="line"><span class="keyword">using </span>Widget_list_vec = vector&lt;Widget_list, Shm_classic_allocator&lt;Widget_list&gt;&gt;;</div>
<div class="line"> </div>
<div class="line">Shm_classic_arena a(...); <span class="comment">// Let `a` be a SHM-classic arena storing *x among other things.</span></div>
<div class="line"> </div>
<div class="line">Widget_list_vec* x = <span class="comment">// ...obtain point