er">pbase_type</span><span class="special">(</span> <span class="identifier">fd</span> <span class="special">),</span> <span class="identifier">base_type</span><span class="special">(</span> <span class="special">&amp;</span><span class="identifier">member</span> <span class="special">){}</span>
    <span class="comment">//...</span>
<span class="special">};</span>
</pre>
<p>
      The base-from-member idiom is an implementation detail, so it should not be
      visible to the clients (or any derived classe