s="identifier">function</span><span class="special">&lt;</span> <span class="identifier">R</span> <span class="special">&gt;</span><span class="special">::</span><span class="identifier">impl</span> <span class="special">{</span>
<span class="keyword">public</span><span class="special">:</span>
  <span class="comment">// <a class="link" href="impl_template.html#boost.log.attributes.function.impl_templateconstruct-copy-destruct">construct/copy/destruct</a></span>
  <span class="keyword">explicit</span> <a cl