user-specific operations different from <code class="computeroutput">T's</code> copy constructor. The default implementation of this trait is equivalent to:</p>
<pre class="programlisting"><span class="keyword">template</span><span class="special">&lt;</span><span class="keyword">typename</span> <span class="identifier">T</span><span class="special">&gt;</span>
<span class="keyword">class</span> <span class="identifier">old_value_copy</span> <span class="special">{</span>
<span class="keyword">public</span>