d><code>arity</code></td><td>The metafunction's arity, i.e. the number of its template parameters, including the defaults. </td></tr>
<tr><td><code>fun</code></td><td>The metafunction's name. </td></tr>
<tr><td><code>params</code></td><td><a href="http://www.boost.org/libs/preprocessor/doc/index.html">PP</a>-tuple of the metafunction's parameter names, in their original order. </td></tr>
</table>
<p>
<h3>Example</h3>
<p>
<pre>
template&lt; typename T, typename U = int &gt; struct f
{
    typedef T type[size