 can build an <span class="concept">ArgumentPack</span> <em>object</em> by invoking
its function call operator:</p>
<pre class="literal-block">
parameter::parameters&lt;
    required&lt;tag::name, is_convertible&lt;_,char const*&gt; &gt;
  , optional&lt;tag::index, is_convertible&lt;_,int&gt; &gt;
&gt; spec;

char const sam[] = &quot;sam&quot;;
int twelve = 12;

int z0 = print_name_and_index( <strong>spec(</strong>sam, twelve<strong>)</strong> );

int z1 = print_name_and_index(
   <strong>spec(</strong>_ind