</p>
<pre class="literal-block">
namespace people
{
  namespace tag { struct name; struct age;  }

  namespace // unnamed
  {
    boost::parameter::keyword&lt;tag::name&gt;&amp; <strong>name</strong>
    = boost::parameter::keyword&lt;tag::name&gt;::instance;
    boost::parameter::keyword&lt;tag::age&gt;&amp; <strong>age</strong>
    = boost::parameter::keyword&lt;tag::age&gt;::instance;
  }

  BOOST_PARAMETER_FUNCTION(
      (void), g, tag, (optional (name, *, &quot;bob&quot;)(age, *, 42)))
  {
      std::