 vertex_index = 0;

  template <class T = int>
  struct dfs_visitor
  {};
}

BOOST_PARAMETER_NAME(graph)

BOOST_PARAMETER_NAME(visitor)
BOOST_PARAMETER_NAME(root_vertex)
BOOST_PARAMETER_NAME(index_map)
BOOST_PARAMETER_NAME(color_map)

BOOST_PARAMETER_FUNCTION((void), f, tag,
  (required (graph, *))
''') -->
<!-- @example.append(') {}') -->
<!-- @test('compile') -->
<p>If <tt class="docutils literal">color_map</tt> were strictly going to be modified but not examined,
we could have written <tt class="docutils