with_holes </font>concept,
specialize the geometry concept meta-function for that type.&nbsp; In
the example below CPolygon45WithHoles is registered as a model of
polygon<font face="Times New Roman">_45_with_holes&nbsp;</font> concept.</p>
      <p> <font face="Courier New">template &lt;&gt;<br />
struct geometry_concept&lt;CPolygon45WithHoles&gt; { typedef
polygon_45_with_holes_concept type; };</font></p>
      <p> <font face="Times New Roman">The semantic of a
polygon_45_with_holes is a polygon_45 that it