ewed as a model of any of
its refinements if it is determined at runtime to conform to the
restriction of those concepts.&nbsp; This concept casting is
accomplished through the
      <font face="Courier New">view_as&lt;&gt;()</font> function.</p>
      <p><font face="Courier New">view_as&lt;rectangle_concept&gt;(polygon_45_with_holes_object)</font><br />
      <font face="Courier New">view_as&lt;polygon_90_concept&gt;(polygon_45_with_holes_object)</font><br />
      <font face="Courier New">view_as&lt;polyg