ame="spirit.advanced.customize.clear_value.when_to_implement"></a></span><a class="link" href="clear_value.html#spirit.advanced.customize.clear_value.when_to_implement">When
          to Implement</a>
        </h6>
<p>
          The customization point <code class="computeroutput"><span class="identifier">clear_value</span></code>
          needs to be implemented for a specific type whenever this type is to be
          used as an attribute to be stored into a STL container and if the type
          cannot