title: How to set a variable in JSF?
body: <p>My code here iterates the columns for each row and the <code>rendered</code> attribute is calculated every iteration, overcalling <code>testRule</code>.</p>
  
  <pre><code>&lt;p:dataTable ...&gt;
      &lt;p:column ...&gt;
          ...
      &lt;/p:column&gt;
  
      &lt;p:column rendered="#{managedBean.testRule('rules.canDoActions')}"&gt;
          &lt;!-- Action buttons --&gt;
          &lt;h:commandButton ...&gt;
          &lt;h:commandButton ...&gt;
      &lt;/p:column&gt;
  &lt;/p:dataTable&gt;
  </code></pre>
  
  <p>To get better performance, I was wondering to set the result into a variable, but I don't know how... It would become something like this:</p>
  
  <pre><code>   &lt;?:??? var="canDoActions" value="#{managedBean.testRule('rules.canDoActions')}"&gt;
     &lt;p:dataTable ...&gt;
          &lt;p:column ...&gt;
              ...
          &lt;/p:column&gt;
  
          &lt;p:column rendered="#{canDoActions}"&gt;
              &lt;!-- Action buttons --&gt;
              &lt;h:commandButton ...&gt;
              &lt;h:commandButton ...&gt;
          &lt;/p:column&gt;
      &lt;/p:dataTable&gt;
  </code></pre>
  
  <p>Also, I'm not allowed to use <em>Core Tag Library</em>, wich means that <code>&lt;c:set ../&gt;</code> is out of question.</p>
  
  <p>In that scope, how could I set a variable? Or, if not possible, what do you suggest to solve the performance?</p>