title: Assigning outcome of another JSTL tag as value of one JSTL tag
body: <p>I've got this, which is working:</p>
  
  <pre><code>&lt;c:choose&gt;
      &lt;c:when test="${sometest}"&gt;
          Hello, world!
      &lt;/c:when&gt;
      &lt;c:otherwise&gt;
          &lt;fmt:message key="${page.title}" /&gt;
      &lt;/c:otherwise&gt;
  &lt;/c:choose&gt;
  </code></pre>
  
  <p>And I want to change it to this:</p>
  
  <pre><code>&lt;c:choose&gt;
      &lt;c:when test="${sometest}"&gt;
          &lt;c:set var="somevar" scope="page" value="Hello, world!"/&gt;
      &lt;/c:when&gt;
      &lt;c:otherwise&gt;
          &lt;c:set var="somevar" scope="page" value="&lt;fmt:message key="${page.title}"&gt;"
      &lt;/c:otherwise&gt;
  &lt;/c:choose
  </code></pre>
  
  <p>But of course the following line ain't correct:</p>
  
  <pre><code>&lt;c:set var="somevar" scope="page" value="&lt;fmt:message key="${page.title}"&gt;"
  </code></pre>
  
  <p>How can I assign to the <em>somevar</em> variable the string resulting from a  call to fmt:message?</p>