title: Form validation, call function not working in codeigniter 3.0.3
body: <p>This is a small rule for checking select option, but it doesn't work</p>
  
  <pre><code>array(
      'field'=&gt;'student_class',
      'label'=&gt;'Student Class',
      array(
          'required',
          array(
              'student_class_callable',
              function($str)
              {
                  if($str == 0)
                  {
                      return FALSE;
                  }
                  return TRUE;
              },
          ),
      ),
      'errors' =&gt; array(
           'required' =&gt; 'Please Select Student Class',
      ),
  ),
  </code></pre>
  
  <p>other field are being verified by the form validation, but not one</p>
  
  <p>select option look like this</p>
  
  <pre><code>&lt;select name="student_class"&gt;
      &lt;option value="0"&gt;Please Select Class&lt;/option&gt;
      &lt;option value="1"&gt;First&lt;/option&gt;
      &lt;option value="2"&gt;Second&lt;/option&gt;
  &lt;/select&gt;
  </code></pre>