code: public Object evaluate(String pAttributeName,
                             String pAttributeValue,
                             Class pExpectedType,
                             Tag pTag,
                             PageContext pPageContext,
                             Map functions,
                             String defaultPrefix)
              throws JspException {
          try {
              return sEvaluator.evaluate
                      (pAttributeValue,
                              pPageContext,
                              pExpectedType,
                              functions,
                              defaultPrefix);
          }
          catch (ELException exc) {
              throw new JspException
                      (MessageFormat.format
                              (Constants.ATTRIBUTE_EVALUATION_EXCEPTION,
                                              "" + pAttributeName,
                                              "" + pAttributeValue,
                                              exc.getMessage(),
                                      exc.getRootCause()), exc.getRootCause());
          }
      }
docs: Evaluates the expression at request time