function toString()
    {
        $modes = array();
        $levels = array(E_USER_NOTICE  => 'notice',
                        E_USER_WARNING => 'warning',
                        E_USER_ERROR   => 'error');
        if ($this->mode & PEAR_ERROR_CALLBACK) {
            if (is_array($this->callback)) {
                $callback = (is_object($this->callback[0]) ?
                    strtolower(get_class($this->callback[0])) :
                    $this->callback[0]) . '::' .
                    $this->callback[1];
            } else {
                $callback = $this->callback;
            }
            return sprintf('[%s: message="%s" code=%d mode=callback '.
                           'callback=%s prefix="%s" info="%s"]',
                           strtolower(get_class($this)), $this->message, $this->code,
                           $callback, $this->error_message_prefix,
                           $this->userinfo);
        }
        if ($this->mode & PEAR_ERROR_PRINT) {
            $modes[] = 'print';
        }
        if ($this->mode & PEAR_ERROR_TRIGGER) {
            $modes[] = 'trigger';
        }
        if ($this->mode & PEAR_ERROR_DIE) {
            $modes[] = 'die';
        }
        if ($this->mode & PEAR_ERROR_RETURN) {
            $modes[] = 'return';
        }
        return sprintf('[%s: message="%s" code=%d mode=%s level=%s '.
                       'prefix="%s" info="%s"]',
                       strtolower(get_class($this)), $this->message, $this->code,
                       implode("|", $modes), $levels[$this->level],
                       $this->error_message_prefix,
                       $this->userinfo);
    }