public function isValid($value)
    {
        $this->setValue($value);

        $pattern = '/^[a-z0-9_\-]*[a-z0-9]$/i';

        $this->pageNameOk = true;

        if (!preg_match($pattern, $value)) {
            $this->error(self::PAGE_NAME);
            $this->pageNameOk = false;
        }

        return $this->pageNameOk;
    }