Based on the conversation with @ardetrick and according to the comment-guide of kernel Yii file the below could be confuse a lot of members
/**
* Validates the attribute of the object.
* --> If there is any error, the error message is added to the object.
* @param CModel $object the object being validated
* @param string $attribute the attribute being validated
*/
protected function validateAttribute($object,$attribute)
{
}