Visibility of Methods in Models

Cạn lời...

You can't call $this->Xpto_model->protectedMethodFromMyModel(); because protectedMethodFromMyModel() method protected,
Method cant call is extends class.

Link: http://php.net/manual/en/language.oop5.visibility.php
http://stackoverflow.com/questions/43615...-protected

Thanks for your help.
But the point is: Why is running without errors when i call protected method from MY_model?
public function doSomething(){
        $this->load->model("Product_model", "product_m");
        $this->product_m->publicMethodMyModel();
        $this->product_m->protectedMethodMyModel(); // here is the problem. This call should generate an error but it is not.
        $this->product_m->publicMethodProduct();
//     $this->product_m->protectedMethodProduct();
}