从PHP中的父类调用方法？

I can't seem to figure out a way to call a method called insertValue();

My bootstrap takes the url and splits it into pieces so www.URL.com/register/register becomes

url[0]=register;  
url[1] = register;  
$controller = new url[0];  
$controller->loadModel();  
if islet($url[1])  
    $controller->{url[1]};  

class Controller { 
    public $model; 
    function __construct() { 
        $this->view = new View(); //(irrelevant) 
    } 
    public function loadModel($name) { 
        ... 
        $this->model = new $modelName; 
    }
}

The model class is as follows

class Model { 
    public $database;
    function__construct() { 
        $this->database = new Database();
    } 
} 

So the database class is as follows

class Database { 
    insertValue(){ 
    ... 
    }
}

Now, I have a bootstrap which creates a register class that extends controller as follows:

class Register extends Controller {
    function__construct(){
        parent::__construct();
    }
    public static function register (){
        HERE IS WHERE I WANT TO CALL THE INSERT VALUE FUNCTION FROM DATABASE CLASS
    }
}

The bootstrap also creates my model class by saying Register->loadModel(); which simply looks like this:

class registerModel extends Model {

    function __construct() {
        parent::__construct();
   }

I can't at all figure out how to call the insertValue function. I tried $this->model->database->insertValue(); but that didn't work.

P.S. I notice that when I call this function, that the code beneath it does not get called, but no error message is given.

have you tried $this->model->database->insertValue() ? after calling loadModel() inside your controller construct.