OOP: retrieve 'fathers' attributes from the 'child' object.

Question

Hi guys, here i am again ;)

My problem atm is with nested php classes, i have, for example, a class like this one:

class Father{
    public $father_id;
    public $name;
    public $job;
    public $sons;
    public function __construct($id, $name, $job){
        $this->father_id = $id;
        $this->name = $name;
        $this->job = $job;
        $this->sons = array();
    }

    public function AddSon($son_id, $son_name, $son_age){
        $sonHandler = new Son($son_id, $son_name, $son_age);
        $this->sons[] = $sonHandler;
        return $sonHandler;
    }

    public function ChangeJob($newJob){
        $this->job = $newJob;
    }
}

class Son{
    public $son_id;
    public $son_name;
    public $son_age;
    public function __construct($son_id, $son_name, $son_age){
        $this->son_id = $son_id;
        $this->son_name = $son_name;
        $this->son_age = $son_age;
    }
    public function GetFatherJob(){
        //how can i retrieve the $daddy->job value??
    }
}

that's it, a useless class to explain my problem. What im trying to do is:

$daddy = new Father('1', 'Foo', 'Bar');
//then, add as many sons as i need:
$first_son = $daddy->AddSon('2', 'John', '13');
$second_son = $daddy->AddSon('3', 'Rambo', '18');
//and i can get here with no trouble. but now, lets say i need
//to retrieve the daddy's job referencing any of his sons... how?
echo $first_son->GetFatherJob(); //?

So, every son must be indipendent from each other but inherits the attributes and values from the father one..

I've tryed with inheritance:

class Son extends Father{
[....]

But i'll have to declare the father attributes every time i add a new son..otherwise father's attributes will be null

Any help?

Answer 1

You can't unless you tell the sons who their father is. This could be done by adding a setFather() method to the son and calling in the addSon() method of the father.

eg.

class Son {
    protected $_father;
    // ...
    public function setFather($father) {
        $this->_father = $father;
    }

    public function getFather() {
        return $this->_father;
    }
}

class Father {
    // ...
    public function AddSon($son_id, $son_name, $son_age){
        $sonHandler = new Son($son_id, $son_name, $son_age);
        $sonHandler->setFather($this);
        $this->sons[] = $sonHandler;
        return $sonHandler;
    }
}

As a side note, I wouldn't create the son within the AddSon method, I would have that method take an already created son as its parameter.