Question

I would like to have my abstract parent class have a method that would be inherited by a subclass which would allow that subclass to iterate through all of it’s variables (both the variables inherited from the parent, and it’s own variables).

At the moment if I implement this method in the parent, then only the parent’s variables will be iterated over:

class MyObject {

    private $one;
    private $two;
    private $three;

    function assignToMembers() {
        $xx = 1;
        foreach($this as $key => $value) {
            echo "key: ".$key."<br />";
            $this->$key = $xx;
            $xx++;
        }
    }

    public function getOne() {
        return $this->one;
    }

    public function getTwo() {
        return $this->two;
    }

    public function getThree() {
        return $this->three;
    }
}

class MyObjectSubclass extends MyObject {

    private $four;
    private $five;

    public function getFour() {
        return $this->four;
    }

    public function getFive() {
        return $this->five;
    }
}
$o = new MyObjectSubclass();
$o->assignToMembers();
echo $o->getOne()." ";
echo $o->getTwo()." ";
echo $o->getThree()." ";
echo $o->getFour()." ";
echo $o->getFive()." ";

// This prints 1 2 3

On the other hand, if I put the assignToMembers function in the subclass, then only the subclass’s members are iterated over.

Because I want my assignToMembers() function to be usable by a number of subclasses, I don’t want to have to implement it in every one, only in the parent class, but it looks like I will have to unless it can access that class’s members.

Is there any way to acheive this?

Thanks in advance.

Answer 1

You’ll need to use protected if you want your code to work as described. Remember the roles of the access/visibility modifiers:

• private – class level only access
• protected – whole inheritance chain access
• public – universal access