Why use a return when calling parent? - php

Question

I am learning OO PHP and I was experimenting with using a parent::method in a child class. I noticed i had to use an "extra" return for the output of the parent method to show up. Could someone explain me why this is?
This is the code I used and in the code I made a comment.
class ShopProduct {
public $productnumber;
public function __construct($productnumber) {
$this->productnumber = $productnumber;
}
public function getSummary(){
return $this->productnumber;
}
}
class BookProduct extends ShopProduct {
public function __construct($productnumber) {
parent::__construct($productnumber);
}
public function getSummary() {
return parent::getSummary(); // if i dont use return it doesnt work? why is that?
// parent::getSummary(); is not enough it seems.
}
}
$product = new BookProduct(11111);
echo $product->getSummary();
?>

Answer 1

public function getSummary() {
return parent::getSummary(); // if i dont use return it doesnt work? why is that?
// parent::getSummary(); is not enough it seems.
}
Replace parent::getSummary() with any other function or method call:
public function getSummary() {
foo();
}
Of course you wouldn't expect getSummary to return anything in this case, right? Just because the method you're calling is parent::... doesn't change anything about this behaviour. It does not return automagically, because you may want to do something like this:
public function getSummary() {
$summary = parent::getSummary();
return "Book: $summary";
}
BTW, if the only thing your method does is call its parent, you can leave out the entire method. In other words, this:
class BookProduct extends ShopProduct {
public function __construct($productnumber) {
parent::__construct($productnumber);
}
public function getSummary() {
return parent::getSummary();
}
}
is exactly the same as this:
class BookProduct extends ShopProduct { }