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04.

Calling Parent Class Methods

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We covered that when you override a function, you override it entirely. In RebelShip we're overriding getNameAndSpecs:

44 lines | lib/Model/RebelShip.php
// ... lines 1 - 2
class RebelShip extends Ship
{
// ... lines 5 - 22
public function getNameAndSpecs($useShortFormat = false)
{
if ($useShortFormat) {
return sprintf(
'%s: %s/%s/%s (Rebel)',
$this->getName(),
$this->getWeaponPower(),
$this->getJediFactor(),
$this->getStrength()
);
} else {
return sprintf(
'%s: w:%s, j:%s, s:%s (Rebel)',
$this->getName(),
$this->getWeaponPower(),
$this->getJediFactor(),
$this->getStrength()
);
}
}
}

which means that when this method is called on a RebelShip object the getNameAndSpecs inside of the original Ship class, i.e. the parent class, is never called. In this case that's sort of a problem because it leaves us with all this code duplication. It would be way better if we could somehow call the parent method, getNameAndSpecs inside of Ship, and then just add this '(rebel)' part to the end.

We saw in the last chapter, that from within RebelShip you can call methods that exist in the parent class as long as they are public or protected. Let's try that here. Add $val = $this->getNameAndSpecs(). Pass in the $useShortFormatand then $val .= ('Rebel'); and finally return $val;:

31 lines | lib/Model/RebelShip.php
// ... lines 1 - 2
class RebelShip extends Ship
{
// ... lines 5 - 22
public function getNameAndSpecs($useShortFormat = false)
{
$val = $this->getNameAndSpecs($useShortFormat);
$val .= ' (Jedi)';
return $val;
}
}

Doesn't that look a whole lot nicer? Yes, yes it does.

Let's give our experiment here a try. Refresh! Hmmm something is wrong... (!) Fatal error: Maximum, let's view the source code since this error is stuck in our select box. Ah there we go: (!) Fatal error: Maximum function nesting level of '200' reached, aborting!. This means that we have a loop in our code, on index line 98 we call getNameAndSpecs and then on line 25 of RebelShip we call getNameAndSpecs again. This isn't working because when we call $this->getNameAndSpecs, it's literally calling this same method again inside of RebelShip not the parent function in Ship.

The parent Keyword

The way you get this to call the parent function is with a special key word called parent:::

31 lines | lib/Model/RebelShip.php
// ... lines 1 - 22
public function getNameAndSpecs($useShortFormat = false)
{
$val = parent::getNameAndSpecs($useShortFormat);
$val .= ' (Jedi)';
return $val;
}
// ... lines 30 - 31

Let's try this again in our browser, refresh, and checking our dropdown everything is working again. Except, maybe I could use a space here to make things look nicer. There we go.

Don't worry about this parent keyword too much it's used in exactly one situation calling: a parent function that you overrode.

We'll see this :: syntax again later when we talk about static things.