php class extends - attributes/methods with same name ok?

Question

If you have a class named "User" and another class named "Admin" that extends "User", and you want Admin to inherit all attributes,methods from User, except for the __construct method, for example.

class User {
private $name;

function __construct($name) {
$this->name = $name;
}
}

and

class Admin extends User {
private $authorization;

function __construct($name,$authorization) {
$this->name = $name;
$this->authorization = $authorization;
}
}

Is this correct? Does Admin override User's construct method? If the extending class has the same method name I suppose it's invalid. Am I totally missing the point of class extension?

Answer 1

Yes it's what extends is for. You can override all methods.

You can even use same named parent class inside method in child class.

See: http://www.php.net/manual/de/keyword.parent.php

Answer 2

It is not invalid. One aspect of class inheritance is, that you can override methods and provide another implementation.

But in your case, I would do

class Admin extends User {
    private $authorization;

    function __construct($name,$authorization) {
        parent::__construct($name);
        $this->authorization = $authorization;
    }
}

as you already implement the "name assignment" in the parent class. It is a cleaner approach.

Answer 3

No, this is perfectly legal as you are overriding User's constructor. Generally spoken, methods with similar names in extending class "override" their parent's.

Keep in mind though that modifiers do play a role here: "private" declared methods in a superclass won't get overridden as they aren't inherited by extending classes. "final" declared methods can't be overriden by extending classes - under no circumstances.