method returns unexpected result

[johnmerlino]

Why does this return null rather than 'john must write the book'?

<?
abstract class User {
	protected $name;
	protected $role;

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

	abstract function run_errand();
}

class Author extends User {	
	public function run_errand(){
		echo $this->name . "must write the book";
	}
}

class Editor extends User {
	public function run_errand(){
		echo $this->name . "must edit the book";
	}
}

class Boss {
	private $users = array();

	public function review(User $user){
		$this->user[] = $user;
	}

	public function delegate(){
		if(count($this->users)){
			foreach($this->users as $user){
				if($user->role == "author"){
					echo $user->run_errand();
				}
			}
		}
	}
}

//client code
$boss = new Boss();
$boss->review(new Author('John','author'));
var_dump($boss->delegate()); //returns null
?>

[requinix]

Because delegate() isn't returning anything.

 

If you're wondering why you don't get any output it's because you use "user" in one place and "users" in the others.

[johnmerlino]

user is only a local variable in the foreach loop that refers to users, because $this->users is an array of users, so we iterate through them one at a time. Sure that's the issue?

[requinix]

Er, not that one.

class Boss {
private $USERS = array();

public function review(User $user){
	$this->USER[] = $user;
}

That one.

 

(Too bad I can't put highlighting in code tags...)

[johnmerlino]

Thanks for response. Why did PHP not thrown an exception error "undefined variable $user on line such and such". The backtrace should have caught that one. Or can you create properties on the fly in PHP? If so, that sucks because that will happen a lot.

[requinix]

Or can you create properties on the fly in PHP?

Yup.