PHP通过类传递对象？

Question

After restructuring my entire class layout, I'm still having trouble using multiple class instances.

class User {
    public $variable;
    public function getUser() {
        $this->variable = 'It works!';
        return 'bob';
    }
}

class Base {}
class One extends Base {
    public function test() {
        print_r($User->variable); // Want it to print 'It works!'
    }
}

$User = new User();
$username = $User->getUser();
if($username === 'bob') {
    $One = new One();
    $One->test(); // prints "Notice: Undefined property: One::$variable
}

What the above code does: The class User gets the username. If the username is bob , it will create an object one and try to print the variable from class User . In my real code, User is extremely intricate and passing a bunch of things with __construct just isn't what I'm looking for.

I think the solution ( which is why I titled this question as so ) would be to create a new class User within class Base but I just can't wrap my head around having to create a whole new object and re-initiate everything just to get the username.

Answer 1

Inject your User instance:

class One {
    private $user;
    public function __construct(User $user) {
        $this->user = $user;
    }
    public function test() {
        print_r($this->user->variable);
    }
}

$User = new User();
$One = new One($user);
$One->test();

This doesn't have any undue effects with regards to efficiency, as the instance is passed by reference as opposed to copied.

Answer 2

The class One does not know about the $User variable and therefore can not access it.

You could either pass the variable to the class in the constructor or set it after creation of an object of the class.

class One extends Base {
    protected $user;
    public function setUser(User $user) {
        $this->user = $user;
    }
    public function One(User $user) {
        $this->setUser($user);
    }
    public function test() {
        print_r($this->user->variable);
    }
}

Or (but please don't, it is bad practice) set the $User variable to global.

global $User