PHP：将对象实例化为类的属性

Question

i have the line of codes:

class foo{
    public $object = new bar(2);

    public function index(){
        dd($this->object);
    }
}

and the bar object contains:

class bar{
    protected $number;

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

now its throwing me Constant expression contains invalid operation

Answer 1

It's not currently possible to instantiate an object during class properties declaration. That should be done in the object constructor instead :

class foo{
    public $object;

    public function __construct() {
        $this->object = new bar(2);
    }

    public function index(){
        dd($this->object);
    }
}