اگر construct به این صورت تعریف بشه هم به نظرم میتونه استراتژیمون تو ران تایم تغییر بکنه

    private $paymentStrategy;
    public function __construct(PaymentInterface $paymentStrategy)
    {
        $this->paymentStrategy = $paymentStrategy;
    }

و

$payment = new Payment(new OnlinePayment);
$payment->pay(10000);

تفاوتی داره با این که استاد پایین تعریف کرده داره؟

    private $paymentStrategy;
    public function __construct(PaymentInterface $paymentStrategy)
    {
        $this->setPaymentStrategy($paymentStrategy);
    }
    // To change strategy on runtime
    public function setPaymentStrategy(PaymentInterface $paymentStrategy)
    {
        $this->paymentStrategy = $paymentStrategy;
    }

و

$payment = new Payment(new OnlinePayment);
$payment->setPaymentStrategy(new OnlinePayment);
$payment->pay(10000);