理解PHP trait DTO的核心概念与特性

trait DTO {
    protected $data = [];

    public function set($key, $value) {
        $this->data[$key] = $value;
    }

    public function get($key) {
        return $this->data[$key] ?? null;
    }
}

class User {
    use DTO;

    public function getUserInfo() {
        $name = $this->get("name");
        $age = $this->get("age");

        return "Name: $name, Age: $age";
    }
}

class Order {
    use DTO;

    public function getOrderInfo() {
        $productId = $this->get("productId");
        $quantity = $this->get("quantity");

        return "Product ID: $productId, Quantity: $quantity";
    }
}

$user = new User();
$user->set("name", "John Doe");
$user->set("age", 25);
echo $user->getUserInfo();  // 输出：Name: John Doe, Age: 25

$order = new Order();
$order->set("productId", "123456");
$order->set("quantity", 3);
echo $order->getOrderInfo();  // 输出：Product ID: 123456, Quantity: 3