PHP框架如何复用代码？Traits与Service模式详解

trait Loggable
{
    public function log($message)
    {
        file_put_contents('app.log', date('Y-m-d H:i:s') . ' - ' . $message . "\n", FILE_APPEND);
    }
}

class UserService
{
    use Loggable;
public function createUser($data)
{
    // 处理用户创建逻辑
    $this->log('User created: ' . $data['name']);
}
}

class OrderService
{
    public function placeOrder($userId, $items)
    {
        // 扣减库存
        $this->decreaseStock($items);
        // 计算积分
        $this->awardPoints($userId, $items);
        // 发送通知
        $this->sendNotification($userId);
    return ['status' => 'success'];
}

private function decreaseStock($items) { /* ... */ }
private function awardPoints($userId, $items) { /* ... */ }
private function sendNotification($userId) { /* ... */ }
}

class OrderController extends Controller
{
    public function store(Request $request)
    {
        $service = new OrderService();
        return $service->placeOrder($request->user()->id, $request->items);
    }
}

trait Cacheable
{
    protected function cacheGet($key, $callback)
    {
        if (isset($_SESSION[$key])) {
            return $_SESSION[$key];
        }
        $data = $callback();
        $_SESSION[$key] = $data;
        return $data;
    }
}
class ProductService
{
use Cacheable;
public function getList()
{
    return $this->cacheGet('product_list', function () {
        return Product::all();
    });
}
}