PHP面向对象开发：解决父类构造器参数在嵌套子对象方法中丢失的问题

// 原始问题代码示例

class Form extends Controller
{
    public function __construct()
    {
        // Form类调用父类Controller的构造函数，传入视图路径
        parent::__construct(__DIR__ . "/../../../themes/" . THEME . "/pages/");
    }
}

class Controller
{
    /** @var View */
    protected $view;

    public function __construct(string $pathToViews = null)
    {
        // Controller构造函数接收路径，并用它初始化View对象
        $this->view = new View($pathToViews);
        var_dump("Controller __construct 内部路径: " . $pathToViews); // 此处路径显示正确
    }
}

class View
{
    protected $pathToViews;

    public function __construct(string $pathToViews = null)
    {
        $this->pathToViews = $pathToViews;
    }

    public function show($viewName, $data = [])
    {
        // 尝试在View的show方法中访问路径，却可能显示null
        var_dump("View show 方法内部路径: " . $this->pathToViews);
    }
}

// 假设外部代码这样调用（这可能是问题的根源）
// $form = new Form();
// $newView = new View(); // 错误：这里创建了一个新的View实例
// $newView->show('some_view'); // 这个新实例的$pathToViews将是null

class Controller
{
    /** @var View */
    protected $view;

    public function __construct(string $pathToViews = null)
    {
        $this->view = new View($pathToViews);
        echo "Controller __construct 内部路径: " . ($pathToViews ?? 'null') . "\n";
    }

    /**
     * 获取Controller内部的View实例
     * @return View
     */
    public function getView(): View
    {
        return $this->view;
    }
}

class View
{
    protected $pathToViews;

    public function __construct(string $pathToViews = null)
    {
        $this->pathToViews = $pathToViews;
    }

    public function show($viewName, $data = [])
    {
        echo "View show 方法内部路径: " . ($this->pathToViews ?? 'null') . "\n";
    }
}

// 模拟Form类调用Controller的场景
// 假设Form的构造函数会调用parent::__construct()并传入路径
// 这里直接实例化Controller以简化演示
$controller = new Controller('path/to/my/views');

// 获取Controller内部的View实例
$viewInstance = $controller->getView();

// 通过正确的View实例调用show方法
$viewInstance->show('home');

// 预期输出:
// Controller __construct 内部路径: path/to/my/views
// View show 方法内部路径: path/to/my/views

class Controller
{
    /** @var View */
    protected $view;

    /**
     * Controller构造函数通过依赖注入接收View实例
     * @param View $view 外部注入的View实例
     * @param string|null $pathToViews 视图路径，如果需要通过Controller设置
     */
    public function __construct(View $view, string $pathToViews = null)
    {
        $this->view = $view;
        // 如果路径需要由Controller设置，则调用View的setter方法
        if ($pathToViews !== null) {
            $this->view->setPathtoViews($pathToViews);
        }
        echo "Controller __construct 内部路径: " . ($pathToViews ?? 'null') . "\n";
    }

    /**
     * 依然可以提供getter，但通常直接使用注入的实例
     * @return View
     */
    public function getView(): View
    {
        return $this->view;
    }
}

class View
{
    protected $pathToViews;

    /**
     * 提供一个setter方法来设置视图路径
     * @param string $pathToViews
     */
    public function setPathtoViews(string $pathToViews)
    {
        $this->pathToViews = $pathToViews;
    }

    public function show($viewName, $data = [])
    {
        echo "View show 方法内部路径: " . ($this->pathToViews ?? 'null') . "\n";
    }
}

// 示例使用：外部创建并注入依赖
$viewInstance = new View(); // 外部创建View实例

// 实例化Controller，注入View实例和路径
$controller = new Controller($viewInstance, 'path/to/injected/views');

// 直接通过外部创建的View实例调用方法
$viewInstance->show('product_detail');

// 也可以通过Controller获取（如果Controller有其他逻辑需要View）
$controller->getView()->show('about_us');

// 预期输出:
// Controller __construct 内部路径: path/to/injected/views
// View show 方法内部路径: path/to/injected/views
// View show 方法内部路径: path/to/injected/views