容器

每个 Slim 应用都有很多 依赖，比如在前面对象概念中所提到的环境、请求、响应以及路由器等对象。

Slim 为每个依赖都提供了可以直接使用的自身实现。但由于 Slim 应用本身是 Pimple 依赖注入容器的实例，你也可以注入自定义的依赖实现。Slim 应用的依赖都是通过具有延迟初始化特性的 Pimple 服务来实现的，只有在被调用时才会初始化并返回相应的对象。

服务（Services）

Slim 应用默认的依赖服务都是可以被覆写的，你只需要在调用 run() 方法之前注入对应的自定义 Pimple 服务即可。这些默认服务包括：

settings : 设置服务必须返回一个数组或者实现了 \ArrayAccess 接口的 共享 实例。

environment : 环境服务必须返回实现了 \Slim\Interfaces\Http\EnvironmentInterface 接口的 共享 实例。

request : 请求服务必须返回实现了 \Psr\Http\Message\RequestInterface 接口的新实例。

response : 响应服务必须返回实现了 \Psr\Http\Message\ResponseInterface 接口的新实例.

router : 路由器服务必须返回实现了 \Slim\Interfaces\RouterInterface 接口的 共享 实例。

errorHandler : This service must return a callable to be invoked if there is an application error. The callable MUST return an instance of \Psr\Http\Message\ResponseInterface. The callable SHOULD accept three arguments:

1. \Psr\Http\Message\RequestInterface
2. \Psr\Http\Message\ResponseInterface
3. \Exception

notFoundHandler : This service must return a callable to be invoked if the current HTTP request URI does not match an application route. The callable MUST return an instance of \Psr\Http\Message\ResponseInterface. The callable SHOULD accept two arguments:

1. \Psr\Http\Message\RequestInterface
2. \Psr\Http\Message\ResponseInterface

notAllowedHandler : This service must return a callable to be invoked if an application route matches the current HTTP request path but not its method. The callable MUST return an instance of \Psr\Http\Message\ResponseInterface. The callable SHOULD accept three arguments:

1. \Psr\Http\Message\RequestInterface
2. \Psr\Http\Message\ResponseInterface
3. Array of allowed HTTP methods

You most likely do not need to replace these dependencies. However, you can if necessary. Slim’s default service implementations live in the Slim application’s __construct() function.

服务提供者（Service providers）

Each Slim application extends the \Pimple\Container class. This means each Slim application can accept and register Pimple Service Providers. You register Pimple Service Providers with the Slim application’s register() method.

A simple example is the slim/twig-view component. After you install the slim/twig-view component with Composer, you can register the component with a Slim application like this:

// Create Slim app
$app = new \Slim\App();
// Register Twig View service
$app->register(new \Slim\Views\Twig('path/to/templates', [
    'cache' => 'path/to/cache'
]));
// Use Twig View service in route
$app->get('/hello/{name}', function ($request, $response, $args) {
    $this['view']->render('profile.html', [
        'name' => $args['name']
    ]);
})->setName('profile');
// Run app
$app->run();

The slim/twig-view service provider adds a new view service to the Slim application container that you can use to render Twig templates.