Optimizing service consumption with Service Subscription. Moved a ser…

…vice with several optional dependencies to a separate package.

packages/acme-image/src/ImageService.php

@@ -3,15 +3,41 @@
 
 namespace Acme\Image;
 
+use Acme\Storage\{Cloudinary,File,S3};
+use Psr\Container\ContainerInterface;
+use Symfony\Contracts\Service\ServiceSubscriberInterface;
+
 /**
- * Empty ImageService
+ * Class ImageService provides an API for the application.
+ * It is a bridge registered as a service assisting decoupling the module
+ * to change it independently from the service API.
  *
  * @package Acme\Image
  * @api
  */
-final class ImageService
+final class ImageService  implements ServiceSubscriberInterface
 {
-    public function __construct()
+    public function __construct(private ContainerInterface $locator)
+    {
+    }
+
+    /**
+     * @see https://symfony.com/doc/current/service_container/service_subscribers_locators.html
+     * @return string[]
+     */
+    public static function getSubscribedServices(): array
+    {
+        return [ File::class, S3::class, Cloudinary::class ];
+    }
+
+    public function store($type,$file)
     {
+        //Select a storage solutions based on purpose
+        $storage = match ($type) {
+            'avatar' => $this->locator->get(File::class),
+            'post' => $this->locator->get(S3::class),
+            default => $this->locator->get(Cloudinary::class),
+        };
+        $storage->store($file);
     }
 }

public/index.php

@@ -1,10 +1,25 @@
 <?php
 
 include '../vendor/autoload.php';
+use Symfony\Component\Config\FileLocator;
+use Symfony\Component\DependencyInjection\ContainerBuilder;
+use Symfony\Component\DependencyInjection\Loader\PhpFileLoader;
 
+// Usually an application kernel creates
+// an IoC-container, routing, middleware, controllers,
+// but for the demo I'll create a container and a controller.
+
+$containerBuilder = new ContainerBuilder();
+$loader = new PhpFileLoader($containerBuilder, new FileLocator('..'));
+$loader->load('services.php');
+$containerBuilder->compile();
+// in a real project there will be some cacheing of the compiled container
 
 try {
-    $controller = new \Acme\ImageController;
+    /**
+     * @var \Acme\ImageController $controller
+     */
+    $controller = $containerBuilder->get(\Acme\ImageController::class);
 } catch (Exception $e) {
     echo $e->getMessage(),"\n",$e->getTraceAsString();
     exit;

services.php

@@ -2,9 +2,18 @@
 
 namespace Symfony\Component\DependencyInjection\Loader\Configurator;
 
+use Acme\Image\ImageService;
+use Acme\ImageController;
+
 return function(ContainerConfigurator $configurator) {
     /**
      * @see https://symfony.com/doc/current/service_container/autowiring.html
      */
     $services = $configurator->services()->defaults()->autowire()->public();
+
+    $services->set(ImageService::class)->tag('container.service_subscriber');
+
+    $services->set(ImageController::class);
+
+    $services->load('Acme\\Storage\\', './src/Storage/*');
 };

src/ImageController.php

@@ -2,13 +2,12 @@
 
 namespace Acme;
 
+use Acme\Image\ImageService;
+
 class ImageController
 {
-    private ImageLib $imageLib;
-
-    public function __construct()
+    public function __construct(private ImageService $imageLib)
     {
-        $this->imageLib = new ImageLib();
     }
 
     public function upload()

src/Storage/File.php

@@ -5,5 +5,7 @@
 class File
 {
     public function store()
-    {}
+    {
+        echo 'file stored';
+    }
 }