Feature: #84112 - Symfony dependency injection for core and extbase¶

# Configuration/Services.yaml
services:
  _defaults:
    autowire: true
    autoconfigure: true
    public: false

  Your\Namespace\:
    resource: '../Classes/*'

# Configuration/Services.yaml
services:
  _defaults:
    autoconfigure: false
    public: false

  Your\Namespace\Service\ExampleService:
   # mark public – means this service should be accessible from $container->get()
   # and (often more important), both GeneralUtility::makeInstance() and the Extbase
   # ObjectManager will be able to use the Symfony DI managed service
   public: true
   # Defining a service to be shared is equal to TYPO3's SingletonInterface behaviour
   shared: true
   # Configure constructor arguments
   arguments:
     $siteConfiguration: '@TYPO3\CMS\Core\Configuration\SiteConfiguration'

  # Example Extbase controller
  Your\Namespace\Controller\ExampleController:
   # mark public to be dispatchable
   public: true
   # Defining to be a prototype, as Extbase controllers are stateful (i. e. could not be defined as singleton)
   shared: false
   # Configure constructor arguments
   arguments:
     $exampleService: '@Your\Namespace\Service\ExampleService'

# Configuration/Services.php
<?php
declare(strict_types = 1);
namespace Your\Namespace;

use Symfony\Component\DependencyInjection\ContainerBuilder;
use Symfony\Component\DependencyInjection\Loader\Configurator\ContainerConfigurator;

return function (ContainerConfigurator $container, ContainerBuilder $containerBuilder) {
    $containerBuilder->registerForAutoconfiguration(MyCustomInterface::class)->addTag('my.custom.interface');

    $containerBuilder->addCompilerPass(new DependencyInjection\MyCustomPass('my.custom.interface'));
};

# Classes/DependencyInjection/MyCustomPass.php
<?php
declare(strict_types = 1);
namespace Your\Namespace\DependencyInjection;

use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use Your\Namespace\MyRegistry;

final class MyCustomPass implements CompilerPassInterface
{
    public function process(ContainerBuilder $container)
    {
        $myRegistry = $container->findDefinition(MyRegistry::class);

        foreach ($container->findTaggedServiceIds('my.custom.interface') as $id => $tags) {
            $definition = $container->findDefinition($id);
            if (!$definition->isAutoconfigured() || $definition->isAbstract()) {
                continue;
            }

            // Services that implement MyCustomInterface need to be public,
            // to be lazy loadable by the registry via $container->get()
            $container->findDefinition($id)->setPublic(true);
            // Add a method call to the registry class to the (auto-generated) factory for
            // the registry service.
            // This supersedes explicit registrations in ext_localconf.php (which're
            // still possible and can be combined with this autoconfiguration).
            $myRegistry->addMethodCall('registerMyCustomInterfaceImplementation', [$id]);
        }
    }
}