Hand-writen DI Container

config.php

<?php

namespace My;

return [
    'dependencies' => [
        //Domain
        TodoRepository::class => TodoRepositoryFactory::class,
        UserRepository::class => UserRepositoryFactory::class,
        //Infrastructure
        EventStore::class => EventStoreFactory::class,
        EventBus::class => EventBusFactory::class,
        CommandBus::class => CommandBusFactory::class,
        QueryBus::class => QueryBusFactory::class,
        ProjectionManager::class => ProjectionManagerFactory::class,
        'db.connection.default' => [DbConnectionFactory::class, 'db'],
        'db.connection.read' => [DbConnectionFactory::class, 'db'],
        MailSender::class => MailSenderFactory::class,
    ],
];

Dependencies.php

<?php

declare(strict_types=1);

namespace My;

use Psr\Container\ContainerInterface;

final class Dependencies implements ContainerInterface
{
    /** @var ArrayObject */
    private $config;

    /** @var array */
    private $factories;

    /** @var object[] */
    private $shared = [];

    public function __construct(ArrayObject $config)
    {
        $this->config = $config;

        $this->factories = $config['dependencies'];
        $this->factories['config'] = function () {
            return $this->config;
        };
    }

    public function get($id)
    {
        $factory = $this->getFactory($id);

        if (null === $factory) {
            throw DependencyNotFound::forId($id);
        }

        if ($this->shouldShare($id)) {
            return $this->share($id, $factory);
        }

        return $factory($this, $id);
    }

    public function has($id): bool
    {
        return isset($this->factories[$id]);
    }

    public function config(): ArrayObject
    {
        return $this->config;
    }

    public function todoRepository(): TodoRepository
    {
        return $this->get(TodoRepository::class);
    }

    public function userRepository(): UserRepository
    {
        return $this->get(UserRepository::class);
    }

    private function getFactory(string $id): ?callable
    {
        if (! isset($this->factories[$id])) {
            return null;
        }

        if (\is_string($this->factories[$id])) {
            $factoryClass = $this->factories[$id];
            $factory = new $factoryClass();
            $this->factories[$id] = $factory;
        }

        return $this->factories[$id];
    }

    private function shouldShare(string $id): bool
    {
        return !isset($this->config['shared_dependencies'][$id]) || true === $this->config['shared_dependencies'][$id];
    }

    private function share(string $key, callable $factory)
    {
        if (!array_key_exists($key, $this->shared)) {
            $this->shared[$key] = $factory($this, $key);
        }

        return $this->shared[$key];
    }
}