service_subscriber_trait.php

<?php

class Foo implements ServiceSubscriberInterface
{
    use ServiceSubscriberTrait;
  
    public function do()
    {
        $this->getRouter();
    }

    private function getRouter(): RouterInterface
    {
        return $this->container->get(__FUNCTION__);
    }
}

trait ServiceSubscriberTrait
{
    private $container;

    public function setContainer(ContainerInterface $container)
    {
        $this->container = $container;
    }

    public static function getSubscribedServices()
    {
        $r = new \ReflectionClass(static::class);
      
        // detect methods, autowire and define services with functions names in the current service locator
        // ...
    }
}