Symfony service only initiated after method call - symfony

Question

I noticed that a Symfony service is only initiated (the constructor is executed), when a method in that service is called. This can be important if your service only has a constructor, and no methods.
For example:
class MyService {
public function __construct($someOtherService) {
$someOtherService->setFoo("bar");
}
}
// And of course put this service in services.yml
app.my_service:
class: AppBundle\...\MyService
arguments: [ app.some_other_service ]
In this case, the constructor and thus setFoo("bar") is not called. Why is this? Is it possible to somehow force the service to initiate, without calling a (dummy) method on this service?
I also tried to add "lazy: false" for the app.my_service, but that makes no difference.
I'm using Symfony 2.8.

Answer 1

your services are never instantiated if they are never used. to enforce instantiating service you can hook into any kind of event listeners that suits your event, when you want get service (i.e kernel.request) and pass this service as a dependency to listener. this will trigger service constructor first time the event is triggered during the container lifespan.
but i'd rather suggest you to review the architecture. having service with the constructor only is nonsense
Moreover, you can instantiate services on instantiation of EvendDispatcher (just because it would depend on you service) without firing events
listener sample:
class ServiceInstantiatorListener
{
public function onRequest(KernelEvent $kernel)
{
return; //noop, just make sure it works
}
public function instantiate($service)
{
return $service; // noop again, just call to pass service container argument
}
}
yaml config:
services:
my_app.service_instantiator_listener:
class: My\App\ServiceInstantiatorListener
tags:
- { 'name': 'kernel_events', 'event': 'kernel.request', 'method':'onRequest' }
calls:
- [instantiate, ["#my_app.weird_service_one"]]
- [instantiate, ["#my_app.weird_service_two"]]
Going further you can mark your services with tag and configurate calls dynamically with MyAppBundleExtension compiler passes
http://symfony.com/doc/current/service_container/tags.html#create-a-compiler-pass
I hope there are better ways to force instantiating services (i.e some container internal events), but currently I haven't met the case I need that.

Answer 2

You're describing the behaviour of a lazy-loaded service. Check the config for lazy: true and remove/disable it.
Symfony docs, lazy loaded service:
The actual class will be instantiated as soon as you try to interact with the service (e.g. call one of its methods).

Answer 3

You don't really need to call a dummy method on the service to initiate it.
You can instantiate the service object by using the following statement:
$this->container()->get('app.my_service');