Question

Just a quick question, wondering if objects retrieved from the service container in Symfony2 are returned by reference or as a copy?

The reason I ask is because I want to know if I do something like:

public function helloAction()
{
    $mailer = $this->get('acme.mailer');
    $mailer->shutdown();
}

in a controller, and the shutdown() method does something internally to the object, will the acme.mailer service be “shutdown” in the container?

In other words, can I alter a service permanently after getting it from the container? Is this good practice?

Thanks

Answer 1

Services are returned by reference just like all PHP objects (by default).

It doesn’t mean you will always get the same instance of a given service though.

Each service is defined in a scope. DependencyInjection container provides two generic scopes:

• container – each time you request a service you’re getting the same instance
• prototype – each time you request a service you’re getting a new instance

Container scope is the default one.

Note: Symfony introduces additional scopes.

Learn more about scopes from the official documentation: How to work with Scopes

To answer second part of the question. If a service is defined in a container scope I don’t think it’s a good idea to destroy it in the controller. Other parts of your application might still be needing it. I’d rather perform shutdown in a destructor.