Get instance of a Symfony2 class executed by an event - symfony

Question

I'm running some code by using an event listener:
namespace Acme\Bundle\NewBundle\EventListener;
use Symfony\Component\HttpKernel\Event\GetResponseEvent;
class RequestListener
{
public $value;
public function onKernelRequest(GetResponseEvent $event)
{
$this->value = 1;
}
}
I need to be able to access the class properties (just $value in my example) on these two occasions:
(a) In a normal controller executed from a route.
(b) From a Twig template (using the Twig render command). I don't want to pass anything in to Twig to do this as it's actioned on every request.
...how would I do this? I suppose I need to get the object's instance, but considering it was the event that created it, I can't see how.

Answer 1

The attributes field of the Request class is usually used for populating stuff to be used by other parts of the code. For example, one of the Symfony listeners sets the _route parameter in it.
You can get the request from the $event object:
$request = $event->getRequest();
$request->attributes->set('value', 1);
Then you would get it from a controller:
public function someAction(Request $request)
{
$value = $request->attributes->get('value');
// shorter but a bit less effective
$value = $request->get('value');
}
And in Twig:
{{ app.request.attributes.get('value') }}
Or shorter but a bit less effective:
{{ app.request.get('value') }}
P.S. It would actually be more effective if you asked what you're trying to solve instead of how. You might be coming up with a complicated nonidiomatic solution to a problem with a simple and common idiomatic solution.