Symfony2, autoload service in service

Question

Question is simple but... So we have main service:

class ManagerOne {}

and have several another services we want to use in main service:

class ServiceOne{}
class ServiceTwo{}
class ServiceThree{}
class ServiceFour{}
...

Each named as (in services.yml)

service.one
service.two
service.three
service.four
...

Locations of services is different, not in one folder (but I don't think it's a huge trouble for custom autoloader).

Regarding manual we can inject them via __construct() in main service (ManagerOne) but what if we got 20 such services need to be injected? Or use only that we need. Describe them in services as simple inject? O.o I think it's not good idea so.... Also we can inject container and that's it. BUT! Everywhere people saying that inject container worst solution.

What I want. I need method for ManagerOne service which will load service i need by 'service.name' or 'path' with checker 'service exist'.

Answer 1

You could use service tagging and tag each service you want to use in your ManagerOne class. And either use constructor dependency injection or method injection.

Example:

First of all you need a compiler pass to collect your tagged services:

namespace ...\DependencyInjection\Compiler;

use Symfony\Component\DependencyInjection\Compiler\CompilerPassInterface;
use Symfony\Component\DependencyInjection\Reference;
use Symfony\Component\DependencyInjection\ContainerBuilder;

class ExamplePass implements CompilerPassInterface
{

    public function process(ContainerBuilder $container)
    {
        if (!$container->hasDefinition("manager.one")) {
            return;
        }
        $services = array();
        foreach ($container->findTaggedServiceIds('managed_service') as $serviceId => $tag) {
            $alias = isset($tag[0]['alias'])
                ? $tag[0]['alias']
                : $serviceId;

            // Flip, because we want tag aliases (= type identifiers) as keys
            $services[$alias] = new Reference($serviceId);
        }
        $container->getDefinition('manager.one')->replaceArgument(0, $services);
    }
}

Then you need to add the compiler pass to your bundle class:

namespace Example\ExampleBundle;

use Symfony\Component\HttpKernel\Bundle\Bundle;
use Symfony\Component\DependencyInjection\ContainerBuilder;
use ...\DependencyInjection\Compiler\ExamplePass;

class ExampleBundle extends Bundle
{
    public function build(ContainerBuilder $container)
    {
        parent::build($container);
        $container->addCompilerPass(new ExamplePass());
    }
}

Now you can use your services:

# services.yml
manager.one:
    class: ManagerClass
    arguments:
        - [] # will be replaced by our compiler pass

services.one:
    class: ServiceOne
    tags:
        - { name: managed_service, alias: service_one }

services.two:
    class: ServiceTwo
    tags:
        - { name: managed_service, alias: service_two }

But caution if you get your manager, all service classes will be automatically created. If this is a performance drawback for you could pass only the service ids (not the Reference) to your management class. Add the @service_container as second argument and create the service as needed.