To me it looks very close to the issue solved by the autowiring... What is the issue you are trying to solve? (at least I think that a big part of the code could be shared)

as @Nicofuma said, this is very close to what does autowiring and makes the container even bigger... so I'd say 👎 as is.

What can be nice instead is an utility class returning the list of services of a given type. (This class can be used internally by the autowiring system and in external bundles needing such features).

$em = $this->get(RegistryInterface::class)->getManager(); looks acutally quite neat, but maybe i am missing something

@backbone87 it is indeed attractive.

To prevent any confusion, why not introducing a new method returning a list of all services of a given type:

$container->getOfType(RegistryInterface::class); // the instance of the service of the given type, throw an exception if there is several services of this type
$container->getAllOfType(RegistryInterface::class); // an array of services having the given type

@dunglas And why introduce a new method (compare it with http://php-di.org/)? What is use case of the public method $container->getAllOfType(RegistryInterface::class);?

@Ener-Getick @Nicofuma Autowiring is only a special application of FQCN services. Symfony supports this feature for autowired services, but you can't make a reference to service by its type manually. That's inconsistent behavior.

A new method because it doesn't do the same thing: get retrieves a service by its name, getOfType retrieves a service by one of its types (SOLID code).

getAllOfType can be handy to retrieve all your entity managers, or all your elastica finders for instance, or all your API Platform data providers. I can think to a lot of usages.

@dunglas The service name can be string or FQCN. The string is alias for FQCN and vice versa.

services:
    Twig_Environment:
        class: Twig_Environment

    twig:
        alias: Twig_Environment

What is the correct call, $container->get(Twig_Environment::class) or $container->getOfType(Twig_Environment::class)?

Mentioned reasons for the method getAllOfType() are solved by tags.

It would also be nice to make getAllOfType return the service identifiers as keys of the returned array.

I opened #18300 which is an alternative approach using the methods @dunglas proposed (and one more: getServiceIdsOfType).
This also replaces the utility class described by @dunglas.

The DI container is not a service locator and should not be
This leans over this limit to me (also getAllOfType, getOfType, etc.)
👎 as well.

@nicolas-grekas what do you think about the utility class I introduced in #18300 (i changed my mind and decided to create a new class instead of introducing this kind of methods in the container, see #18300 (comment), it's only possible to use it at compilation not at runtime) ?

@nicolas-grekas Exactly! This PR is introducing automatic registration of service aliases. It has nothing to do with a service locator.

I created the https://github.com/symfonette/class-named-services library.

I thinks this is solved by #21133, isn't it?

@TomasVotruba yes, actually it's been working for a while already #21133 just made it easier. There is this however that's still missing and might be interesting:

# routing.yml
index:
  path: /
  defaults:
    _controller: 'AppBundle\Controller\MyController:index'

Closing then, thanks @hason