services.yml

# example 1: add a tag or a setter based on implemented interfaces:

services:
  _instanceof:
    Psr\Log\LoggerAwareInterface:
      calls:
         - [setLogger, ['@logger']]
    Symfony\Component\EventDispatcher\EventSubscriberInterface:
      tags: [kernel.event_subscriber]

  App\:
    psr4: ../src/{Foo,Bar}
    autowire: true

#  example 2: mark only some services as public

services:
  _instanceof:
    App\Foo:
      public: true
      
  App\:
    psr4: ../src/
    public: false