.. note::

Whenever you are extending a (part of a) bundle, make sure that your bundle

is registered in the kernel **after** the bundle you're trying to override

parts of. Otherwise, your config that is supposed to override bundle

configuration, is instead overridden by it!

In order to completely override a service, just define the service as you would

usual, but making sure the id of the service is identical to the one you are

overriding.

In order to extend a service (e.g. just add a method, but leaving the

dependencies or tags intact), make sure the class name is defined as a parameter

in the service config of the bundle containing the service. You can then either

set this parameter in your config.yml, or, if you're going to reuse your bundle

and it should always override the class, in your bundle you can override the

class name by setting the parameter directly in the container in the Extension

class of your bundle:

.. code-block:: html+php

<?php

namespace Foo\BarBundle\DependencyInjection;

use Symfony\Component\Config\FileLocator;

use Symfony\Component\HttpKernel\DependencyInjection\Extension;

use Symfony\Component\DependencyInjection\Loader;

class FooBarExtension extends Extension

public function load(array $configs, ContainerBuilder $container)

$configuration = new Configuration();

$config = $this->processConfiguration($configuration, $configs);

$container->setParameter('parameter_name.containing.service_class', 'Foo\BarBundle\Service\Service');

$loader = new Loader\XmlFileLoader($container, new FileLocator(__DIR__.'/../Resources/config'));

$loader->load('services.xml');

If you want to do something beyond just overriding a parameter - like adding a

method call - it must be done as a compiler pass. See

`/cookbook/service_container/compiler_passes`