Symfony\Component\DependencyInjection\DefinitionDecorator::setFactoryClass PHP Method

    public function setFactoryClass($class)
    {
        $this->changes['factory_class'] = true;

        return parent::setFactoryClass($class);
    }

 /**
  * {@inheritdoc}
  */
 public function load(array $configs, ContainerBuilder $container)
 {
     $configuration = new Configuration();
     $config = $this->processConfiguration($configuration, $configs);
     $loader = new Loader\YamlFileLoader($container, new FileLocator(__DIR__ . '/../Resources/config'));
     $loader->load('services.yml');
     foreach ($config['connections'] as $name => $values) {
         $def = new Definition();
         $def->setClass($container->getParameter('agentsib_sphinx.connection.class'));
         $params = array('host' => $values['host'], 'port' => $values['port']);
         if ($values['socket']) {
             $params['socket'] = $values['socket'];
         }
         $def->setArguments(array($name, $values['driver'], $params));
         $def->addMethodCall('addLogger', array(new Reference('agentsib_sphinx.logger')));
         $container->setDefinition(sprintf('agentsib_sphinx.%s.connection', $name), $def);
         $helperDef = new DefinitionDecorator('agentsib_sphinx.factory.helper');
         $helperDef->setFactoryClass($container->getParameter('agentsib_sphinx.helper.class'));
         $helperDef->setFactoryMethod('create');
         $helperDef->addArgument(new Reference(sprintf('agentsib_sphinx.%s.connection', $name)));
         $helperDef->setPublic(true);
         $container->setDefinition(sprintf('agentsib_sphinx.%s.helper', $name), $helperDef);
         if ($name == $config['default_connection']) {
             $container->setAlias('agentsib_sphinx.connection', sprintf('agentsib_sphinx.%s.connection', $name));
             $container->setAlias('agentsib_sphinx.helper', sprintf('agentsib_sphinx.%s.helper', $name));
         }
     }
 }