Symfony\Component\Form\FormBuilder::getFormFactory PHP Method

    public function getFormFactory()
    {
        return $this->factory;
    }

 public function buildForm(FormBuilder $builder, array $options)
 {
     $factory = $builder->getFormFactory();
     //    throw new \Exception('El valor de region es '.$regionId);
     $builder->add('nombre')->add('apellido');
     if (null == $options['data']->getId()) {
         $builder->add('login')->add('password', 'password', array('required' => true));
     } else {
         $builder->add('login', null, array('read_only' => true))->add('password', 'password', array('required' => false));
     }
     $builder->add('rut')->add('cargo')->add('profesion')->add('especialidades')->add('email')->add('email2')->add('codigoPostal')->add('direccion')->add('telefono')->add('telefono2')->add('celular')->add('empresa')->add('paginaWeb')->add('tipoUsuario', null, array('required' => true, 'preferred_choices' => array(5)));
     /*        
               if (null == $options['data']->getRegion()) {
                  $builder->add('comuna', null , array('required' => false, 'empty_value' => '...', 'choices' => array()));       
               } else {           
                   $builder->add('comuna', 'entity', array(
                                   'required' => false,
                                   'class' => 'TipddyMasleadsBundle:Comunas',
                                   'empty_value' => 'Seleccione una comuna',
                                   'query_builder' => function(EntityRepository $repository) use ($regionId) {
                                           return $repository->createQueryBuilder('c')
                                                             ->where('c.region = :region')
                                                             ->setParameter('region', $regionId)
                                                             ->orderBy('c.id', 'ASC');
                                   }));
                  }
     */
     $builder->add('region', null, array('empty_value' => 'Seleccione', 'required' => false));
     /* Probando Eventos en Formularios */
     $factory = $builder->getFormFactory();
     $refreshComuna = function ($form, $region) use($factory) {
         $form->add($factory->createNamed('entity', 'comuna', null, array('class' => 'TipddyMasleadsBundle:Comunas', 'empty_value' => $region == null ? '...' : 'Seleccione', 'label' => 'register.comuna.label', 'query_builder' => function (EntityRepository $repository) use($region) {
             return $repository->createQueryBuilder('c')->where('c.region = :region')->setParameter('region', $region)->orderBy('c.id', 'ASC');
         })));
     };
     $builder->addEventListener(FormEvents::PRE_SET_DATA, function (DataEvent $event) use($refreshComuna) {
         $form = $event->getForm();
         $data = $event->getData();
         if ($data == null) {
             $refreshComuna($form, null);
         }
         if ($data instanceof Usuarios) {
             $refreshComuna($form, $data->getRegion());
         }
     });
     $builder->addEventListener(FormEvents::PRE_BIND, function (DataEvent $event) use($refreshComuna) {
         $form = $event->getForm();
         $data = $event->getData();
         if (array_key_exists('region', $data)) {
             $refreshComuna($form, $data['region']);
         }
     });
 }