Symfony2 Command and logging

gistfile1.php

    protected function execute(InputInterface $input, OutputInterface $output)
    {
        $fixtureDir = \APPLICATION_PATH . '/' . $input->getArgument('dir');
        if (!\is_dir($fixtureDir)) {
            throw new \Exception('The fixture dir `'.$fixtureDir.'` is not exist.');
        }

        $loader = new Loader();
        $loader->loadFromDirectory($fixtureDir);

        $executor = new ORMExecutor(\Zend_Registry::get('em'), new ORMPurger());
        $executor->setLogger(function($msg) use ($output) {
            $output->writeln($msg);
        });


        $executor->execute($loader->getFixtures());
    }