because by default, config files hasn't namespace declared. Config parser can read string
'__NAMESPACE__'
and determine correctly the namespace.
If you want to use it without quotes, you can declare in your config file :
namespace Application;
and use __NAMESPACE__
without quote.
That's why you can see sometimes in tutorials for Doctrine config's sample like :
'doctrine' => array(
'driver' => array(
'application_entity' => array(
'class' => 'Doctrine\ORM\Mapping\Driver\AnnotationDriver',
'paths' => __DIR__ . '/../src/' . __NAMESPACE__ . '/Entity',
),
'orm_default' => array(
'drivers' => array(
__NAMESPACE__ . '\Entity' => 'application_entity',
)
)
)
),