symfony/symfony-docs — pull request #1679 by MattKetmo (2012-09-03 19:40:59+00:00)
Title: Use useAttributeAsKey before the prototype method

The `useAttributeAsKey()` method must be used before `prototype()`.

Example https://github.com/symfony/symfony/blob/master/src/Symfony/Bundle/FrameworkBundle/DependencyInjection/Configuration.php#L324,