EventDispatcher Component
EventDispatcher implements a lightweight version of the Observer design pattern.
use Symfony\Component\EventDispatcher\EventDispatcher;
use Symfony\Component\EventDispatcher\Event;
$dispatcher = new EventDispatcher();
$dispatcher->addListener('event_name', function (Event $event) {
// ...
});
$dispatcher->dispatch('event_name');
Resources
You can run the unit tests with the following command:
$ cd path/to/Symfony/Component/EventDispatcher/
$ composer.phar install --dev
$ phpunit