A very simple example using the Symfony EventDispatcher component.

SymfonyEventDispatcherExample.php

<?php

use Symfony\Component\EventDispatcher\Event;
use Symfony\Component\EventDispatcher\EventDispatcher;
use Symfony\Component\EventDispatcher\EventSubscriberInterface;

class MyListener
{

    public function onFooAction(Event $event)
    {
        echo __CLASS__ . '/' . __METHOD__;
        echo "<br>";
    }

}

class MySubscriber implements EventSubscriberInterface
{

    public static function getSubscribedEvents()
    {
        return [
            'foo.action' => ['onFooAction', 0],
            'bar.action' => ['onBarAction', 0],
            'baz.action' => ['onBazAction', 0]
        ];
    }

    public function onFooAction()
    {
        echo __CLASS__ . '/' . __METHOD__;
        echo "<br>";
    }

    public function onBarAction()
    {
        echo __CLASS__ . '/' . __METHOD__;
        echo "<br>";
    }

    public function onBazAction()
    {
        echo __CLASS__ . '/' . __METHOD__;
        echo "<br>";
    }

}

$dispatcher = new EventDispatcher();

$listener = new MyListener();
$dispatcher->addListener('foo.action', array($listener, 'onFooAction'));

$subscriber = new MySubscriber();
$dispatcher->addSubscriber($subscriber);

$dispatcher->addListener('baz.action', array($listener, 'onFooAction'));
$dispatcher->addListener('foo.action', function() {
    echo __FUNCTION__;
    echo "<br>";
});


echo "<h2>START</h2>";

echo "<h4>FOO-ACTION</h4>";
$dispatcher->dispatch('foo.action');

echo "<h4>BAR-ACTION</h4>";
$dispatcher->dispatch('bar.action');

echo "<h4>BAZ-ACTION</h4>";
$dispatcher->dispatch('baz.action');

echo "<h2>END</h2>";