How to use Symfony’s Event Dispatcher component?

To use Symfony's Event Dispatcher component, follow these steps:

Register event listeners or subscribers: You can register event listeners by creating a class that implements the EventSubscriberInterface interface or by registering callable functions as event listeners.
Define events: Define specific events that can be dispatched within your application. This can be done by creating event classes that extend the Symfony\Component\EventDispatcher\Event class.
Dispatch events: To dispatch an event, you can use the dispatch() method on the EventDispatcherInterface instance.

Here's an example of how to use Symfony's EventDispatcher component:

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

// Create an event class
class MyEvent extends Event
{
    const NAME = 'my.event.name';
}

// Create an event listener
$myEventListener = function (MyEvent $event) {
    // Handle the event
    echo 'Event dispatched: ' . $event->getName() . "\n";
};

// Register the event listener
$dispatcher = new EventDispatcher();
$dispatcher->addListener(MyEvent::NAME, $myEventListener);

// Dispatch the event
$event = new MyEvent();
$dispatcher->dispatch(MyEvent::NAME, $event);

This example demonstrates how to define an event class, register an event listener, and dispatch the event using the Symfony Event Dispatcher component.