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maxkaemmerer/events
===================

Provides Interfaces and Implementations for Event, EventSubscriber communication

v1.0.0(7y ago)0261MITPHPPHP >=7.2

Since Jul 21Pushed 7y agoCompare

[ Source](https://github.com/maxkaemmerer/events)[ Packagist](https://packagist.org/packages/maxkaemmerer/events)[ RSS](/packages/maxkaemmerer-events/feed)WikiDiscussions master Synced 3d ago

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maxkaemmerer/events
===================

[](#maxkaemmererevents)

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Description:
------------

[](#description)

This library offers interfaces and implementations for a simple event, event-subscriber, event-courier structure.

This is of course not an original idea, but my preferred and fairly simple implementation.

The code is fully tested, I however do not take responsibility for use in production.

Use at your own risk.

Installation:
-------------

[](#installation)

`composer require maxkaemmerer/events`

Usage:
------

[](#usage)

Generally you don't want to subscribe each `EventSubscriber` by hand. You might want to use dependency injection via a container or service-manager.

(An example for the Symfony Framework would be using a `CompilerPass`)

You would also want to inject the `EventCourier` itself via dependency injection wherever you need it.

Feel free to create your own implementations of `EventCourier`, `Subscription` and `Payload` if you require something more advanced.

#### Subscribe an EventSubscriber:

[](#subscribe-an-eventsubscriber)

Subscribe an `EventSubscriber` to the `EventCourier`. The `EventSubscriber`'s `subscription()` method returns a `Subscription`, which contains the name of the `Event` that the `EventSubscriber` subscribes to and the priority at which it wants to be notified.

(The higher the priority, the earlier the `EventSubscriber` get notified of the `Event`, assuming there are other `EventSubscriber`s with lower priority.)

Best practice would be using the fully qualified class name of the event. `MyEvent::class`

The `EventSubscriber::on($event)` method is where your actual domain logic happens.

Feel free to inject services, a container, or whatever else you need, into your `EventSubscriber`s.

```
$courier = new SimpleEventCourier();

$courier->subscribe(new class implements EventSubscriber
{

    /**
     * @param Event $event
     */
    public function on(Event $event): void
    {
        echo 'Notify Shipping!'  . PHP_EOL;
    }

    /**
     * @return EventSubscription
     */
    public function subscription(): EventSubscription
    {
        return Subscription::fromEventNameAndPriority('PaymentReceived', 50);
    }
});

```

#### Dispatch an Event:

[](#dispatch-an-event)

Dispatching an `Event` causes the `EventCourier` to notify all `EventSubscriber`s, who's `Subscription::event()` method matches the `Event`'s name, specified by `Event:name()`, and calls their `EventSubscriber::on($event)` method in order of priority.

IMPORTANT: `EventSubscriber`'s and the `EventCourier` never return anything.

```
...

// The EventSubscriber was subscribed

echo 'Payment received.'  . PHP_EOL;
$courier->dispatch(new class implements Event
{
    public function payload(): EventPayload
    {
        // the payload should of course be built or set in the constructor
        return Payload::fromArray(['price' => '99.99€', 'method' => 'creditCard', 'timestamp' => '12345678']);
    }

    public function name(): string
    {
        // best practice would be using the fully qualified class name MyEvent::class
        return 'PaymentReceived';
    }
});

```

Result:

```
Payment received.
Notify Shipping!

```

#### Full Example:

[](#full-example)

```