heybigname / event-dispatcher
Event Dispatcher with a focus on Domain Events
Requires
- php: >=5.4.0
- illuminate/container: ~4.2
Requires (Dev)
- henrikbjorn/phpspec-code-coverage: 1.0.*
- laravel/framework: ~4.2
- phpspec/phpspec: ~2.0
- satooshi/php-coveralls: ~0.6
This package is not auto-updated.
Last update: 2024-10-22 03:10:05 UTC
README
An Event Dispatcher built with a focus on Domain Events.
Table of Contents
Installation
Run the command below to install via Composer
composer require heybigname/event-dispatcher
Integrations
Although this package is completely framework agnostic, it does have integrations with framework(s). Currently only Laravel 4.x is included, but if requested others can be added.
Laravel
To install into a Laravel project, first do the composer install then add the following class to your config/app.php
service providers list.
'BigName\EventDispatcher\Integrations\Laravel\ServiceProvider',
That's all it takes for the Laravel integration. Now it's possible to inject or make a Dispatcher like this:
use BigName\EventDispatcher\Dispatcher; class RegisterMemberHandler implements Handler { private $dispatcher; public function __construct(Dispatcher $dispatcher) { $this->dispatcher = $dispatcher; } }
$dispatcher = App::make('BigName\EventDispatcher\Dispatcher');
How It Works
Event
In your domain you'll create an event, for let's say when a new member has been registered.
Lets call this event MemberWasRegistered
. This event will hold the necessary information for the listener to fulfill it's job.
You have complete freedom about which arguments it takes, since you'll be the one passing them in.
In some ways this event is a Data Transfer Object
(DTO).
For example:
<?php namespace Domain\Accounts\Events; use BigName\EventDispatcher\Event; class MemberWasRegistered implements Event { private $member; public function __construct($member) { $this->member = $member; } public function getMember() { return $this->member; } public function getName() { return 'MemberWasRegistered'; } }
Listener
An event without a listener does no good for us, so lets create an email listener WelcomeNewlyRegisteredMemberListener
for the event MemberWasRegistered
.
<?php namespace Domain\Accounts\EventListeners; use BigName\EventDispatcher\Listener; use BigName\EventDispatcher\Event; class WelcomeNewlyRegisteredMemberListener implements Listener { private $mailer public function __construct($mailer) { $this->mailer = $mailer; } public function handle(Event $event) { // Do something with the event } }
Same rule with the listeners as the events, you have complete freedom with the arguments.
When an event is dispatched the handle
method on the correct listeners will be called.
Listening
Now we got the building blocks ready lets start listening for some new members, shall we. For the sake of this example, the code is kept as simple as possible.
use BigName\EventDispatcher\Dispatcher; use Domain\Accounts\Events\MemberWasRegistered; use Domain\Accounts\EventListeners\WelcomeNewlyRegisteredMemberListener; // Listening for event $mailer = // Some mail package... $listener = new WelcomeNewlyRegisteredMemberListener($mailer); $dispatcher = new Dispatcher; $dispatcher->addListener('MemberWasRegistered', $listener); // Dispatching event $member = // A wild member appeared.. $event = new MemberWasRegistered($member); $dispatcher->dispatch($event);
Lazy Listening
It's possible to have your listeners lazy loaded. Merely pass a string with full namespace of the class. Currently this only works with the Laravel (Illuminate) Container. Other containers can be supported, if requested.
use Illuminate\Container\Container; use BigName\EventDispatcher\Dispatcher; use BigName\EventDispatcher\Containers\LaravelContainer; $container = new LaravelContainer(new Container); $dispatcher = new Dispatcher($container); $dispatcher->addLazyListener('MemberWasRegistered', 'Domain\Accounts\EventListeners\WelcomeNewlyRegisteredMemberListener');
This will construct and instantiate the listener(s) on dispatch()
or getLazyListeners()
.
Lazy loading listeners can help mitigate the overhead if you have all your listeners instantiated on bootstrap.
Dispatching Multiple Events
For extra hipster points you can dispatch multiple events in 1 call.
use BigName\EventDispatcher\Dispatcher; use Domain\Accounts\MemberWasRegistered; use Domain\Achievements\MemberEarnedAchievement; $member = ...; $achievement = ...; $events = [ new MemberWasRegistered($member), new MemberEarnedAchievement($member, $achievement) ]; $dispatcher = new Dispatcher; $dispatcher->dispatch($events);
Maintainers
This package is maintained by Mitchell van Wijngaarden of Big Name
License
This package is licensed under the MIT license.