Simple Event Library

Contributing

• This is an open-source library, and contributions are welcome.
• If you have any suggestions, bug reports, or feature requests, please open an issue or submit a pull request on the project repository.

Requirement

• PHP version 8.2 or newer is required

Installation & Setup

• You can download using composer.
• If you don't have composer, install composer first.
• create file composer.json at your project root directory.
• Add this to composer.json

{
  "require": {
    "naingaunglwin-dev/event": "^1.0"
  }
}

• Run the following command in your terminal from the project's root directory:

composer install

If you already have composer.json file in your project, just run this command in your terminal,

composer require naingaunglwin-dev/event

Usage

<?php

require_once "vendor/autoload.php";

use NAL\Event\Event;

$event = new Event();

// Define the event
$event->on("message", function () {
    echo "Message Sent!";
});

// emit the event
$event->emit("message"); // Message Sent!

• Define event listeners with arguments

// Define the event with arguments
$event->on("message", function ($at) {
    echo "Sent message at $at";
});

// emit the event with arguments
$event->emit("message", date('Y-m-d H:i:s'));

• Define event listeners with Class arguments

$event->on("message", function (User $user) {
    echo $user->notify("message is sent");
});

$event->emit("message"); // You don't have to pass the argument if arguments are classes

• Define event listeners with priority

$event->on("message", function () {
    echo "Message Sent!";
}, 1);

$event->on("message", function () {
    $notify->user();
}, 2);

$event->emit("message"); // The higher priority listeners (lower numerical values) will be executed first.

• Define the event listeners just one time

$event->once("message", function () {
    echo "Message is sent";
});

$event->emit("message"); // "Message is sent"
$event->emit("message"); // "" (Empty string)

• Get the event listeners

// Get all listeners for a specific event
$listeners = $event->getListeners("message");

// Get all listeners for all events
$allListeners = $event->getListeners();

• Remove a Specific Listener

$listener = function () {
    echo "This message will be removed.";
};

// Add the listener
$event->on("message", $listener);

// Remove the specific listener
$event->removeListener("message", $listener);

// Try emitting the event
$event->emit("message"); // No output since the listener has been removed

• Remove All Listeners for a Specific Event

// Add multiple listeners to the event
$event->on("message", function () {
    echo "First listener";
});

$event->on("message", function () {
    echo "Second listener";
});

// Remove all listeners for the event
$event->removeListeners("message");

// Try emitting the event
$event->emit("message"); // No output since all listeners have been removed

• Remove All Listeners for All Events

// Add listeners to different events
$event->on("message", function () {
    echo "Message listener";
});

$event->on("notification", function () {
    echo "Notification listener";
});

// Remove all listeners for all events
$event->removeListeners();

// Try emitting the events
$event->emit("message"); // No output since all listeners have been removed
$event->emit("notification"); // No output since all listeners have been removed

Available since version v1.0.1 and above

• Defer the event to emit later

$event->on("message", function () {
    echo "The first message.\n";
});

$event->on("message", function () {
    echo "The second message.\n";
});

if ($shouldMessage) {
    $event->defer("message");
} else {
    // Other processes
}

// Other processes

// Dispatch all deferred events
$event->dispatch4deferred(); // If condition meet,
                             // "The first message."
                             // "The second message."

• Add Subscriber to event

// Subscriber class must implement to `\NAL\Event\EventSubscriber`

class Conversation implements \NAL\Event\EventSubscriber {

    /**
    * @inheritDoc
    */
    public function getEvents(): array
    {
        return [
            "morning"   => "greeting",
            "afternoon" => "greeting",
            "goodbye"   => ["goodbye", "end"]
        ];
    }

    public function greeting($time, $name)
    {
        echo "Good $time, $name!\n";
    }
    
    public function goodbye($name)
    {
        echo "Goodbye, $name!\n";
    }
    
    public function end()
    {
        echo "Have a nice day!\n";
    }
}

$event = new \NAL\Event\Event();

$event->subscribe(new Conversation());

$event->emit("morning", "Morning","David"); // "Good Morning, David!"

$event->emit("afternoon", "Afternoon", "John"); // "Good Afternoon, John!"

$event->emit("goodbye", "Alex"); // "Goodbye, Alex!"
                                 // "Have a nice day!"

// You can also unsubscribe the subscribed listener
$event->unsubscribe(new Conversation());