Awesome

NotificationSystem is a lightweight signals framework for GameMaker Studio 2.3+. It's extremly simple to setup and easy to use.

You only need the 'NotificationSystem' script, but this whole repository contains a demo project showcasing a simple implementation.

Changelog

v1.2.6

• Fixed Feather errors, warnings and suggestions.

v1.2.5

• Fixed indentation errors in NotificationSystem script
• Fixed some minor JSDoc warnings

v1.2.4

• Suppressed tedious warnings
• Added a setting to disable automatic subscription to global channel when omitting it from subscribe([...])
• Fixed a bug where unsubscribe() wasn't working
• Fixed a bug where log_channels() could crash if a channel contained a broken reference id

v1.2.3

• Instances can now decide if they want to listen to the global channel or just listening for messages in their own specific channels they subscribe to. To subscribe to the global channel you can either leave subscribe() blank or use subscribe(global)
• The global keyword can also be used in an array, for example subscribe([global, "channel_1"])
• Added alias on() for add()
• Many thanks to @FaultyFunctions for these changes

v1.2.2

• Added function log_channels()
• Added function channel_exists(name)

v1.2.1

• Added support for subscribing to multiple channels at once, example below
• Fixed bug when calling subscribe("channel") could crash

receiver = new Receiver(["controllers", "effects", "channel5"]);
// or
subscribe(["controllers", "effects", "channel5"]);

Installation

• Copy the NotificationSystem script into your project.

Usage

• In the Create event of an object, create a variable holding a new instance of Receiver. This object is now ready to receive messages over the notification bus.

• In order to react to messages sent over the bus you bind callbacks to messages with the function add(). The messages can be of any type, such as enums, numbers, strings etc.

// Initializing the listener
receiver = new Receiver();

receiver.add("Monster killed", function(amount) {
    increase_score(amount);
});

receiver.add(MESSAGES.death, function() {
    game_restart();
});

receiver.add(3, function() {
    show_debug_message("Message 3 received!");
});

• It is also possible to subscribe to specific channels

// Subscribe to channel "enemies"
subscribe("enemies");

// Subscribe instance 100010 to channel "enemies"
subscribe(100010, "enemies");

• You can also bind an empty callback to a message in order to only react to messages which includes a callback.

receiver.add("hello");

• Any object can broadcast a message on the notification bus, this is performed with the function broadcast(). Messages broadcasted can contain a callback, which will trigger after the callback bound on the receiver end. It is also possible to send an argument with the message, which the callback bound on the receiver end will receive.

broadcast(MESSAGES.death);

broadcast("Monster killed", 10);

broadcast("hello", function() {
    show_debug_message("hello, world!");
});

broadcast_channel("hello", "enemies");

• Don't forget to unsubscribe to the notification bus when deleting an object that is subscribed. This is performed by simply calling the function unsubscribe(), preferably in the cleanup event of the object.

// Don't waste time trying to send me any new messages. I'm not home!
unsubscribe();

Documentation

Check out the wiki for further documentation.