EventEmitter for Arduino

EventEmitter is a lightweight, memory‑efficient event emitter library for Arduino. It brings the familiar Node.js event model to embedded systems, allowing you to attach callbacks to events, emit events with custom arguments, and manage one‑time or recurring events—all without dynamic memory allocation!

How to install

The simplist way to install is searching "EventEmitter" in the Arduino IDE lib manager!

How to Manually Install

1. Download: EventEmitter.zip
2. In the Arduino IDE's menu bar click: Sketch > Include Library > Add .ZIP Library
3. Select "EventEmitter.zip"
4. Done!

How to Find Examples After Installing

In the Arduino IDE's menu bar click: File > Examples > EventEmitter > Choose an example

Features

• Event Registration: Attach multiple callbacks to an event.
• Event Emission: Emit events and pass arguments to callbacks.
• One‑Shot Listeners: Automatically remove listeners after their first call.
• Listener Management: Remove individual or all listeners.
• Memory Efficiency: Uses fixed‑size buffers and statically allocated arrays, ideal for microcontrollers.

Using EventEmitter

Below are simple snippet examples to help you get started.

Registering an Event Listener

Attach a callback that will be called whenever the event is triggered.

// Define a simple event handler.
void onMyEvent() {
  // Insert code to run when "myEvent" occurs.
}
// Register the "myEvent" event.
emitter.on("myEvent", onMyEvent);

Emitting an Event

Trigger the event, with or without arguments.

// Emit "myEvent" with no arguments.
emitter.emit("myEvent");
// Emit an event with arguments (for example, an integer and a float).
emitter.emit("dataEvent", 42, 3.14);

Using One-Shot Listeners

Register a listener that automatically removes itself after the first call.

// The lambda will be executed only once when "startup" is emitted.
emitter.once("startup", [](){
  // Code that runs just once.
});

Removing a Specific Listener

Remove a previously registered listener.

// Remove the onMyEvent callback from "myEvent".
emitter.removeListener("myEvent", onMyEvent);

Removing All Listeners

Clear all callbacks for a specific event or for all events.

// Remove all listeners from "myEvent".
emitter.removeAllListeners("myEvent");
// Remove every listener from all events.
emitter.removeAllListeners();

Adjusting Maximum Listeners

Limit or retrieve the maximum number of listeners that can be registered per event.

// Set the maximum number of listeners per event to 3.
emitter.setMaxListeners(3);
// Retrieve the current maximum listener count.
size_t maxListeners = emitter.getMaxListeners();

License

This project is licensed under the MIT License.