shcarp/rs-event-emitter

Event System

A simple rs-event-emitter implementation in Rust.

The rs-event-emitter allows you to register event handlers for specific events and emit events with associated data. It provides a way to decouple components and enable communication through events.

Currently, the parameters only support types that have implemented cloning. Improvements will be made in the future.

Usage

To use the event system, follow these steps:

1. Add the following to your Cargo.toml file:

[dependencies]
rs-event-emitter = "0.0.5"

2. Import the crate in your main.rs or lib.rs file:

extern crate rs_event_emitter::*;

3. Create an event handler function:

// Define the event handlers
let handler = EventHandler::new(Box::new(move |val: i32| {
    println!("Handler called with value: {}", val);
    let mut data = data_clone.lock().unwrap();
    data.called = true;
    data.value = val;
}));

// if you have more parameters, you can use a tuple
let handler = EventHandler::new(Box::new(move |(a, b, c): (i32, &str, f64)| {
    println!("event1: {}, {}, {}", a, b, c);
    assert_eq!(a, 42);
    assert_eq!(b, "hello");
    assert_eq!(c, 3.14);
}));

4. Register the event handler for a specific event:

let emitter = EventEmitter::new();

// Register the event handlers
emitter.on("test_event", &handler);

5. Emit an event:

emitter.emit("test_event", Box::new(24));

6. Unregister event handlers using the EventEmitter::off method:

emitter.off("test_event", &handler);

API

EventEmitter

• fn new() -> Self: Creates a new EventEmitter instance.

• fn on(&self, event: &'static str, handler: Arc<dyn Handle>): listen an event handler for a specific event.

• fn off(&self, event: &str, handler: Arc<dyn Handle>): unListen an event handler for a specific event.

• fn emit(&self, event: &str, data: Box<dyn Any>): Emits an event with associated data, triggering the registered event handlers for that event.

EventHandler

• fn new(handler: fn(T)) -> Self: Creates a new event handler with the provided closure.

Examples

use rs_event_emitter::*;

fn main() {
    let data = Arc::new(Mutex::new(TestData {
        called: false,
        value: 0,
    }));
    let data_clone = data.clone();

    let handler = EventHandler::new(Box::new(move |val: i32| {
        println!("Handler called with value: {}", val);
        let mut data = data_clone.lock().unwrap();
        data.called = true;
        data.value = val;
    }));

    let emitter = EventEmitter::new();

    // Register the event handler
    emitter.on("test_event", &handler);

    let clone_emitter = emitter.clone();

    let t_handler = thread::spawn(move || {
        thread::sleep(std::time::Duration::from_millis(100));
        clone_emitter.emit("test_event", Box::new(42));
    });

    t_handler.join().unwrap();

    {
        let data = data.lock().unwrap();

        println!("{:?}", data.called);
        // Check if the handler was called and the value was set correctly
        assert!(data.called);
        assert_eq!(data.value, 42);
    }

    // Remove the event handler
    emitter.off("test_event", &handler);

    // Reset the test data
    {
        let mut data = data.lock().unwrap();
        data.called = false;
        data.value = 0;
    }

    // Emit the event again
    emitter.emit("test_event", Box::new(24));

    // Verify the handler was not called after being removed
    let data = data.lock().unwrap();
    assert!(!data.called);
    assert_eq!(data.value, 0);
}

When you run the above code, you should see the event handlers being called for the emitted events.

Contributing

If you would like to contribute to this project, please open an issue or submit a pull request.

License

This project is licensed under the MIT License