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Home Page: https://www.youtube.com/TimurShemsedinov
License: MIT License
Simple EventEmitter with multiple listeners
Home Page: https://www.youtube.com/TimurShemsedinov
License: MIT License
I wrote this based on this, but did not get how the pub fn on<F>(&mut self, event: T, handler: F)
is working, and how it got fired by calling handler(&payload)
in the emit
can you explain little bit pls. thanks
use std::collections::HashMap;
use std::cmp::Eq;
use std::hash::Hash;
#[derive(Debug, Copy, Clone, Hash, Eq, PartialEq)]
enum GreetEvent {
SayHello,
SayBye,
}
type HandlerPtr<T> = Box<dyn Fn(&T)>; // Vec<Arc<dyn EventListener>>; //
pub struct EventEmitter<T: Hash + Eq, U> {
handlers: HashMap<T, Vec<HandlerPtr<U>>>,
}
impl<T: Hash + Eq, U> EventEmitter<T, U> {
/// Creates a new instance of `EventEmitter`.
pub fn new() -> Self {
Self {
handlers: HashMap::new(),
}
}
/// Registers function `handler` as a listener for `event`. There may be
/// multiple listeners for a single event.
pub fn on<F>(&mut self, event: T, handler: F)
where
F: Fn(&U) + 'static,
{
let event_handlers =
self.handlers.entry(event).or_insert_with(|| vec![]);
event_handlers.push(Box::new(handler));
}
/// Invokes all listeners of `event`, passing a reference to `payload` as an
/// argument to each of them.
pub fn emit(&self, event: T, payload: U) {
if let Some(handlers) = self.handlers.get(&event) {
for handler in handlers {
handler(&payload);
}
}
}
}
fn main() {
let mut emitter = EventEmitter::new();
emitter.on(GreetEvent::SayHello, |name| {
println!("Hello, {}!", name);
});
emitter.on(GreetEvent::SayHello, |name| {
println!("Someone said hello to {}.", name);
});
emitter.on(GreetEvent::SayBye, |name| {
println!("Bye, {}, hope to see you again!", name);
});
emitter.emit(GreetEvent::SayHello, "Alex");
emitter.emit(GreetEvent::SayBye, "Alex");
}
Для реализации из https://github.com/HowProgrammingWorks/EventEmitter/blob/master/JavaScript/a-prod.js при помощи строенной библиотеки https://nodejs.org/api/assert.html
Для примера
https://github.com/HowProgrammingWorks/EventEmitter/blob/master/JavaScript/1-simple.js
let ee = new EventEmitter();
let fn = function(data) {
console.dir(data);
};
ee.on('smth', fn);
Для @YARTI:
ee.get('smth'); // получить массив обработчиков по имени события
ee.remove('smth', fn); // удалить обработчик события
ee.shuffle('smth'); // перемешать обработчики
Для @GeorgeUA
ee.has('smth'); // есть ли хоть один обработчик
ee.clear('smth'); // очистить все обработчики
ee.onBefore('smth', fn); // вставить событие до уже имеющихся
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