Expand description
§Event listener primitives
This crate provides a low-level primitive for building Node.js-like event listeners.
The 3 primitives are Bag that is a container for Fn() event handlers, BagOnce the same for FnOnce() event handlers and HandlerId that will remove event handler from the bag on drop.
Trivial example:
use event_listener_primitives::{Bag, HandlerId};
use std::sync::Arc;
fn main() {
let bag = Bag::default();
let handler_id = bag.add(Arc::new(|| {
println!("Hello");
}));
bag.call_simple();
}Close to real-world usage example:
use event_listener_primitives::{Bag, BagOnce, HandlerId};
use std::sync::Arc;
#[derive(Default)]
struct Handlers {
action: Bag<Arc<dyn Fn() + Send + Sync + 'static>>,
closed: BagOnce<Box<dyn FnOnce() + Send + 'static>>,
}
pub struct Container {
handlers: Handlers,
}
impl Drop for Container {
fn drop(&mut self) {
self.handlers.closed.call_simple();
}
}
impl Container {
pub fn new() -> Self {
let handlers = Handlers::default();
Self { handlers }
}
pub fn do_action(&self) {
// Do things...
self.handlers.action.call_simple();
}
pub fn do_other_action(&self) {
// Do things...
self.handlers.action.call(|callback| {
callback();
});
}
pub fn on_action<F: Fn() + Send + Sync + 'static>(&self, callback: F) -> HandlerId {
self.handlers.action.add(Arc::new(callback))
}
pub fn on_closed<F: FnOnce() + Send + 'static>(&self, callback: F) -> HandlerId {
self.handlers.closed.add(Box::new(callback))
}
}
fn main() {
let container = Container::new();
let on_action_handler_id = container.on_action(|| {
println!("On action");
});
container
.on_closed(|| {
println!("On container closed");
})
.detach();
// This will trigger "action" callback just fine since its handler ID is not dropped yet
container.do_action();
drop(on_action_handler_id);
// This will not trigger "action" callback since its handler ID was already dropped
container.do_other_action();
// This will trigger "closed" callback though since we've detached handler ID
drop(container);
println!("Done");
}The output will be:
On action
On closed
Done§Contribution
Feel free to create issues and send pull requests, they are highly appreciated!
§License
Zero-Clause BSD