4 releases
0.2.2 | Dec 22, 2020 |
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0.2.1 | Dec 22, 2020 |
0.2.0 |
|
0.1.1 | Nov 15, 2020 |
0.1.0 | Oct 24, 2020 |
#169 in Rust patterns
71 downloads per month
Used in mediasoup
13KB
170 lines
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};
fn main() {
let bag = Bag::default();
let handler_id = bag.add(move || {
println!("Hello")
});
bag.call_simple();
}
Close to real-world usage example:
use event_listener_primitives::{Bag, HandlerId};
fn main() {
let bag = Bag::default();
let handler_id = bag.add(Box::new(move || {
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 {
bar: Bag<Box<dyn Fn() + Send + Sync + 'static>>,
closed: BagOnce<Box<dyn FnOnce() + Send + Sync + 'static>>,
}
struct Inner {
handlers: Arc<Handlers>,
}
impl Drop for Inner {
fn drop(&mut self) {
self.handlers.closed.call_simple();
}
}
#[derive(Clone)]
pub struct Foo {
inner: Arc<Inner>,
}
impl Foo {
pub fn new() -> Self {
let handlers = Arc::<Handlers>::default();
let inner = Arc::new(Inner { handlers });
Self { inner }
}
pub fn do_bar(&self) {
// Do things...
self.inner.handlers.bar.call_simple();
}
pub fn do_other_bar(&self) {
// Do things...
self.inner.handlers.bar.call(|callback| {
callback();
});
}
pub fn on_bar<F: Fn() + Send + Sync + 'static>(&self, callback: F) -> HandlerId {
self.inner.handlers.bar.add(Box::new(callback))
}
pub fn on_closed<F: FnOnce() + Send + Sync + 'static>(&self, callback: F) -> HandlerId {
self.inner.handlers.closed.add(Box::new(callback))
}
}
fn main() {
let foo = Foo::new();
let on_bar_handler_id = foo.on_bar(|| {
println!("On bar");
});
foo
.on_closed(|| {
println!("On closed");
})
.detach();
// This will trigger "bar" callback just fine since its handler ID is not dropped yet
foo.do_bar();
drop(on_bar_handler_id);
// This will not trigger "bar" callback since its handler ID was already dropped
foo.do_other_bar();
// This will trigger "closed" callback though since we've detached handler ID
drop(foo);
println!("Done");
}
The output will be:
On bar
On closed
Done
Contribution
Feel free to create issues and send pull requests, they are highly appreciated!
License
Zero-Clause BSD
Dependencies
~800KB
~20K SLoC