https://github.com/nazar-pc/event-listener-primitives

Low-level primitive for building Node.js-like event listeners
https://github.com/nazar-pc/event-listener-primitives

emitter event listener

Last synced: about 1 month ago
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Low-level primitive for building Node.js-like event listeners

• Host: GitHub
• URL: https://github.com/nazar-pc/event-listener-primitives
• Owner: nazar-pc
• License: 0bsd
• Created: 2020-10-24T17:28:39.000Z (about 4 years ago)
• Default Branch: master
• Last Pushed: 2021-09-02T23:46:00.000Z (about 3 years ago)
• Last Synced: 2024-10-14T14:39:48.120Z (about 1 month ago)
• Topics: emitter, event, listener
• Language: Rust
• Homepage:
• Size: 34.2 KB
• Stars: 4
• Watchers: 3
• Forks: 2
• Open Issues: 0
• Metadata Files:
  • Readme: readme.md
  • Changelog: changelog.md
  • License: copying.md

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README

        
## Event listener primitives

[![Build Status](https://img.shields.io/travis/com/nazar-pc/event-listener-primitives/master?style=flat-square)](https://travis-ci.com/nazar-pc/event-listener-primitives)

[![Crates.io](https://img.shields.io/crates/v/event-listener-primitives?style=flat-square)](https://crates.io/crates/event-listener-primitives)

[![Docs](https://img.shields.io/badge/docs-latest-blue.svg?style=flat-square)](https://docs.rs/event-listener-primitives)

[![License](https://img.shields.io/github/license/nazar-pc/event-listener-primitives?style=flat-square)](https://github.com/nazar-pc/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:

```rust

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:

```rust

use event_listener_primitives::{Bag, BagOnce, HandlerId};

use std::sync::Arc;

#[derive(Default)]

struct Handlers {

    action: Bag>,

    closed: BagOnce>,

}

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(&self, callback: F) -> HandlerId {

        self.handlers.action.add(Arc::new(callback))

    }

    pub fn on_closed(&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:

```text

On action

On closed

Done

```

## Contribution

Feel free to create issues and send pull requests, they are highly appreciated!

## License

Zero-Clause BSD