Shared via Rust Playground

playground.rs

struct Manager {
    callbacks: Vec<Box<FnMut()>>,
}

impl Manager {
    fn new() -> Manager {
        Manager { callbacks: Vec::new() }
    }

    fn register(&mut self, callback: Box<FnMut()>) {
        self.callbacks.push(callback);
    }

    fn call(&mut self) {
        for callback in &mut self.callbacks {
            callback();
        }
    }
}

struct Plugin {
    counter: u32,
}

impl Plugin {
    fn new() -> Plugin {
        Plugin { counter: 0 }
    }

    fn increment(&mut self) {
        println!("Increment");
        self.counter += 1;
    }

    fn get(&self) -> u32 {
        self.counter
    }
}

fn main() {
    use std::rc::Rc;
    use std::cell::RefCell;

    let mut manager = Manager::new();

    manager.register(Box::new(|| {
        println!("Hello!");
    }));
    manager.register(Box::new(|| {
        println!("Hola!");
    }));

    let plugin = Rc::new(RefCell::new(Plugin::new()));

    let rc = plugin.clone();
    manager.register(Box::new(move || {
        rc.borrow_mut().increment();
    }));
    let rc = plugin.clone();
    manager.register(Box::new(move || println!("Plugin: {}", rc.borrow().get())));

    manager.call();
    manager.call();
    manager.call();
    manager.call();
    manager.call();
}