Filters

a.rs

fn main() {
    let mut notifier = Notifier::new();
    notifier.add_filter(|n| n.incr_count(1));
    notifier.add_filter(|n| n.incr_count(1));
    
    let mut notice = Notice::new();
    
    println!("Before: {:#?}", notice);
    notifier.notify(&mut notice);
    println!("After:  {:#?}", notice);
}

#[derive(Debug)]
struct Notice {
    count: i32,
}


impl Notice {
    pub fn new() -> Self {
        Self {
            count: 0,
        }
    }
    
    pub fn incr_count(&mut self, count: i32) {
        self.count += count;
    }
}

struct Notifier<'a> {
    filters: Vec<Box<Fn(&mut Notice) + 'a>>
}

impl<'a> Notifier<'a> {
    pub fn new() -> Self {
        Self {
            filters: Vec::new(),
        }
    }
    
    pub fn add_filter<T: Fn(&mut Notice) + 'a>(&mut self, filter: T) {
        self.filters.push(Box::new(filter));
    }
    
    pub fn notify(&self, notice: &mut Notice) {
        for filter in &self.filters {
            filter(notice);
        }
    }
}