use std::cell::Cell;
use std::rc::Rc;

struct Stat {
    name: String,
    cur_mean: f64,
    cur_variance: f64,
    covs: Vec<StatCov>,
}

impl Stat {
    fn update(&mut self, time: f64, val: f64) {
        for cov in &self.covs {
            cov.update(time, val);
        }
    }
}

#[derive(Clone)]
struct StatCov {
    inner: Rc<InnerStatCov>,
}

impl StatCov {
    fn update(&self, time: f64, val: f64) {
        self.inner.update(time, val);
    }
}

#[derive(Default)]
struct InnerStatCov {
    cur_mean: Cell<f64>,
    cur_variance: Cell<f64>,
}

impl InnerStatCov {
    fn update(&self, time: f64, val: f64) {}
}

fn main() {
    let shared_cov = StatCov {
        inner: Rc::new(InnerStatCov::default()),
    };
    let stat1 = Stat {
        name: "stat1".into(),
        cur_mean: 0.0,
        cur_variance: 0.0,
        covs: vec![shared_cov.clone()],
    };

    let stat2 = Stat {
        name: "stat2".into(),
        cur_mean: 0.0,
        cur_variance: 0.0,
        covs: vec![shared_cov],
    };
}