use std::rc::Rc;
use std::cell::{RefCell, RefMut};
use std::collections::HashMap;

struct GE {
    env: std::collections::HashMap<String, Rc<RefCell<FnMut() -> i32>>>,
}

struct HasDrop { i: i32 }

impl Drop for HasDrop {
    fn drop(&mut self) {
        println!("Dropping!");
    }
}

impl GE {
    fn add<T>(&mut self, funcname: &str, func: T) where T: 'static + FnMut() -> i32 {
         self.env.insert(String::from(funcname), Rc::new(RefCell::new(func)));
    }
    fn call(&mut self, funcname: &str) -> i32 {
        //let mut ret = 0;
        let f = Rc::get_mut(self.env.get_mut(funcname).unwrap()).unwrap().get_mut();
            //|fx| { ret = fx(); fx });
        //ret
        f()
    }
}

fn o() {
    let mut g = GE { env: HashMap::new() };
    let fo = HasDrop { i: 20 };
    g.add("foo2", move || { fo.i });
    println!("i1: {}", g.call("foo2"));
    println!("i2: {}", g.call("foo2"));
}

fn main() {
    println!("A");
    o();
    println!("B");
    o();
    println!("C");
    o();
    println!("D");
}