Ferris Gc example

ferris-gc-local-gc-ex0.rs

use ferris_gc::{Gc, GcRefCell, Trace, Finalize, ferris_gc_main, ApplicationCleanup};
use std::{time, thread};
use std::fs::File;
use std::io::Write;

#[derive(Trace)]
struct MyStruct {
    id: u32,
}

impl Finalize for MyStruct {
    fn finalize(&self) {
        println!("MyStruct in finalize !!");
        let mut file = File::create("foo.txt");
        match file {
            Ok(mut f) => { f.write_all(b"Hello, world!") },
            Err(e) => { Err(e) },
        };
    }
}

#[derive(Trace, Finalize)]
struct Counter {
    count: Gc<u32>,
}

#[ferris_gc_main]
fn main() {
    {
        let counter = Gc::new(2);
        let gc0 = Gc::new(MyStruct { id: 3 });
        let gc1 = GcRefCell::new(MyStruct { id: 4 });
        gc1.borrow_mut().id = 5;
        let gc3 = Gc::new(Counter { count: counter.clone() });
    }
    let ten_secs = time::Duration::from_secs(5);
    thread::sleep(ten_secs);
    println!("Hello, GC World !!");
}