src/test/run-pass/resource-destruct.rs

// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
// file at the top-level directory of this distribution and at
// http://rust-lang.org/COPYRIGHT.
//
// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
// option. This file may not be copied, modified, or distributed
// except according to those terms.

#![feature(managed_boxes, unsafe_destructor)]

use std::cell::Cell;
use std::gc::{GC, Gc};

struct shrinky_pointer {
  i: Gc<Gc<Cell<int>>>,
}

#[unsafe_destructor]
impl Drop for shrinky_pointer {
    fn drop(&mut self) {
        println!("Hello!"); self.i.set(self.i.get() - 1);
    }
}

impl shrinky_pointer {
    pub fn look_at(&self) -> int { return self.i.get(); }
}

fn shrinky_pointer(i: Gc<Gc<Cell<int>>>) -> shrinky_pointer {
    shrinky_pointer {
        i: i
    }
}

pub fn main() {
    let my_total = box(GC) box(GC) Cell::new(10);
    { let pt = shrinky_pointer(my_total); assert!((pt.look_at() == 10)); }
    println!("my_total = {}", my_total.get());
    assert_eq!(my_total.get(), 9);
}