gistfile1.rs

pub struct Destructed<'a, T> {
    fun: Box<for <'b> FnOnce<(&'b T,), ()> + 'a>,
    active: bool,
    val: T
}

impl<'a, T> Destructed<'a, T> {
    pub fn new(val: T, f: Box<for <'b> FnOnce<(&'b T,), ()> + 'a>) -> Destructed<'a, T> {
        Destructed { val: val, fun: f, active: true }
    }

    pub fn inner(&'a self) -> &'a T {
        &self.val
    }

    pub fn release(&mut self) {
        self.active = false;
    }
}

#[unsafe_destructor]
impl<'a, T> Drop for Destructed<'a, T> {
    fn drop(&mut self) {
        if self.active {
            (*self.fun).call_once((&self.val,));
        }
    }
}