MaybeRc

This library provides a method of creating circular reference counted dependencies when creation of the nested objects can fail (return Result).

Details

Usually Rc::new_cyclic can be used:

fn new() -> Rc<Self> {
    Rc::new_cyclic(|weak| {
        let child = Child::new(weak);
        Self {
            child,
        }
    })
}

But what to do in cases when Child::new returns an Option or Result? This is the problem that maybe-rc tries to solve:

fn new() -> Result<Rc<Self>, ()> {
    try_new_cyclic_rc(|weak| {
        let child = Child::new(weak.clone())?;
        Ok(Self {
            child,
        })
    })
}

Original Idea

Original idea was much more powerful and could also handle async functions but was considered way too unsafe and breaking some contracts provided by Rc/Arc. There is a hope that it will be possible to implement properly in the future as a library or even inside std.

Its description can be found at README.md.contested.