[aystatic]

> Runtime borrow checking: RefCell<T> and Rc<T>. Can give other examples, but admittedly they need `unsafe` blocks.

Where are the “subtle linguistic distinctions”? These types do two completely different things. And neither are even capable of being used in a multithreaded context due to `!Sync` (and `!Send` for Rc and refguards)

[lenkite]

I did say "runtime borrow checking" ie using them together. Example: `Rc::new(RefCell::new(value));`. This will panic at runtime. Maybe I should have used the phrase "dynamic borrowing" ?

https://play.rust-lang.org/?version=stable&mode=debug&editio...

You don't need different threads. I said concurrency not multi-threading. Interleaving tasks within the same thread (in an event loop for example) can cause panics.

[aystatic]

I understand what you meant (but note that allocating an Rc isn’t necessary; &RefCell would work just fine). I just didn’t see the “subtle linguistic distinctions” - and still don’t… maybe you could point them out for me?

https://doc.rust-lang.org/stable/std/cell/struct.RefCell.htm...

https://doc.rust-lang.org/stable/std/cell/struct.RefCell.htm...