💠 Rust Cells §

= a type to perform (non-thread-safe) interior mutability, part of std::cell

Types §

Cell<T> §

= a struct containing a private value of Type T, which can be get/set, even without ownership

• Cell::new(val) → new Cell, moving val into it
• cell.get() → returns copy of val
• cell.set(new_val) → stores new_val in cell
  • doesn’t take &mut as parameter

Requirements §

• T implements the copy trait

RefCell<T> §

= like Cell T, but supports borrowing references to val of T

• RefCell::new(val) → new RefCell, move val into it
• ref_cell.borrow()
  • → returns Ref<T> (= shared reference to val in ref_cell)
  • panic if val is mutably borrowed
• ref_cell.borrow_mut()
  • → returns RefMut<T> (mut reference to val in ref_cell)
  • panic if val is already borrowed
• ref_cell.try_borrow(), ref_cell.try_borrwo_mut()
  • → like borrow(), borrow_mut(), but returns Result