Struct std::cell::Ref

pub struct Ref<'b, T> where T: 'b + ?Sized { /* fields omitted */ }

Wraps a borrowed reference to a value in a RefCell box. A wrapper type for an immutably borrowed value from a RefCell<T>.

See the module-level documentation for more.

Methods

impl<'b, T> Ref<'b, T> where T: ?Sized

fn clone(orig: &Ref<'b, T>) -> Ref<'b, T>

Copies a Ref.

The RefCell is already immutably borrowed, so this cannot fail.

This is an associated function that needs to be used as Ref::clone(...). A Clone implementation or a method would interfere with the widespread use of r.borrow().clone() to clone the contents of a RefCell.

fn map<U, F>(orig: Ref<'b, T>, f: F) -> Ref<'b, U> where F: FnOnce(&T) -> &U, U: ?Sized

Make a new Ref for a component of the borrowed data.

The RefCell is already immutably borrowed, so this cannot fail.

This is an associated function that needs to be used as Ref::map(...). A method would interfere with methods of the same name on the contents of a RefCell used through Deref.

Example

use std::cell::{RefCell, Ref};

let c = RefCell::new((5, 'b'));
let b1: Ref<(u32, char)> = c.borrow();
let b2: Ref<u32> = Ref::map(b1, |t| &t.0);
assert_eq!(*b2, 5)

Trait Implementations

impl<'b, T> Deref for Ref<'b, T> where T: ?Sized

type Target = T

The resulting type after dereferencing

fn deref(&self) -> &T

The method called to dereference a value

impl<'b, T, U> CoerceUnsized<Ref<'b, U>> for Ref<'b, T> where T: Unsize<U> + ?Sized,
        U: ?Sized

impl<'b, T> Debug for Ref<'b, T> where T: Debug + ?Sized

fn fmt(&self, f: &mut Formatter) -> Result<(), Error>

Formats the value using the given formatter.