Struct std::cell::RefMut [] [src]

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

A wrapper type for a mutably borrowed value from a RefCell<T>.

See the module-level documentation for more.

Methods

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

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

Unstable

: recently added

Make a new RefMut`RefMut` for a component of the borrowed data, e.g. an enum variant.

The RefCell`RefCell` is already mutably borrowed, so this cannot fail.

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

Example

#![feature(cell_extras)] fn main() { use std::cell::{RefCell, RefMut}; let c = RefCell::new((5, 'b')); { let b1: RefMut<(u32, char)> = c.borrow_mut(); let mut b2: RefMut<u32> = RefMut::map(b1, |t| &mut t.0); assert_eq!(*b2, 5); *b2 = 42; } assert_eq!(*c.borrow(), (42, 'b')); }
use std::cell::{RefCell, RefMut};

let c = RefCell::new((5, 'b'));
{
    let b1: RefMut<(u32, char)> = c.borrow_mut();
    let mut b2: RefMut<u32> = RefMut::map(b1, |t| &mut t.0);
    assert_eq!(*b2, 5);
    *b2 = 42;
}
assert_eq!(*c.borrow(), (42, 'b'));

fn filter_map<U, F>(orig: RefMut<'b, T>, f: F) -> Option<RefMut<'b, U>> where U: ?Sized, F: FnOnce(&mut T) -> Option<&mut U>

Unstable

: recently added

Make a new RefMut`RefMut` for a optional component of the borrowed data, e.g. an enum variant.

The RefCell`RefCell` is already mutably borrowed, so this cannot fail.

This is an associated function that needs to be used as RefMut::filter_map(...). A method would interfere with methods of the same name on the contents of a RefCell`RefCellused throughDeref`.

Example

#![feature(cell_extras)] fn main() { use std::cell::{RefCell, RefMut}; let c = RefCell::new(Ok(5)); { let b1: RefMut<Result<u32, ()>> = c.borrow_mut(); let mut b2: RefMut<u32> = RefMut::filter_map(b1, |o| { o.as_mut().ok() }).unwrap(); assert_eq!(*b2, 5); *b2 = 42; } assert_eq!(*c.borrow(), Ok(42)); }
use std::cell::{RefCell, RefMut};

let c = RefCell::new(Ok(5));
{
    let b1: RefMut<Result<u32, ()>> = c.borrow_mut();
    let mut b2: RefMut<u32> = RefMut::filter_map(b1, |o| {
        o.as_mut().ok()
    }).unwrap();
    assert_eq!(*b2, 5);
    *b2 = 42;
}
assert_eq!(*c.borrow(), Ok(42));

Trait Implementations

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

type Target = T

fn deref(&'a self) -> &'a T

impl<'b, T> DerefMut for RefMut<'b, T> where T: ?Sized

fn deref_mut(&'a mut self) -> &'a mut T

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

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