Struct std::cell::RefMut1.0.0[][src]

pub struct RefMut<'b, T> where
    T: 'b + ?Sized
{ /* 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
[src]

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

The 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 used through Deref.

Examples

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'));Run

🔬 This is a nightly-only experimental API. (refcell_map_split #51476)

Split a RefMut into multiple RefMuts for different components of the borrowed data.

The underlying RefCell will remain mutably borrowed until both returned RefMuts go out of scope.

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

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

Examples

#![feature(refcell_map_split)]
use std::cell::{RefCell, RefMut};

let cell = RefCell::new([1, 2, 3, 4]);
let borrow = cell.borrow_mut();
let (mut begin, mut end) = RefMut::map_split(borrow, |slice| slice.split_at_mut(2));
assert_eq!(*begin, [1, 2]);
assert_eq!(*end, [3, 4]);
begin.copy_from_slice(&[4, 3]);
end.copy_from_slice(&[2, 1]);Run

Trait Implementations

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

Formats the value using the given formatter. Read more

impl<'b, T, U> CoerceUnsized<RefMut<'b, U>> for RefMut<'b, T> where
    T: Unsize<U> + ?Sized,
    U: ?Sized
[src]

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

Important traits for &'a mut I

Mutably dereferences the value.

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

The resulting type after dereferencing.

Important traits for &'a mut I

Dereferences the value.

impl<'a, T> Display for RefMut<'a, T> where
    T: Display + ?Sized
1.20.0
[src]

Formats the value using the given formatter. Read more

Auto Trait Implementations

impl<'b, T> !Send for RefMut<'b, T>

impl<'b, T> !Sync for RefMut<'b, T>