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Struct std::cell::RefMut

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]

pub fn map<U, F>(orig: RefMut<'b, T>, f: F) -> RefMut<'b, U> where
    F: FnOnce(&mut T) -> &mut U,
    U: ?Sized, [src]1.8.0

Makes 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'));

pub fn map_split<U, V, F>(
    orig: RefMut<'b, T>,
    f: F
) -> (RefMut<'b, U>, RefMut<'b, V>) where
    F: FnOnce(&mut T) -> (&mut U, &mut V),
    U: ?Sized,
    V: ?Sized, [src]1.35.0

Splits 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

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]);

Trait Implementations

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

ⓘImportant traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized, 
    type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized, 
    type Item = <I as Iterator>::Item;
impl<'_, R: Read + ?Sized> Read for &'_ mut R
impl<'_, W: Write + ?Sized> Write for &'_ mut W

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

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

type Target = T

The resulting type after dereferencing.

ⓘImportant traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized, 
    type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized, 
    type Item = <I as Iterator>::Item;
impl<'_, R: Read + ?Sized> Read for &'_ mut R
impl<'_, W: Write + ?Sized> Write for &'_ mut W

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

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

Auto Trait Implementations

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

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

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

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

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

Blanket Implementations

impl<T, U> TryFrom<U> for T where
    U: Into<T>, [src]

type Error = Infallible

The type returned in the event of a conversion error.

impl<T, U> Into<U> for T where
    U: From<T>, [src]

impl<T> From<T> for T[src]

impl<T, U> TryInto<U> for T where
    U: TryFrom<T>, [src]

type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.

impl<T> Borrow<T> for T where
    T: ?Sized, [src]

ⓘImportant traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized, 
    type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized, 
    type Item = <I as Iterator>::Item;
impl<'_, R: Read + ?Sized> Read for &'_ mut R
impl<'_, W: Write + ?Sized> Write for &'_ mut W

impl<T> BorrowMut<T> for T where
    T: ?Sized, [src]

ⓘImportant traits for &'_ mut F
impl<'_, F> Future for &'_ mut F where
    F: Unpin + Future + ?Sized, 
    type Output = <F as Future>::Output;
impl<'_, I> Iterator for &'_ mut I where
    I: Iterator + ?Sized, 
    type Item = <I as Iterator>::Item;
impl<'_, R: Read + ?Sized> Read for &'_ mut R
impl<'_, W: Write + ?Sized> Write for &'_ mut W

impl<T> Any for T where
    T: 'static + ?Sized, [src]

impl<T> ToString for T where
    T: Display + ?Sized, [src]

© 2010 The Rust Project Developers
Licensed under the Apache License, Version 2.0 or the MIT license, at your option.
https://doc.rust-lang.org/std/cell/struct.RefMut.html