core::cell::RefMut - Rust
Description: API documentation for the Rust `RefMut` struct in crate `core`.
Keywords: rust, rustlang, rust-lang, RefMut

# Struct core::cell::RefMut 1.0.0[−][src]

    pub struct RefMut<'b, T: ?Sized + 'b> { /* 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: ?Sized> RefMut<'b, T>`

[src]

####

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

1.8.0
[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

####

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

[src]

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

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

The underlying `RefCell` will remain mutably borrowed until both returned `RefMut`s 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: ?Sized> Deref for RefMut<'b, T>`

[src]

#### `type Target = T`

The resulting type after dereferencing.

####

`fn deref(&self) -> &T`

[src]

Dereferences the value.

###

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

[src]

####

`fn deref_mut(&mut self) -> &mut T`

[src]

Mutably dereferences the value.

###

`impl<'b, T: ?Sized + Unsize<U>, U: ?Sized> CoerceUnsized<RefMut<'b, U>> for RefMut<'b, T>`

[src]

###

`impl<'a, T: ?Sized + Display> Display for RefMut<'a, T>`

1.20.0
[src]

####

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

[src]

Formats the value using the given formatter. Read more

###

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

[src]

####

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

[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>`

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