1.0.0[][src]Struct std::cell::Cell

#[repr(transparent)]
pub struct Cell<T> where
    T: ?Sized
{ /* fields omitted */ }

A mutable memory location.

Examples

In this example, you can see that Cell<T> enables mutation inside an immutable struct. In other words, it enables "interior mutability".

use std::cell::Cell;

struct SomeStruct {
    regular_field: u8,
    special_field: Cell<u8>,
}

let my_struct = SomeStruct {
    regular_field: 0,
    special_field: Cell::new(1),
};

let new_value = 100;

// ERROR: `my_struct` is immutable
// my_struct.regular_field = new_value;

// WORKS: although `my_struct` is immutable, `special_field` is a `Cell`,
// which can always be mutated
my_struct.special_field.set(new_value);
assert_eq!(my_struct.special_field.get(), new_value);Run

See the module-level documentation for more.

Methods

impl<T> Cell<T> where
    T: Copy
[src]

Returns a copy of the contained value.

Examples

use std::cell::Cell;

let c = Cell::new(5);

let five = c.get();Run

🔬 This is a nightly-only experimental API. (cell_update #50186)

Updates the contained value using a function and returns the new value.

Examples

#![feature(cell_update)]

use std::cell::Cell;

let c = Cell::new(5);
let new = c.update(|x| x + 1);

assert_eq!(new, 6);
assert_eq!(c.get(), 6);Run

impl<T> Cell<T>
[src]

Creates a new Cell containing the given value.

Examples

use std::cell::Cell;

let c = Cell::new(5);Run

Sets the contained value.

Examples

use std::cell::Cell;

let c = Cell::new(5);

c.set(10);Run

Swaps the values of two Cells. Difference with std::mem::swap is that this function doesn't require &mut reference.

Examples

use std::cell::Cell;

let c1 = Cell::new(5i32);
let c2 = Cell::new(10i32);
c1.swap(&c2);
assert_eq!(10, c1.get());
assert_eq!(5, c2.get());Run

Replaces the contained value, and returns it.

Examples

use std::cell::Cell;

let cell = Cell::new(5);
assert_eq!(cell.get(), 5);
assert_eq!(cell.replace(10), 5);
assert_eq!(cell.get(), 10);Run

Unwraps the value.

Examples

use std::cell::Cell;

let c = Cell::new(5);
let five = c.into_inner();

assert_eq!(five, 5);Run

impl<T> Cell<T> where
    T: ?Sized
[src]

Returns a raw pointer to the underlying data in this cell.

Examples

use std::cell::Cell;

let c = Cell::new(5);

let ptr = c.as_ptr();Run

Important traits for &'_ mut I

Returns a mutable reference to the underlying data.

This call borrows Cell mutably (at compile-time) which guarantees that we possess the only reference.

Examples

use std::cell::Cell;

let mut c = Cell::new(5);
*c.get_mut() += 1;

assert_eq!(c.get(), 6);Run

🔬 This is a nightly-only experimental API. (as_cell #43038)

Returns a &Cell<T> from a &mut T

Examples

#![feature(as_cell)]
use std::cell::Cell;

let slice: &mut [i32] = &mut [1, 2, 3];
let cell_slice: &Cell<[i32]> = Cell::from_mut(slice);
let slice_cell: &[Cell<i32>] = cell_slice.as_slice_of_cells();

assert_eq!(slice_cell.len(), 3);Run

impl<T> Cell<T> where
    T: Default
[src]

Takes the value of the cell, leaving Default::default() in its place.

Examples

use std::cell::Cell;

let c = Cell::new(5);
let five = c.take();

assert_eq!(five, 5);
assert_eq!(c.into_inner(), 0);Run

impl<T> Cell<[T]>
[src]

Important traits for &'a [u8]

🔬 This is a nightly-only experimental API. (as_cell #43038)

Returns a &[Cell<T>] from a &Cell<[T]>

Examples

#![feature(as_cell)]
use std::cell::Cell;

let slice: &mut [i32] = &mut [1, 2, 3];
let cell_slice: &Cell<[i32]> = Cell::from_mut(slice);
let slice_cell: &[Cell<i32>] = cell_slice.as_slice_of_cells();

assert_eq!(slice_cell.len(), 3);Run

Trait Implementations

impl<T> Clone for Cell<T> where
    T: Copy
[src]

Performs copy-assignment from source. Read more

impl<T> PartialOrd<Cell<T>> for Cell<T> where
    T: Copy + PartialOrd<T>, 
1.10.0
[src]

impl<T> Ord for Cell<T> where
    T: Copy + Ord
1.10.0
[src]

Compares and returns the maximum of two values. Read more

Compares and returns the minimum of two values. Read more

impl<T> Eq for Cell<T> where
    T: Copy + Eq
1.2.0
[src]

impl<T> PartialEq<Cell<T>> for Cell<T> where
    T: Copy + PartialEq<T>, 
[src]

This method tests for !=.

impl<T, U> CoerceUnsized<Cell<U>> for Cell<T> where
    T: CoerceUnsized<U>, 
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impl<T> From<T> for Cell<T>
1.12.0
[src]

impl<T> Default for Cell<T> where
    T: Default
[src]

Creates a Cell<T>, with the Default value for T.

impl<T> Debug for Cell<T> where
    T: Copy + Debug
[src]

impl<T> !Sync for Cell<T> where
    T: ?Sized
[src]

impl<T> Send for Cell<T> where
    T: Send + ?Sized
[src]

Blanket Implementations

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

🔬 This is a nightly-only experimental API. (try_from #33417)

The type returned in the event of a conversion error.

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

🔬 This is a nightly-only experimental API. (try_from #33417)

The type returned in the event of a conversion error.

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

impl<T> Borrow for T where
    T: ?Sized
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impl<T> BorrowMut for T where
    T: ?Sized
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impl<T> Any for T where
    T: 'static + ?Sized
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impl<T> ToOwned for T where
    T: Clone
[src]