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

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

A mutable memory location.

Examples

Here you can see how using Cell<T> allows to use mutable field inside immutable struct (which is also called '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, because my_struct is immutable
// my_struct.regular_field = new_value;

// WORKS, although `my_struct` is immutable, field `special_field` is mutable because it is Cell
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 &'a 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> Ord for Cell<T> where
    T: Copy + Ord
1.10.0
[src]

This method returns an Ordering between self and other. Read more

Compares and returns the maximum of two values. Read more

Compares and returns the minimum of two values. Read more

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

Formats the value using the given formatter. 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 self and other values to be equal, and is used by ==. Read more

This method tests for !=.

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

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

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

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

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

impl<T> From<T> for Cell<T>
1.12.0
[src]

Performs the conversion.

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

Returns a copy of the value. Read more

Performs copy-assignment from source. Read more

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

This method returns an ordering between self and other values if one exists. Read more

This method tests less than (for self and other) and is used by the < operator. Read more

This method tests less than or equal to (for self and other) and is used by the <= operator. Read more

This method tests greater than (for self and other) and is used by the > operator. Read more

This method tests greater than or equal to (for self and other) and is used by the >= operator. Read more

Blanket Implementations

impl<T> From for T
[src]

Performs the conversion.

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.

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

Performs the conversion.

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.

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

Performs the conversion.

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

Performs the conversion.

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

Important traits for &'a mut I

Immutably borrows from an owned value. Read more

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

Important traits for &'a mut I

Mutably borrows from an owned value. Read more

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

🔬 This is a nightly-only experimental API. (get_type_id #27745)

this method will likely be replaced by an associated static

Gets the TypeId of self. Read more

impl<T> ToOwned for T where
    T: Clone
[src]

Creates owned data from borrowed data, usually by cloning. Read more

🔬 This is a nightly-only experimental API. (toowned_clone_into #41263)

recently added

Uses borrowed data to replace owned data, usually by cloning. Read more