1.0.0[−][src]Struct core_futures_stateless::cell::Cell
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);
See the module-level documentation for more.
Methods
impl<T> Cell<T> where
T: Copy,
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T: Copy,
pub fn get(&self) -> T
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Returns a copy of the contained value.
Examples
use std::cell::Cell; let c = Cell::new(5); let five = c.get();
pub fn update<F>(&self, f: F) -> T where
F: FnOnce(T) -> T,
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F: FnOnce(T) -> T,
cell_update
)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);
impl<T> Cell<T>
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pub const fn new(value: T) -> Cell<T>
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pub fn set(&self, val: T)
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pub fn swap(&self, other: &Cell<T>)
1.17.0[src]
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());
pub fn replace(&self, val: T) -> T
1.17.0[src]
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);
pub fn into_inner(self) -> T
1.17.0[src]
Unwraps the value.
Examples
use std::cell::Cell; let c = Cell::new(5); let five = c.into_inner(); assert_eq!(five, 5);
impl<T> Cell<T> where
T: ?Sized,
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T: ?Sized,
pub const fn as_ptr(&self) -> *mut T
1.12.0[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();
pub fn get_mut(&mut self) -> &mut T
1.11.0[src]
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);
pub fn from_mut(t: &mut T) -> &Cell<T>
1.37.0[src]
Returns a &Cell<T>
from a &mut T
Examples
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);
impl<T> Cell<T> where
T: Default,
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T: Default,
pub fn take(&self) -> T
1.17.0[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);
impl<T> Cell<[T]>
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pub fn as_slice_of_cells(&self) -> &[Cell<T>]
1.37.0[src]
Returns a &[Cell<T>]
from a &Cell<[T]>
Examples
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);
Trait Implementations
impl<T> PartialOrd<Cell<T>> for Cell<T> where
T: Copy + PartialOrd<T>,
1.10.0[src]
T: Copy + PartialOrd<T>,
fn partial_cmp(&self, other: &Cell<T>) -> Option<Ordering>
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fn lt(&self, other: &Cell<T>) -> bool
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fn le(&self, other: &Cell<T>) -> bool
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fn gt(&self, other: &Cell<T>) -> bool
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fn ge(&self, other: &Cell<T>) -> bool
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impl<T> Default for Cell<T> where
T: Default,
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T: Default,
impl<T> Eq for Cell<T> where
T: Copy + Eq,
1.2.0[src]
T: Copy + Eq,
impl<T> Clone for Cell<T> where
T: Copy,
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T: Copy,
fn clone(&self) -> Cell<T>
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fn clone_from(&mut self, source: &Self)
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Performs copy-assignment from source
. Read more
impl<T> Debug for Cell<T> where
T: Copy + Debug,
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T: Copy + Debug,
impl<T> Ord for Cell<T> where
T: Copy + Ord,
1.10.0[src]
T: Copy + Ord,
fn cmp(&self, other: &Cell<T>) -> Ordering
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fn max(self, other: Self) -> Self
1.21.0[src]
Compares and returns the maximum of two values. Read more
fn min(self, other: Self) -> Self
1.21.0[src]
Compares and returns the minimum of two values. Read more
fn clamp(self, min: Self, max: Self) -> Self
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clamp
)Restrict a value to a certain interval. Read more
impl<T> Send for Cell<T> where
T: Send + ?Sized,
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T: Send + ?Sized,
impl<T> PartialEq<Cell<T>> for Cell<T> where
T: Copy + PartialEq<T>,
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T: Copy + PartialEq<T>,
fn eq(&self, other: &Cell<T>) -> bool
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#[must_use]
fn ne(&self, other: &Rhs) -> bool
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This method tests for !=
.
impl<T, U> CoerceUnsized<Cell<U>> for Cell<T> where
T: CoerceUnsized<U>,
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T: CoerceUnsized<U>,
impl<T> From<T> for Cell<T>
1.12.0[src]
impl<T> !Sync for Cell<T> where
T: ?Sized,
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T: ?Sized,
Auto Trait Implementations
Blanket Implementations
impl<T, U> TryFrom<U> for T where
U: Into<T>,
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U: Into<T>,
type Error = Infallible
The type returned in the event of a conversion error.
fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>
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impl<T, U> Into<U> for T where
U: From<T>,
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U: From<T>,
impl<T> From<T> for T
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impl<T, U> TryInto<U> for T where
U: TryFrom<T>,
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U: TryFrom<T>,
type Error = <U as TryFrom<T>>::Error
The type returned in the event of a conversion error.
fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>
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impl<T> Borrow<T> for T where
T: ?Sized,
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T: ?Sized,
impl<T> BorrowMut<T> for T where
T: ?Sized,
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T: ?Sized,
fn borrow_mut(&mut self) -> &mut T
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impl<T> Any for T where
T: 'static + ?Sized,
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T: 'static + ?Sized,