pub struct Cell<T> { /* fields omitted */ }
A mutable memory location.
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);
See the module-level documentation for more.
impl<T> Cell<T> where
T: Copy,
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fn get(&self) -> T
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Returns a copy of the contained value.
use std::cell::Cell; let c = Cell::new(5); let five = c.get();
impl<T> Cell<T>
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const fn new(value: T) -> Cell<T>
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Creates a new Cell
containing the given value.
use std::cell::Cell; let c = Cell::new(5);
fn as_ptr(&self) -> *mut T
Returns a raw pointer to the underlying data in this cell.
use std::cell::Cell; let c = Cell::new(5); let ptr = c.as_ptr();
fn get_mut(&mut self) -> &mut T
Returns a mutable reference to the underlying data.
This call borrows Cell
mutably (at compile-time) which guarantees that we possess the only reference.
use std::cell::Cell; let mut c = Cell::new(5); *c.get_mut() += 1; assert_eq!(c.get(), 6);
fn set(&self, val: T)
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Sets the contained value.
use std::cell::Cell; let c = Cell::new(5); c.set(10);
fn swap(&self, other: &Cell<T>)
Swaps the values of two Cells. Difference with std::mem::swap
is that this function doesn't require &mut
reference.
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());
fn replace(&self, val: T) -> T
Replaces the contained value, and returns it.
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);
fn into_inner(self) -> T
Unwraps the value.
use std::cell::Cell; let c = Cell::new(5); let five = c.into_inner(); assert_eq!(five, 5);
impl<T> Cell<T> where
T: Default,
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fn take(&self) -> T
Takes the value of the cell, leaving Default::default()
in its place.
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> Default for Cell<T> where
T: Default,
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fn default() -> Cell<T>
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Creates a Cell<T>
, with the Default
value for T.
impl<T> Clone for Cell<T> where
T: Copy,
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fn clone(&self) -> Cell<T>
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Returns a copy of the value. Read more
fn clone_from(&mut self, source: &Self)
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Performs copy-assignment from source
. Read more
impl<T> PartialOrd<Cell<T>> for Cell<T> where
T: Copy + PartialOrd<T>,
fn partial_cmp(&self, other: &Cell<T>) -> Option<Ordering>
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This method returns an ordering between self
and other
values if one exists. Read more
fn lt(&self, other: &Cell<T>) -> bool
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This method tests less than (for self
and other
) and is used by the <
operator. Read more
fn le(&self, other: &Cell<T>) -> bool
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This method tests less than or equal to (for self
and other
) and is used by the <=
operator. Read more
fn gt(&self, other: &Cell<T>) -> bool
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This method tests greater than (for self
and other
) and is used by the >
operator. Read more
fn ge(&self, other: &Cell<T>) -> bool
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This method tests greater than or equal to (for self
and other
) and is used by the >=
operator. Read more
impl<T> Eq for Cell<T> where
T: Copy + Eq,
impl<T> From<T> for Cell<T>
fn from(t: T) -> Cell<T>
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Performs the conversion.
impl<T> Send for Cell<T> where
T: Send,
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impl<T, U> CoerceUnsized<Cell<U>> for Cell<T> where
T: CoerceUnsized<U>,
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impl<T> !Sync for Cell<T>
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impl<T> Ord for Cell<T> where
T: Copy + Ord,
fn cmp(&self, other: &Cell<T>) -> Ordering
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This method returns an Ordering
between self
and other
. Read more
fn max(self, other: Self) -> Self
Compares and returns the maximum of two values. Read more
fn min(self, other: Self) -> Self
Compares and returns the minimum of two values. Read more
impl<T> PartialEq<Cell<T>> for Cell<T> where
T: Copy + PartialEq<T>,
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fn eq(&self, other: &Cell<T>) -> bool
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This method tests for self
and other
values to be equal, and is used by ==
. Read more
fn ne(&self, other: &Rhs) -> bool
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This method tests for !=
.
impl<T> Debug for Cell<T> where
T: Copy + Debug,
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fn fmt(&self, f: &mut Formatter) -> Result<(), Error>
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Formats the value using the given formatter. Read more
© 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.Cell.html