#[repr(transparent)]
pub struct Cell<T> where
T: ?Sized, { /* fields omitted */ }
Expand description
A mutable memory location.
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;
my_struct.special_field.set(new_value);
assert_eq!(my_struct.special_field.get(), new_value);
Run
See the module-level documentation for more.
1.0.0 (const: 1.24.0)[src]
Creates a new Cell
containing the given value.
use std::cell::Cell;
let c = Cell::new(5);
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Sets the contained value.
use std::cell::Cell;
let c = Cell::new(5);
c.set(10);
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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());
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Replaces the contained value with val
, and returns the old contained value.
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);
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Unwraps the value.
use std::cell::Cell;
let c = Cell::new(5);
let five = c.into_inner();
assert_eq!(five, 5);
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Returns a copy of the contained value.
use std::cell::Cell;
let c = Cell::new(5);
let five = c.get();
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🔬 This is a nightly-only experimental API. (
cell_update
#50186)
Updates the contained value using a function and returns the new value.
#![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);
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1.12.0 (const: 1.32.0)[src]
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();
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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);
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Returns a &Cell<T>
from a &mut T
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);
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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);
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Returns a &[Cell<T>]
from a &Cell<[T]>
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);
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Performs copy-assignment from source
. Read more
Formats the value using the given formatter. Read more
Creates a Cell<T>
, with the Default
value for T.
Compares and returns the maximum of two values. Read more
Compares and returns the minimum of two values. Read more
Restrict a value to a certain interval. Read more
This method tests for self
and other
values to be equal, and is used
by ==
. Read more
This method tests for !=
.
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
Immutably borrows from an owned value. Read more
Mutably borrows from an owned value. Read more
The resulting type after obtaining ownership.
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
The type returned in the event of a conversion error.
The type returned in the event of a conversion error.