#[repr(transparent)]
pub struct Cell<T> where
T: ?Sized, { /* fields omitted */ }
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);
See the module-level documentation for more.
Returns a copy of the contained value.
use std::cell::Cell;
let c = Cell::new(5);
let five = c.get();
🔬 This is a nightly-only experimental API. (cell_update
)
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);
Creates a new Cell
containing the given value.
use std::cell::Cell;
let c = Cell::new(5);
Sets the contained value.
use std::cell::Cell;
let c = Cell::new(5);
c.set(10);
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());
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);
Unwraps the value.
use std::cell::Cell;
let c = Cell::new(5);
let five = c.into_inner();
assert_eq!(five, 5);
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();
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);
🔬 This is a nightly-only experimental API. (as_cell
)
Returns a &Cell<T>
from a &mut T
#![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);
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);
🔬 This is a nightly-only experimental API. (as_cell
)
Returns a &[Cell<T>]
from a &Cell<[T]>
#![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);
Performs copy-assignment from source
. Read more
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
This method returns an Ordering
between self
and other
. Read more
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
This method tests for self
and other
values to be equal, and is used by ==
. Read more
This method tests for !=
.
Formats the value using the given formatter. Read more
Creates a Cell<T>
, with the Default
value for T.
type Owned = T
Creates owned data from borrowed data, usually by cloning. Read more
🔬 This is a nightly-only experimental API. (toowned_clone_into
)
recently added
Uses borrowed data to replace owned data, usually by cloning. Read more
type Error = !
🔬 This is a nightly-only experimental API. (try_from
)
The type returned in the event of a conversion error.
🔬 This is a nightly-only experimental API. (try_from
)
Immutably borrows from an owned value. Read more
🔬 This is a nightly-only experimental API. (get_type_id
)
this method will likely be replaced by an associated static
type Error = <U as TryFrom<T>>::Error
🔬 This is a nightly-only experimental API. (try_from
)
The type returned in the event of a conversion error.
🔬 This is a nightly-only experimental API. (try_from
)
Mutably borrows from an owned value. Read more