Struct enso_prelude::Cell 1.0.0[−][src]
#[repr(transparent)]pub struct Cell<T> where
T: ?Sized, { /* fields omitted */ }
Expand description
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.
Implementations
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());
Replaces the contained value with val
, and returns the old contained value.
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);
Unwraps the value.
Examples
use std::cell::Cell; let c = Cell::new(5); let five = c.into_inner(); assert_eq!(five, 5);
Returns a copy of the contained value.
Examples
use std::cell::Cell; let c = Cell::new(5); let five = c.get();
🔬 This is a nightly-only experimental API. (cell_update
)
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);
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();
Returns a mutable reference to the underlying data.
This call borrows Cell
mutably (at compile-time) which guarantees
that we possess the only reference.
However be cautious: this method expects self
to be mutable, which is
generally not the case when using a Cell
. If you require interior
mutability by reference, consider using RefCell
which provides
run-time checked mutable borrows through its borrow_mut
method.
Examples
use std::cell::Cell; let mut c = Cell::new(5); *c.get_mut() += 1; assert_eq!(c.get(), 6);
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);
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
type Epsilon = <T as AbsDiffEq<T>>::Epsilon
type Epsilon = <T as AbsDiffEq<T>>::Epsilon
Used for specifying relative comparisons.
pub fn default_epsilon() -> <T as AbsDiffEq<T>>::Epsilon
pub fn default_epsilon() -> <T as AbsDiffEq<T>>::Epsilon
The default tolerance to use when testing values that are close together. Read more
pub fn abs_diff_eq(
&self,
other: &Cell<T>,
epsilon: <T as AbsDiffEq<T>>::Epsilon
) -> bool
pub fn abs_diff_eq(
&self,
other: &Cell<T>,
epsilon: <T as AbsDiffEq<T>>::Epsilon
) -> bool
A test for equality that uses the absolute difference to compute the approximate equality of two numbers. Read more
fn abs_diff_ne(&self, other: &Rhs, epsilon: Self::Epsilon) -> bool
fn abs_diff_ne(&self, other: &Rhs, epsilon: Self::Epsilon) -> bool
The inverse of [AbsDiffEq::abs_diff_eq
].
pub fn deserialize<D>(
deserializer: D
) -> Result<Cell<T>, <D as Deserializer<'de>>::Error> where
D: Deserializer<'de>,
pub fn deserialize<D>(
deserializer: D
) -> Result<Cell<T>, <D as Deserializer<'de>>::Error> where
D: Deserializer<'de>,
Deserialize this value from the given Serde deserializer. 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
pub fn default_max_relative() -> <T as AbsDiffEq<T>>::Epsilon
pub fn default_max_relative() -> <T as AbsDiffEq<T>>::Epsilon
The default relative tolerance for testing values that are far-apart. Read more
pub fn relative_eq(
&self,
other: &Cell<T>,
epsilon: <T as AbsDiffEq<T>>::Epsilon,
max_relative: <T as AbsDiffEq<T>>::Epsilon
) -> bool
pub fn relative_eq(
&self,
other: &Cell<T>,
epsilon: <T as AbsDiffEq<T>>::Epsilon,
max_relative: <T as AbsDiffEq<T>>::Epsilon
) -> bool
A test for equality that uses a relative comparison if the values are far apart.
fn relative_ne(
&self,
other: &Rhs,
epsilon: Self::Epsilon,
max_relative: Self::Epsilon
) -> bool
fn relative_ne(
&self,
other: &Rhs,
epsilon: Self::Epsilon,
max_relative: Self::Epsilon
) -> bool
The inverse of [RelativeEq::relative_eq
].
pub fn serialize<S>(
&self,
serializer: S
) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error> where
S: Serializer,
pub fn serialize<S>(
&self,
serializer: S
) -> Result<<S as Serializer>::Ok, <S as Serializer>::Error> where
S: Serializer,
Serialize this value into the given Serde serializer. Read more
pub fn default_max_ulps() -> u32
pub fn default_max_ulps() -> u32
The default ULPs to tolerate when testing values that are far-apart. Read more
A test for equality that uses units in the last place (ULP) if the values are far apart.
Auto Trait Implementations
impl<T> !RefUnwindSafe for Cell<T>
impl<T: ?Sized> UnwindSafe for Cell<T> where
T: UnwindSafe,
Blanket Implementations
Mutably borrows from an owned value. Read more
Updates the contained value using a function and returns the new value.
type Output = T
type Output = T
Should always be Self
The inverse inclusion map: attempts to construct self
from the equivalent element of its
superset. Read more
pub fn is_in_subset(&self) -> bool
pub fn is_in_subset(&self) -> bool
Checks if self
is actually part of its subset T
(and can be converted to it).
pub fn to_subset_unchecked(&self) -> SS
pub fn to_subset_unchecked(&self) -> SS
Use with care! Same as self.to_subset
but without any property checks. Always succeeds.
pub fn from_subset(element: &SS) -> SP
pub fn from_subset(element: &SS) -> SP
The inclusion map: converts self
to the equivalent element of its superset.