Struct kernel::sync::once::OnceLock

pub struct OnceLock<T> {
    once: Once,
    value: UnsafeCell<MaybeUninit<T>>,
    _marker: PhantomData<T>,
}

Fields

once: Once

value: UnsafeCell<MaybeUninit<T>>

_marker: PhantomData<T>

PhantomData to make sure dropck understands we’re dropping T in our Drop impl.

use std::sync::OnceLock;

struct A<'a>(&'a str);

impl<'a> Drop for A<'a> {
    fn drop(&mut self) {}
}

let cell = OnceLock::new();
{
    let s = String::new();
    let _ = cell.set(A(&s));
}

Implementations

impl<T> OnceLock<T>

pub const fn new() -> Self

pub fn set(&self, value: T) -> Result<(), T>

pub fn get(&self) -> &T

pub fn try_get(&self) -> Option<&T>

pub fn get_or_init<F>(&self, f: F) -> &T

where F: FnOnce() -> T,

pub fn get_or_try_init<F, E>(&self, f: F) -> Result<&T, E>

where F: FnOnce() -> Result<T, E>,

fn init<F, E>(&self, f: F) -> Result<(), E>

where F: FnOnce() -> Result<T, E>,

unsafe fn get_unchecked(&self) -> &T

fn is_completed(&self) -> bool

Trait Implementations

impl<T: Clone> Clone for OnceLock<T>

fn clone(&self) -> OnceLock<T>

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<T: Debug> Debug for OnceLock<T>

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl<T> Drop for OnceLock<T>

fn drop(&mut self)

Executes the destructor for this type.

impl<T: Send> Send for OnceLock<T>

impl<T: Sync + Send> Sync for OnceLock<T>