Struct Once

pub struct Once<T: Send> {
    cell: UnsafeCell<MaybeUninit<T>>,
    state: AtomicU8,
}

Variable that is initialized exactly once.

Fields

cell: UnsafeCell<MaybeUninit<T>>

state: AtomicU8

Implementations

impl<T: Send> Once<T>

pub const fn new() -> Self

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

Set the value if it is not initialized already. This call succeeds only once.

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

Get the value if it is initialized.

pub fn get_or_init(&self, f: impl FnOnce() -> T) -> &T

Get the value if it is initialized, otherwise initialize it.

Trait Implementations

impl<T: Send> Deref for Once<T>

type Target = T

The resulting type after dereferencing.

fn deref(&self) -> &Self::Target

Dereferences the value.

impl<T: Send> Drop for Once<T>

fn drop(&mut self)

Executes the destructor for this type.

impl<T: Send> Send for Once<T>

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