Struct OnceLock 

pub struct OnceLock<T> { /* private fields */ }

A wrapper around a OnceCell that implements Collect.

Only provides safe read access to the wrapped OnceCell, full write access requires unsafety.

If the OnceLock is directly held in a Gc pointer, safe mutable access is provided, since methods on Gc can ensure that the write barrier is called.

Implementations

impl<T> OnceLock<T>

pub fn new() -> Self

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

pub fn get_mut(&mut self) -> Option<&mut T>

Trait Implementations

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

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

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl<'gc, T: Collect<'gc>> Collect<'gc> for OnceLock<T>

const NEEDS_TRACE: bool = T::NEEDS_TRACE

As an optimization, if this type can never hold a Gc pointer and trace is unnecessary to call, you may set this to false. The default value is true, signaling that Collect::trace must be called.

fn trace<C: Trace<'gc>>(&self, cc: &mut C)

Must call Trace::trace_gc (resp. Trace::trace_gc_weak) on all directly owned Gc (resp. GcWeak) pointers. If this type holds inner types that implement Collect, a valid implementation would simply call Trace::trace on all the held values to ensure this.

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

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

Formats the value using the given formatter.

impl<T> Default for OnceLock<T>

fn default() -> Self

Returns the “default value” for a type.

impl<T: Eq> Eq for OnceLock<T>

impl<T> From<OnceCell<T>> for OnceLock<T>

fn from(cell: OnceCell<T>) -> Self

Converts to this type from the input type.

impl<T> From<T> for OnceLock<T>

fn from(t: T) -> Self

Converts to this type from the input type.

impl<T: PartialEq> PartialEq for OnceLock<T>

fn eq(&self, other: &OnceLock<T>) -> bool

Equality operator ==.

fn ne(&self, other: &Rhs) -> bool

Inequality operator !=.

impl<T: PartialEq> StructuralPartialEq for OnceLock<T>

impl<T> Unlock for OnceLock<T>

type Unlocked = OnceCell<T>

This will typically be a cell-like type providing some sort of interior mutability.

unsafe fn unlock_unchecked(&self) -> &Self::Unlocked

Provides unsafe access to the unlocked type, without triggering a write barrier.