Struct OnceCell 

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

Lock-free thread-safe cell which can be written to only once.

Implementations

impl<T> OnceCell<T>

pub const fn new() -> Self

Creates a new empty cell.

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

Sets the contents of this cell to value.

Returns Ok(()) if the cell’s value was set by this call.

pub fn set_with<F: FnOnce() -> T>(&self, ctor: F) -> Result<(), F>

Sets the contents of this cell to value returned by ctor call.

The ctor is called only if the cell’s value is going set by this call. Otherwice ctor returned in Err(..).

Panics

If ctor panics, the panic is propagated to the caller, and the cell remains uninitialized.

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

Gets the pointer to the underlying value.

Returns None if the cell is empty.

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

Gets the reference to the underlying value.

Returns None if the cell is empty, or being initialized.

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

Gets the mutable reference to the underlying value.

Returns None if the cell is empty.

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

Takes the value out of this cell, moving it back to an uninitialized state.

Has no effect and returns None if the cell hasn’t been initialized.

pub fn into_inner(self) -> Option<T>

Consumes the cell, returning the wrapped value.

Returns None if the cell was empty.

Trait Implementations

impl<T> Drop for OnceCell<T>

fn drop(&mut self)

Executes the destructor for this type.

impl<T: RefUnwindSafe + UnwindSafe> RefUnwindSafe for OnceCell<T>

impl<T: Send> Send for OnceCell<T>

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

impl<T: UnwindSafe> UnwindSafe for OnceCell<T>