Struct OnceMut 

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

Like OnceCell but with exclusive mutable access to its content.

Implementations

impl<T> OnceMut<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 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 get_ptr(&self) -> Option<*mut T>

Gets the pointer to the underlying value.

Returns None if the cell is empty.

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

Gets the mutable reference to the underlying value.

The main difference from OnceCell::get_mut is that self is taken as immutable.

After this call returns Some(..), all subsequent calls will return None, and there is no way to obtain mutable reference again.

pub fn lock(&self) -> Option<LockGuard<'_, T>>

Gets a guarded mutable reference to the underlying value.

Only one guard of the same value can exist at the same time.

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

Consumes the cell, returning the wrapped value.

Returns None if the cell was empty.