OnceBox - once

`impl<T> OnceBox<T>`

const fn new() -> Self

Creates a new empty cell.

fn with_value(value: Box<T>) -> Self

Creates a new cell with the given value.

fn get(self: &Self) -> Option<&T>

Gets a reference to the underlying value.

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

Sets the contents of this cell to value.

Returns Ok(()) if the cell was empty and Err(value) if it was full.

fn get_or_init<F>(self: &Self, f: F) -> &T where F: FnOnce() -> Box<T>

Gets the contents of the cell, initializing it with f if the cell was empty.

If several threads concurrently run get_or_init, more than one f can be called. However, all threads will return the same value, produced by some f.

fn get_or_try_init<F, E>(self: &Self, f: F) -> Result<&T, E> where F: FnOnce() -> Result<Box<T>, E>

Gets the contents of the cell, initializing it with f if the cell was empty. If the cell was empty and f failed, an error is returned.

If several threads concurrently run get_or_init, more than one f can be called. However, all threads will return the same value, produced by some f.

`impl<T> Any for OnceBox<T>`

fn type_id(self: &Self) -> TypeId

`impl<T> Borrow for OnceBox<T>`

fn borrow(self: &Self) -> &T

`impl<T> BorrowMut for OnceBox<T>`

fn borrow_mut(self: &mut Self) -> &mut T

`impl<T> CloneToUninit for OnceBox<T>`

unsafe fn clone_to_uninit(self: &Self, dest: *mut u8)

`impl<T> Debug for OnceBox<T>`

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

`impl<T> Default for OnceBox<T>`

fn default() -> Self

`impl<T> Drop for OnceBox<T>`

fn drop(self: &mut Self)

`impl<T> Freeze for OnceBox<T>`

`impl<T> From for OnceBox<T>`

fn from(t: T) -> T: Returns the argument unchanged.

`impl<T> RefUnwindSafe for OnceBox<T>`

`impl<T> Send for OnceBox<T>`

`impl<T> ToOwned for OnceBox<T>`

fn to_owned(self: &Self) -> T
fn clone_into(self: &Self, target: &mut T)

`impl<T> Unpin for OnceBox<T>`

`impl<T> UnsafeUnpin for OnceBox<T>`

`impl<T> UnwindSafe for OnceBox<T>`

`impl<T, U> Into for OnceBox<T>`

fn into(self: Self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of [From]<T> for U chooses to do.

`impl<T, U> TryFrom for OnceBox<T>`

fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

`impl<T, U> TryInto for OnceBox<T>`

fn try_into(self: Self) -> Result<U, <U as TryFrom<T>>::Error>

`impl<T: Clone> Clone for OnceBox<T>`

fn clone(self: &Self) -> Self

Struct `OnceBox`

Implementations