Struct futures::future::OptionFuture

#[must_use = "futures do nothing unless you `.await` or poll them"]
pub struct OptionFuture<F> { /* fields omitted */ }

A future representing a value which may or may not be present.

Created by the From implementation for Option.

Examples

use futures::future::OptionFuture;

let mut a: OptionFuture<_> = Some(async { 123 }).into();
assert_eq!(a.await, Some(123));

a = None.into();
assert_eq!(a.await, None);

Trait Implementations

impl<F> Clone for OptionFuture<F> where
    F: Clone, 

Important traits for OptionFuture<F>

impl<F> Future for OptionFuture<F> where
    F: Future,  type Output = Option<<F as Future>::Output>;

fn clone(&self) -> OptionFuture<F>

Returns a copy of the value.

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

Performs copy-assignment from source.

impl<F> Debug for OptionFuture<F> where
    F: Debug, 

fn fmt(&self, f: &mut Formatter) -> Result<(), Error>

Formats the value using the given formatter.

impl<T> From<Option<T>> for OptionFuture<T>

Important traits for OptionFuture<F>

impl<F> Future for OptionFuture<F> where
    F: Future,  type Output = Option<<F as Future>::Output>;

fn from(option: Option<T>) -> OptionFuture<T>

Performs the conversion.

impl<F> FusedFuture for OptionFuture<F> where
    F: FusedFuture, 

fn is_terminated(&self) -> bool

Returns true if the underlying future should no longer be polled.

impl<F> Future for OptionFuture<F> where
    F: Future, 

type Output = Option<<F as Future>::Output>

The type of value produced on completion.

fn poll(
    self: Pin<&mut OptionFuture<F>>,
    cx: &mut Context
) -> Poll<<OptionFuture<F> as Future>::Output>

Attempt to resolve the future to a final value, registering the current task for wakeup if the value is not yet available.