Trait smol::prelude::_

pub trait _: Future {
    fn poll(&mut self, cx: &mut Context<'_>) -> Poll<Self::Output>
    where
        Self: Unpin,
    { ... }
    fn or<F>(self, other: F) -> Or<Self, F>
    where
        F: Future<Output = Self::Output>,
    { ... }
    fn race<F>(self, other: F) -> Race<Self, F>
    where
        F: Future<Output = Self::Output>,
    { ... }
    fn catch_unwind(self) -> CatchUnwind<Self>
    where
        Self: UnwindSafe,
    { ... }
    fn boxed<'a>(
        self
    ) -> Pin<Box<dyn Future<Output = Self::Output> + 'a + Send>>
    where
        Self: Send + 'a,
    { ... }
    fn boxed_local<'a>(self) -> Pin<Box<dyn Future<Output = Self::Output> + 'a>>
    where
        Self: 'a,
    { ... }
}

Extension trait for Future.

Provided methods

fn poll(&mut self, cx: &mut Context<'_>) -> Poll<Self::Output> where
    Self: Unpin, 

A convenience for calling Future::poll() on !Unpin types.

fn or<F>(self, other: F) -> Or<Self, F> where
    F: Future<Output = Self::Output>, 

Returns the result of self or other future, preferring self if both are ready.

If you need to treat the two futures fairly without a preference for either, use the race() function or the FutureExt::race() method.

Examples

use futures_lite::future::{pending, ready, FutureExt};

assert_eq!(ready(1).or(pending()).await, 1);
assert_eq!(pending().or(ready(2)).await, 2);

// The first future wins.
assert_eq!(ready(1).or(ready(2)).await, 1);

fn race<F>(self, other: F) -> Race<Self, F> where
    F: Future<Output = Self::Output>, 

Returns the result of self or other future, with no preference if both are ready.

Each time Race is polled, the two inner futures are polled in random order. Therefore, no future takes precedence over the other if both can complete at the same time.

If you have preference for one of the futures, use the or() function or the FutureExt::or() method.

Examples

use futures_lite::future::{pending, ready, FutureExt};

assert_eq!(ready(1).race(pending()).await, 1);
assert_eq!(pending().race(ready(2)).await, 2);

// One of the two futures is randomly chosen as the winner.
let res = ready(1).race(ready(2)).await;

fn catch_unwind(self) -> CatchUnwind<Self> where
    Self: UnwindSafe, 

Catches panics while polling the future.

Examples

use futures_lite::future::FutureExt;

let fut1 = async {}.catch_unwind();
let fut2 = async { panic!() }.catch_unwind();

assert!(fut1.await.is_ok());
assert!(fut2.await.is_err());

fn boxed<'a>(self) -> Pin<Box<dyn Future<Output = Self::Output> + 'a + Send>> where
    Self: Send + 'a, 

Boxes the future and changes its type to dyn Future + Send + 'a.

Examples

use futures_lite::future::{self, FutureExt};

let a = future::ready('a');
let b = future::pending();

// Futures of different types can be stored in
// the same collection when they are boxed:
let futures = vec![a.boxed(), b.boxed()];

fn boxed_local<'a>(self) -> Pin<Box<dyn Future<Output = Self::Output> + 'a>> where
    Self: 'a, 

Boxes the future and changes its type to dyn Future + 'a.

Examples

use futures_lite::future::{self, FutureExt};

let a = future::ready('a');
let b = future::pending();

// Futures of different types can be stored in
// the same collection when they are boxed:
let futures = vec![a.boxed_local(), b.boxed_local()];

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Implementors

impl<F> FutureExt for F where
    F: Future + ?Sized, 

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