Trait futures_lite::future::FutureExt

source · [−]
pub trait FutureExt: Future {
    fn poll(&mut self, cx: &mut Context<'_>) -> Poll<Self::Output>
    where
        Self: Unpin,
    { ... }

    fn or<F>(self, other: F) -> Or<Self, F>ⓘNotable traits for Or<F1, F2>impl<T, F1, F2> Future for Or<F1, F2> where
    F1: Future<Output = T>,
    F2: Future<Output = T>,     type Output = T;
    where
        Self: Sized,
        F: Future<Output = Self::Output>,
    { ... }

    fn race<F>(self, other: F) -> Race<Self, F>ⓘNotable traits for Race<F1, F2>impl<T, F1, F2> Future for Race<F1, F2> where
    F1: Future<Output = T>,
    F2: Future<Output = T>,     type Output = T;
    where
        Self: Sized,
        F: Future<Output = Self::Output>,
    { ... }

    fn catch_unwind(self) -> CatchUnwind<Self>ⓘNotable traits for CatchUnwind<F>impl<F: Future + UnwindSafe> Future for CatchUnwind<F>    type Output = Result<F::Output, Box<dyn Any + Send>>;
    where
        Self: Sized + UnwindSafe,
    { ... }

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

    fn boxed_local<'a>(self) -> Pin<Box<dyn Future<Output = Self::Output> + 'a>>
    where
        Self: Sized + 'a,
    { ... }
}
Expand description

Extension trait for Future.

Provided methods

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

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);

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;

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());

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()];

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()];

Implementors