Trait FutureExt

pub trait FutureExt: Future {
    // Provided methods
    fn poll(&mut self, cx: &mut Context<'_>) -> Poll<Self::Output>
       where Self: Unpin { ... }
    fn or<F>(self, other: F) -> Or<Self, F> 
       where Self: Sized,
             F: Future<Output = Self::Output> { ... }
    fn catch_unwind(self) -> CatchUnwind<Self> 
       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 { ... }
}

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 Self: Sized, 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 catch_unwind(self) -> CatchUnwind<Self>

where Self: Sized + 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> + Send + 'a>>

where Self: Sized + 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: Sized + '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()];

Implementors

impl<F> FutureExt for F

where F: Future + ?Sized,