Trait futures_lite::future::FutureExt
source · 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 race<F>(self, other: F) -> Race<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 { ... }
}
Expand description
Extension trait for Future
.
Provided Methods§
sourcefn poll(&mut self, cx: &mut Context<'_>) -> Poll<Self::Output>where
Self: Unpin,
fn poll(&mut self, cx: &mut Context<'_>) -> Poll<Self::Output>where
Self: Unpin,
A convenience for calling Future::poll()
on !
Unpin
types.
sourcefn or<F>(self, other: F) -> Or<Self, F> ⓘ
fn or<F>(self, other: F) -> Or<Self, F> ⓘ
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);
sourcefn race<F>(self, other: F) -> Race<Self, F> ⓘ
fn race<F>(self, other: F) -> Race<Self, F> ⓘ
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;
sourcefn catch_unwind(self) -> CatchUnwind<Self> ⓘwhere
Self: Sized + UnwindSafe,
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());
sourcefn boxed<'a>(self) -> Pin<Box<dyn Future<Output = Self::Output> + Send + 'a>>
fn boxed<'a>(self) -> Pin<Box<dyn Future<Output = Self::Output> + 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()];
sourcefn boxed_local<'a>(self) -> Pin<Box<dyn Future<Output = Self::Output> + 'a>>where
Self: Sized + 'a,
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()];