Macro ready

macro_rules! ready {
    ($e:expr $(,)?) => { ... };
}

Unwraps Poll<T> or returns Pending.

Examples

use futures_lite::{future, prelude::*, ready};
use std::pin::Pin;
use std::task::{Context, Poll};

fn do_poll(cx: &mut Context<'_>) -> Poll<()> {
    let mut fut = future::ready(42);
    let fut = Pin::new(&mut fut);

    let num = ready!(fut.poll(cx));
    // ... use num

    Poll::Ready(())
}

The ready! call expands to:

let num = match fut.poll(cx) {
    Poll::Ready(t) => t,
    Poll::Pending => return Poll::Pending,
};