Function futures_util::future::lazy

source · [−]

pub fn lazy<F, R>(f: F) -> Lazy<F>ⓘNotable traits for Lazy<F>impl<F, R> Future for Lazy<F>where
    F: FnOnce(&mut Context<'_>) -> R,    type Output = R;where
    F: FnOnce(&mut Context<'_>) -> R,

Expand description

Creates a new future that allows delayed execution of a closure.

The provided closure is only run once the future is polled.

Examples

use futures::future;

let a = future::lazy(|_| 1);
assert_eq!(a.await, 1);

let b = future::lazy(|_| -> i32 {
    panic!("oh no!")
});
drop(b); // closure is never run