Macro futures::try_join

macro_rules! try_join {
    ( $ ( $ fut : ident ) , * ) => { ... };
}

Polls multiple futures simultaneously, resolving to a Result containing either a tuple of the successful outputs or an error.

try_join! is similar to [join!], but completes immediately if any of the futures return an error.

This macro is only usable inside of async functions, closures, and blocks. It is also gated behind the async-await feature of this library, which is not activated by default.

Examples

When used on multiple futures that return Ok, try_join! will return Ok of a tuple of the values:

#![feature(async_await)]
use futures::{try_join, future};

let a = future::ready(Ok::<i32, i32>(1));
let b = future::ready(Ok::<u64, i32>(2));

assert_eq!(try_join!(a, b), Ok((1, 2)));

If one of the futures resolves to an error, try_join! will return that error:

#![feature(async_await)]
use futures::{try_join, future};

let a = future::ready(Ok::<i32, i32>(1));
let b = future::ready(Err::<u64, i32>(2));

assert_eq!(try_join!(a, b), Err(2));