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.

Examples

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

#![feature(async_await, await_macro, futures_api)]
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, await_macro, futures_api)]
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));