Macro futures_util::try_join

macro_rules! try_join {
    #[proc_macro_hack(support_nested)] => { ... };
}

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 activated by default.

Examples

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

use futures::try_join;

let a = async { Ok::<i32, i32>(1) };
let b = async { 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:

use futures::try_join;

let a = async { Ok::<i32, i32>(1) };
let b = async { Err::<u64, i32>(2) };

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