Future::failed

(PHP 8.6+, True Async 1.0)

public static function failed(\Throwable $throwable): Future

Creates a Future that is immediately completed with the specified error. Calling await() on such a Future will throw the provided exception.

Parameters

throwable — the exception with which the Future will be completed.

Return value

Future — a completed Future with an error.

Examples

Example #1 Creating a Future with an error

<?php

use Async\Future;

$future = Future::failed(new \RuntimeException("Loading error"));

var_dump($future->isCompleted()); // bool(true)

try {
    $future->await();
} catch (\RuntimeException $e) {
    echo "Caught: " . $e->getMessage() . "\n";
    // Caught: Loading error
}

Example #2 Using for early error return

<?php

use Async\Future;

function connectToService(string $host): Future {
    if (empty($host)) {
        return Future::failed(
            new \InvalidArgumentException("Host cannot be empty")
        );
    }

    return \Async\async(function() use ($host) {
        return performConnection($host);
    });
}

$future = connectToService('');
$future->catch(function(\Throwable $e) {
    echo "Error: " . $e->getMessage() . "\n";
});

Documentation