Debug data for promises

[EligiusSantori]

Please add something to help debugging the code written via promises. Closues-based code makes stacktrace useless, and without stacktrace debugging some mostly working remote code is barely possible. On Node.js there is whole layer of knowledge exists to cope with it. I think I also saw there custom promises implementation which solve it in some way.

[EligiusSantori]

I guess simplest way to do it is using PHP 8 attributes. Then code may look like:

$client = new React\Http\Browser();

$client->get('http://www.google.com/')->then(#[StepName('handle-response')] function (Psr\Http\Message\ResponseInterface $response) {
    throw new \Exception('Dummy exception.');
})->catch(function (\Throwable $reason, ?string $stepName) {
    file_put_contents(STDERR, "Exception: ".$reason->getMessage()." in step ".$stepName);
});

Or in more general way:

$client = new React\Http\Browser();

$client->get('http://www.google.com/')->then(#[StepName('handle-response')] function (Psr\Http\Message\ResponseInterface $response) {
    throw new \Exception('Dummy exception.');
})->catch(function (\Throwable $reason, ?Closure $fn) {
    //...
});

[SimonFrings]

Hey @EligiusSantori, I can understand that this makes working with promises, especially when it comes to debugging, somewhat more complex. This is one of the reasons why we released v4 of our reactphp/asnyc package, so you can simply use async() and await() on PHP 8.1+ without caring too much about promises. If you're using a PHP version below 8.1, you can also use coroutines, which work in a similar way. Additionally, the more we approach the future of ReactPHP (ReactPHP v3 & v4), the less you have to deal with promises in general.

With this all said, I think it would make more sense to invest the time to move towards a ReactPHP v3/v4, as promises will move more and more into the background.

Thanks for bringing in your idea, hope this gives some insights into our plans for ReactPHP and helps you proceed :)

[EligiusSantori]

Hello, @SimonFrings. Thanks for your response, I'll try async/await approach in the next few days and will report here is it solves the problem. As I read before, JavaScript has async/await support in it's core and it also has some improvements in exceptions handling related to async/await, so I didn't expect much from library-level implementation. I'll follow your recommendation, but I need some time to try it and give a thoughtful answer.

[EligiusSantori]

UPD: I tried async/await and it works good enough both for user-code exceptions and deep nested exceptions in promise-using libraries. The problem can be considered solved. Thanks again.