Fullfilled or Rejected promise and then method about promise HOT 9 CLOSED

Promise resolution is synchronous by default, except when you resolve them asynchronously.

$loop->futureTick(function () use ($d) {
    $d->resolve('resolve');
});

from promise.

I think that then method must be asynchronous.

I think it fix all problem here.

I found another implementation of promise in popular framework mojolicious (sorry this is perl but code implementation is very simple). The method then is called there asynchronously. Link to code.

What do you think about it?

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Could you explain why resolution should be asynchronous and what exact problem would be solved?

from promise.

I write tests where i use run and stop method of event loop many times.
Simplified code of my tests looks like it is written in the first post.
Then method should be non-blocking because of expected behavior.

from promise.

Bear in mind that a promise is nothing more then a communication channel. It only does things when you it to. So while it's own execution is synchronous it enables us to write non-blocking code. The then does nothing more then set the callbacks to run when the promise resolves, and run it when the promise already resolved. Consider the following:

$deferred = new Deferred();

We get a promise from the deferred object and set a resolve handler on it:

$deferred->promise()->then(function () {
    echo 'resolved!', PHP_EOL;
});

Now up to this point nothing is echoed. But once we call $deferred->resolve(); resolved! will be echoed. So when you call it like this resolved! will be echoed the moment you call then:

$deferred = new Deferred();
$deferred->resolve();
$deferred->promise()->then(function () {
    echo 'resolved!', PHP_EOL;
});

And that is exactly what your example does, it resolves the promise the moment you create it. Which is the expected behaviour.

Also the reason why you have an infinite loop with that example is because you have an open connection with Google and it takes a while for the timeout to kick in and the connection to close.

from promise.

Also the reason why you have an infinite loop with that example is because you have an open connection with Google and it takes a while for the timeout to kick in and the connection to close.

I repeat, I am writing tests. The connection is established in the setup method, and the connection is closed in the teardown method. This is logical for me. The effect is the same.

And that is exactly what your example does, it resolves the promise the moment you create it. Which is the expected behaviour.

It looks like for different people the expected behavior is different. For this reason, I am going to close the topic.

I have a question, how to use assert in event loop or what if exception appears in event loop in tests? At this point, there is an infinite loop again.

from promise.

@Logioniz these tests? https://github.com/Logioniz/reactphp-memcached/blob/master/tests/FunctionalTest.php#L242

from promise.

Yes.

from promise.

Cheers, slowly working on a PR with some suggestions 😄

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