How to use a single Promise in v3?

[Pader]

Just a simple example:

<?php

use function Amp\async;
use function Amp\delay;

require __DIR__.'/vendor/autoload.php';

async('Amp\delay', 3000)->onResolve(function() {
    print("After delay 3000\n");
});

This code has no any output..

async('Amp\delay', 3000)->onResolve(function() {
    print("After delay 3000\n");
});

delay(2000);
echo "After delay 2000\n";

This has 2000 and 3000 delay output.

async('Amp\delay', 3000)->onResolve(function() {
    print("After delay 3000\n");
});

Loop::getDriver()->run();

This has output.

The question is how to use a simple Promise with callback? Not coroutine synchronous writing

[Niklas Keller]

There won't be callbacks in v3. Either you await or you need to use run() as you did.

[Pader]

That's weird, Fiber support writing code as synchronous, but look's like force to use synchronous style, sometimes let concurrent programming become difficult, sometimes we need callback, this makes many callback style invalid.

[Niklas Keller]

Where do you need promise callbacks? You can always start a new fiber and invoke your callback there.

[Pader]

See my other issue: #352
I can't make amp v3 compatible with traditional asynchronous framework because they use callback.
The synchronous code block whole stack.
I think may be the question is Event-Loop.

[Pader]

After some learning, I found that the best way is still async() and driver->run(), I now have a different understanding.