trait ErrorDetector
{
public function onError(Promisable $promised)
{
printf("Oh noes: %s\n", (string) $promised->getError());
}
}
class AddTwo extends Thenable
{
use ErrorDetector;
public function onFulfilled(Promisable $promised)
{
$promised->meaning += 2;
/* throwing an exception here will cause invocation of
PrintMeaning::onError */
}
}
class PrintMeaning extends Thenable
{
use ErrorDetector;
public function onFulfilled(Promisable $promised)
{
printf("The meaning of life + 2: %d\n", $promised->meaning);
/* You can access exceptions thrown here using $promised->getError */
}
}
$manager = new PromiseManager();
$promise = new Promise($manager, new CalculateTheMeaningOfLife());
$promise->then(new AddTwo($promise))->then(new PrintMeaning($promise));
$manager->shutdown();
}
