/**
* Invokes the specified function asynchronously on the specified scheduler, surfacing the result through an
* observable sequence.
*
* @param callable $action
* @param SchedulerInterface $scheduler
* @return AnonymousObservable
*
* @demo start/start.php
* @operator
* @reactivex start
*/
public static function start(callable $action, SchedulerInterface $scheduler = null)
{
$scheduler = $scheduler ?: new ImmediateScheduler();
$subject = new AsyncSubject();
$scheduler->schedule(function () use($subject, $action) {
$result = null;
try {
$result = call_user_func($action);
} catch (\Exception $e) {
$subject->onError($e);
return;
}
$subject->onNext($result);
$subject->onCompleted();
});
return $subject->asObservable();
}
