returning futures

Future<void> main() async {
  printCountdown();
  print("${await delayedGreeting()}");
}

Future<String> delayedGreeting() {
  return Future.delayed(Duration(seconds: 10), () => "Thank you for waiting 10 seconds");
}

void printCountdown() {
  for (int i = 1; i <= 10; i++) {
    Future.delayed(Duration(seconds: i), () {
      print(i);
    });
  }
}

Above code was inspired by what I read in flutter documentation. But I found this part most interesting:

Here, printCountdown enters 10 Future entries to the event loop, each setting of at different seconds (1, 2, 3, 4 ... 10). You could think the entry of these Futures as instantaneous. This is one way to use Future.delayed. But another one is in delayedGreeting. Notably, here we are able to return the result of the function passed to Future.delayed as if it came from delayedGreeting. Note that delayedGreeting returns the Future.delayed as it is.

returning futures

Comments