Basic examples of ways to utilize async functions in Dart

readme.md

Basic Examples: Using async functions

Basic examples of ways to utilize async functions in Dart

Find this at dartpad.dartlang.org/716d6f8fc2edc604e671e513e2690efe.

main.dart

import 'dart:async';
import 'dart:math' as math;

var rnd = new math.Random();

///Asynchronous method that returns back a random int
Future<int> getNumber(num max) {
  return new Future.delayed(new Duration(seconds: rnd.nextInt(3)), () => rnd.nextInt(max));
}

///Asynchronous method to flip a coin (without await)
Future<bool> isHeads() {
  return getNumber(2).then( (int n) {
    return n.isEven;
  });
}

///Asynchronous method to flip a coin (with wait)
Future<bool> isTails() async {
  int n = await getNumber(2);
  return n.isOdd;
}

///Asynchronous method to flip multiple coins (with Future.wait())
Future<num> flipN(int n) {
  List<Future> flips = new List<Future>();
  for (int i = 0; i < n; i++) {
    flips.add(isHeads().whenComplete(() => print(" (flip completed)")));
  }
  return Future.wait(flips).then((List results) {
    return results.where((f) => f).length / results.length;
  });  
}

main() {
  for (int i = 0; i < 10; i++) {
    isHeads().then( (f) => print ("Is Heads?: $f"));
    isTails().then( (f) => print ("Is Tails?: $f"));
  }

  int numFlips = 10;
  flipN(numFlips).then( (ratio) => print("${numFlips} flips completed with ${ratio} heads"));
}