小编Bru*_*You的帖子

好像Swift的Array不会经过didSet，为什么呢？

var intArray: [Int] = [] {
    didSet {
        intArray += [0]
    }
}

if intArray.count == 0 {
    println("Why is intArray not being altered?")
}

在 Dart 语言中，如何在保持生成值的同时在生成器函数中创建错误？

import 'dart:math' show Random;

main() {
  sum20RandomNumbers().then((sum) {
    print("Sum: $sum");
  });
}

Future<double> sum20RandomNumbers() async {
  var randomStream = generateRandomNumbers().handleError((error) {
    print('Ignore large number: ${error}');
    // How can I ignore error here?
  });

  int count = 0;
  double sum = 0;
  await for (var n in randomStream) {
    print(n);
    sum += n;
    if (++count >= 20) // sum 20 numbers at most
      break;
  }
  return sum;
}

Stream<double> generateRandomNumbers([int seed]) async* {
  final random = Random(seed);
  while …