Dart中的异步可迭代映射 [英] Asynchronous iterable mapping in Dart

问题描述

我可以使用异步映射功能映射一些Iterable吗？

Can I map some Iterable using async mapping function? Maybe it is a bug, that this code prints list of _Future imidiately, not ints after 1 or 5 seconds?

import 'dart:async';

Future<int> foo(int i) {
  var c = new Completer();
  new Timer(new Duration(seconds: 1), () => c.complete(i));
  return c.future;
}

main() {
  var list = [1,2,3,4,5];
  var mappedList = list.map((i) async => await foo(i));
  print(mappedList);
}

推荐答案

表达式（i）异步=> await foo（i）仍然返回一个将来。您可以使用 Future.wait（mappedList）等到所有创建的期货完成。

The expression (i) async => await foo(i) still returns a future. You can use Future.wait(mappedList) to wait till all created futures are completed.

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