如何使用Dart构建枚举？ [英] How can I build an enum with Dart?

问题描述

Dart语言没有枚举（但是）。

The Dart language does not have enums (yet??). What is the proper or idiomatic way to construct an enum, at least until a language feature arrives?

推荐答案

使用r41815 Dart得到了原生的枚举支持请参见 http://dartbug.com/21416 ，并可以使用

With r41815 Dart got native Enum support see http://dartbug.com/21416 and can be used like

enum Status {
  none,
  running,
  stopped,
  paused
}

void main() {
  print(Status.values);
  Status.values.forEach((v) => print('value: $v, index: ${v.index}'));
  print('running: ${Status.running}, ${Status.running.index}');
  print('running index: ${Status.values[1]}');
}

[Status.none，Status.running， Status.stopped，Status.paused]

value：Status.none，index：0

value：Status.running，index：1

value：Status .stopped，index：2

value：Status.paused，index：3

running：Status.running，1

running index：Status.running

[Status.none, Status.running, Status.stopped, Status.paused]
value: Status.none, index: 0
value: Status.running, index: 1
value: Status.stopped, index: 2
value: Status.paused, index: 3
running: Status.running, 1
running index: Status.running

限制是不能为枚举项设置自定义值，它们会自动编号。

A limitation is that it is not possibly to set custom values for an enum item, they are automatically numbered.

本草案中的更多详情，请参阅 https：// www。 dartlang.org/docs/spec/EnumsTC52draft.pdf

More details at in this draft https://www.dartlang.org/docs/spec/EnumsTC52draft.pdf

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