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(还有??).至少在语言功能出现之前，构建枚举的正确或惯用方法是什么?

解决方案

随着 r41815 Dart 得到了原生的 Enum 支持，参见 http://dartbug.com/21416 并且可以像

一样使用

enum Status {没有任何，跑步，停了下来，暂停}无效主(){打印(状态.值)；Status.values.forEach((v) => print('value: $v, index: ${v.index}'));打印('运行:${Status.running}，${Status.running.index}')；print('运行索引:${Status.values[1]}');}

<块引用>

[Status.none、Status.running、Status.stopped、Status.paused]
值:Status.none，索引:0
值:Status.running，索引:1
值:Status.stopped，索引:2
值:Status.paused，索引:3
正在运行:Status.running, 1
运行索引:Status.running

一个限制是不可能为枚举项设置自定义值，它们会自动编号.

该草案中的更多详细信息 https://www.dartlang.org/docs/规范/EnumsTC52draft.pdf

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?

解决方案

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

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

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

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