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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