Does Dart support enumerations?
Beginning 1.8, you can use enums like this:
enum Fruit {
apple, banana
}
main() {
var a = Fruit.apple;
switch (a) {
case Fruit.apple:
print('it is an apple');
break;
}
// get all the values of the enums
for (List<Fruit> value in Fruit.values) {
print(value);
}
// get the second value
print(Fruit.values[1]);
}
The old approach before 1.8:
class Fruit {
static const APPLE = const Fruit._(0);
static const BANANA = const Fruit._(1);
static get values => [APPLE, BANANA];
final int value;
const Fruit._(this.value);
}
Those static constants within the class are compile time constants, and this class can now be used in, for example, switch
statements:
var a = Fruit.APPLE;
switch (a) {
case Fruit.APPLE:
print('Yes!');
break;
}
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