Add methods or values to enum in dart

In java when you are defining an enum you can do something similar to the following. Is this possible in Dart?

enum blah {
  one(1), two(2);
  final num value;
  blah(this.value);
}

Starting with Dart 2.6 you can define extensions on classes (Enums included).

enum Cat {
  black,
  white
}

extension CatExtension on Cat {

  String get name {
    switch (this) {
      case Cat.black:
        return 'Mr Black Cat';
      case Cat.white:
        return 'Ms White Cat';
      default:
        return null;
    }
  }

  void talk() {
    print('meow');
  }
}

Example:

Cat cat = Cat.black;
String catName = cat.name;
cat.talk();

Here's one more live example (uses a constant map instead of a switch): https://dartpad.dartlang.org/c4001d907d6a420cafb2bc2c2507f72c

Dart enums are used only for the simplest cases. If you need more powerful or more flexible enums, use classes with static const fields like shown in https://stackoverflow.com/a/15854550/217408

This way you can add whatever you need.

Nope. In Dart, enums can only contain the enumerated items:

enum Color {
  red,
  green,
  blue
}

However, each item in the enum automatically has an index number associated with it:

print(Color.red.index);    // 0
print(Color.green.index);  // 1

You can get the values by their index numbers:

print(Color.values[0] == Color.red);  // True

See: https://www.dartlang.org/guides/language/language-tour#enums

Add methods or values to enum in dart

Related

Recent Posts