Mixins

main.dart

void main() {
  final dev = Developer();
  dev.speak();
  
  final mgr = Manager();
  mgr.speak();
}

abstract class Person {
  String get saying;
  
  void speak();
}

mixin LoudSpeak implements Person {
  void speak() {
    print(saying.toUpperCase());
  }
}

class Developer with LoudSpeak implements Person {
  final String saying = 'foo';
}

class Manager with LoudSpeak implements Person {
  final String saying = 'testi';
}