Mixins trong Dart

mixin Swimming {
  void swim() {
    print('Swimming...');
  }
}
 
mixin Flying {
  void fly() {
    print('Flying...');
  }
}
 
class Duck with Swimming, Flying {
  String name;
  Duck(this.name);
}
 
void main() {
  var duck = Duck('Donald');
  duck.swim();  // Swimming...
  duck.fly();   // Flying...
}

mixin Counter {
  int _count = 0;
  
  int get count => _count;
  
  void increment() => _count++;
  void decrement() => _count--;
  void reset() => _count = 0;
}
 
class ClickCounter with Counter {
  String label;
  ClickCounter(this.label);
}
 
void main() {
  var counter = ClickCounter('Clicks');
  counter.increment();
  counter.increment();
  print('${counter.label}: ${counter.count}');
}

class Animal {
  String name;
  Animal(this.name);
}
 
mixin Swimmer {
  void swim() => print('Swimming');
}
 
mixin Runner {
  void run() => print('Running');
}
 
class Dog extends Animal with Runner {
  Dog(String name) : super(name);
}
 
class Fish extends Animal with Swimmer {
  Fish(String name) : super(name);
}

class Performer {
  void perform() => print('Performing');
}
 
mixin Musical on Performer {
  void playMusic() {
    perform();  // Có thể gọi method từ Performer
    print('Playing music');
  }
}
 
class Musician extends Performer with Musical {}
 
void main() {
  var musician = Musician();
  musician.playMusic();
}

mixin A {
  String greet() => 'A';
}
 
mixin B {
  String greet() => 'B';
}
 
class TestAB with A, B {}
class TestBA with B, A {}
 
void main() {
  print(TestAB().greet());  // B (cuối cùng thắng)
  print(TestBA().greet());  // A
}

mixin Loggable {
  void log(String message) {
    print('[${DateTime.now()}] $message');
  }
}
 
mixin Validatable {
  bool validate() => true;
}
 
class UserService with Loggable, Validatable {
  void createUser(String name) {
    log('Creating user: $name');
    if (validate()) {
      log('User created successfully');
    }
  }
}

mixin class Describable {
  String describe() => 'Describable object';
}
 
// Có thể dùng như mixin
class Product with Describable {}
 
// Hoặc như class thường
class Item extends Describable {}