Mixins - Dart Programming

mixin declares a reusable block of methods that no class instantiates on its own. A class composes mixins with class C with M1, M2, gaining their methods as if it had declared them. Mixins add behavior, not stored state.

Program

Play the program to call a method that chains through two composed mixins.

mixins.dart

mixin Greetable {
  String greet(String name) => 'Hello, $name';
}

mixin Loud {
  String shout(String msg) => '${msg.toUpperCase()}!';
}

class Bot with Greetable, Loud {
  String announce(String name) => shout(greet(name));
}

void main() {
  var b = Bot();
  print(b.announce('Ada'));
}

mixin `mixin Greetable { ... }` declares reusable methods; a mixin cannot be instantiated on its own.

with `class Bot with Greetable, Loud` composes both mixins so their methods belong to `Bot`.

composition over inheritance Mixins add behavior without sharing state or forcing a single inheritance chain.