如何在Dart/Flutter中扩展类

// 定义一个Mixin
mixin Flyable {
  void fly() {
    print('Flying...');
  }
}

// 定义一个基类
class Animal {
  void eat() {
    print('Eating...');
  }
}

// 使用Mixin扩展基类
class Bird extends Animal with Flyable {}

void main() {
  var bird = Bird();
  bird.eat(); // 输出: Eating...
  bird.fly(); // 输出: Flying...
}

// 定义一个基类
class Person {
  String name;
  int age;

  Person(this.name, this.age);
}

// 使用Extension为Person类添加新方法
extension PersonExtensions on Person {
  void greet() {
    print('Hello, my name is $name and I am $age years old.');
  }
}

void main() {
  var person = Person('Alice', 30);
  person.greet(); // 输出: Hello, my name is Alice and I am 30 years old.
}