如何在运行时实现Angular中的多态性？

// Step 1: 创建父类
class Shape {
  constructor(public name: string) {}

  // 共有方法
  calculateArea(): number {
    return 0;
  }
}

// Step 2: 创建子类
class Circle extends Shape {
  constructor(public name: string, public radius: number) {
    super(name);
  }

  // 重写父类方法
  calculateArea(): number {
    return Math.PI * this.radius * this.radius;
  }
}

class Rectangle extends Shape {
  constructor(public name: string, public width: number, public height: number) {
    super(name);
  }

  // 重写父类方法
  calculateArea(): number {
    return this.width * this.height;
  }
}

// Step 3: 使用多态性
const shapes: Shape[] = [
  new Circle("圆形", 5),
  new Rectangle("矩形", 3, 4)
];

shapes.forEach(shape => {
  console.log(`图形名称：${shape.name}`);
  console.log(`图形面积：${shape.calculateArea()}`);
});