ts的面向对象，用接口实现类后怎么统一调用？

上代码

type mapType = string

interface ILayer {
  readonly type: "pointIcon" | "point" | "pointSpiIcon"
}

interface IDrawConstructor {
  map: mapType
  layer: ILayer
  addPoint: (map: mapType, layer: ILayer) => void
}

interface IDrawPointConstructor {
  map: mapType
  layer: ILayer
}

// 实现接口
class DrawIconPoint implements IDrawConstructor {
  public layer: ILayer;
  public map: mapType;

  constructor(map: mapType, layer: ILayer) {
    super()
    this.map = map
    this.layer = layer
  }

  addPoint(map: mapType, layer: ILayer): void {
    console.log('iconPoint')
  }
}

// 实现接口
class DrawSpiritIconPoint implements IDrawConstructor {
  public layer: ILayer;
  public map: mapType;

  constructor(map: mapType, layer: ILayer) {
    super()
    this.map = map
    this.layer = layer
  }

  addPoint(map: mapType, layer: ILayer): void {
       console.log('iconSpiritPoint')
  }
}


// 导出统一类
export class DrawPoint implements IDrawPointConstructor {
  public map: mapType
  public layer: ILayer

  constructor(map: mapType, layer: ILayer) {
    this.map = map
    this.layer = layer
    layer.type === 'pointIcon' ?
      new DrawIconPoint(map, layer) : new DrawSpiritIconPoint(map, layer)
  }
}

现在想的是 只用 new 一个类 DrawPoint，然后传入参数，就能自动执行里面的实现类

现在是通过 if 判断来实现，考虑到后续会有 if 判断的条件增加，要手动来这里修改if的条件，有没有什么更好的实现方式