使用Typesciprt通过继承公开Angular2中的公共函数

Question

假设我有一个扩展CommonComponent的HealthBar组件，我想访问baseComponent中的公共事件服务。

export class CommonComponent { 

constructor(private eventService:EventService){}

/*
broadcast (eventName, eventObj){
    let broadcastStr = this.name + " broadcast " + eventName;
    this.log(broadcastStr, eventObj)
    this.eventService.broadcast(eventName, eventObj );
}
*/

public broadcast = function(eventName, eventObj){
    this.eventService.broadcast(eventName, eventObj );
}

healthBar可以访问旧的＆＃34; public broadcast = function＆＃34;但不是新注释掉的broadcast（）语法。我以为他们是一回事，不是吗？为什么广告（）不公开给儿童组件？