HarmonyOS 如何把当前组件的this变为全局变量

示例参考如下：

Child.ets

@Component
export struct Child {
  @State private text: string = '初始值';
  private controller: ChildController = new ChildController();

  test() {
    console.info('test')
  }

  aboutToAppear() {
    if (this.controller) {
      //给controller对应的方法赋值
      this.controller.changeText = this.changeText;
    }
  }

  private changeText = (value: string) => {
    this.text = value;
    this.test()
  }

  build() {
    Column() {
      Text(this.text)
    }
  }
}

//定义controller对象
export class ChildController {
  changeText = (value: string) => {
  }
}

Index.ets

import { Child, ChildController } from './Child';

@Entry
@Component
struct Parent {
  private ChildRef = new ChildController();

  build() {
    Column() {
      Text('调用Child的changeText').fontSize('18vp').fontColor(Color.Gray)
      Divider()
      Child({ controller: this.ChildRef })
      Button('Parent调用child的changeText').onClick(() => {
        this.ChildRef.changeText('Parent调用child的changeText');
      })
    }
    .justifyContent(FlexAlign.Center)
    .width('100%')
    .height('100%')
  }
}