HarmonyOS 鸿蒙Next 状态管理之ObjectLink的疑惑

只在使用状态变量的组件会重新渲染，可以参考下面demo

class BasicDataSource implements IDataSource {
 private listeners: DataChangeListener[] = [];
 private originDataArray: StringData[] = [];
 public totalCount(): number {
   return 0;
 }

 public getData(index: number): StringData {
   return this.originDataArray[index];
 }

 registerDataChangeListener(listener: DataChangeListener): void {
   if (this.listeners.indexOf(listener) < 0) {
     console.info('add listener');
     this.listeners.push(listener);
   }
 }

 unregisterDataChangeListener(listener: DataChangeListener): void {
   const pos = this.listeners.indexOf(listener);
   if (pos >= 0) {
     console.info('remove listener');
     this.listeners.splice(pos, 1);
   }
 }

 notifyDataReload(): void {
   this.listeners.forEach(listener => {
     listener.onDataReloaded();
   })
 }

 notifyDataAdd(index: number): void {
   this.listeners.forEach(listener => {
     listener.onDataAdd(index);
   })
 }

 notifyDataChange(index: number): void {
   this.listeners.forEach(listener => {
     listener.onDataChange(index);
   })
 }

 notifyDataDelete(index: number): void {
   this.listeners.forEach(listener => {
     listener.onDataDelete(index);
   })
 }

 notifyDataMove(from: number, to: number): void {
   this.listeners.forEach(listener => {
     listener.onDataMove(from, to);
   })
 }
}

class MyDataSource extends BasicDataSource {
 private dataArray: StringData[] = [];
 public totalCount(): number {
   return this.dataArray.length;
 }

 public getData(index: number): StringData {
   return this.dataArray[index];
 }

 public addData(index: number, data: StringData): void {
   this.dataArray.splice(index, 0, data);
   this.notifyDataAdd(index);
 }

 public pushData(data: StringData): void {
   this.dataArray.push(data);
   this.notifyDataAdd(this.dataArray.length - 1);
 }
}

[@Observed](/user/Observed)
class StringData {
 message: string;
 constructor(message: string) {
   this.message = message;
 }
}

[@Entry](/user/Entry)
[@Component](/user/Component)
struct MyComponent {
 private moved: number[] = [];
 [@State](/user/State) data: MyDataSource = new MyDataSource();
 
 aboutToAppear() {
   for (let i = 0; i <= 20; i++) {
     this.data.pushData(new StringData(`Hello ${i}`));
   }
 }

 build() {
   List({ space: 3 }) {
     LazyForEach(this.data, (item: StringData, index: number) => {
       ListItem() {
         Row() {
           ChildComponent({ data: item })
           Text(item.message)
         }
       }
       .onClick(() => {
         item.message += '0';
       })
     }, (item: StringData, index: number) => index.toString())
   }.cachedCount(5)
 }
}

[@Component](/user/Component)
struct ChildComponent {
 [@ObjectLink](/user/ObjectLink) [@Watch](/user/Watch)('change') data: StringData

 change() {
   this.dd = this.data.message
   this.ccc = this.data.message
 }

 [@State](/user/State) dd: string = 'sssss'
 private ccc: string = 'sssss'

 build() {
   Row() {
     Text(this.dd)
     Text(this.ccc)
     Text(this.data.message).fontSize(50)
       .onAppear(() => {
         console.info("appear:" + this.data.message)
       })
   }.margin({ left: 10, right: 10 })
 }
}