HarmonyOS 怎么自定义装饰器

ArkTS支持TS5.0之前的TS装饰器语法。关于装饰器的定义和运行时行为，可以参考TS官方文档：https://www.typescriptlang.org/docs/handbook/decorators.html。

注意，如果在ets文件中定义装饰器，则需要同时满足ArkTS的语法规则，比如不能使用any等。以下是简单示例：

// 类装饰器
function decorateKlass(target: ESObject) {
  console.log("decorateKlass")
}

@decorateKlass
class Person {
  age: number = 12
}


// 方法装饰器
export function MyDescriptor(target: Object, key: string, descriptor: PropertyDescriptor) {
  const originalMethod: Function = descriptor.value
  descriptor.value = (...args: Object[]) => {
    console.log(`Calling ${target.constructor.name} method ${key} with argument: ${args}`)
    const result: Object = originalMethod(...args)
    console.log(`Method ${key} returned: ${result}`)
    return result
  }
  return descriptor
}

@Entry
@Component
struct DecoratorDemo {
  @State message: string = 'Hello World';

  aboutToAppear() {
    this.demo()
  }

  build() {
    Flex() {
    }
    .backgroundColor(Color.Green)
    .constraintSize({
      minWidth: 100,
      maxWidth: 200,
      minHeight: 0,
      maxHeight: 200
    })
    .height('100%')
  }

  @MyDescriptor
  demo() {
    let person = new Person();
    return person.age
  }
}