flutter：仅使用“元素”卸载“元素”时收到通知

Question

我目前正在为自己的目的直接处理Element 。 我当前的环境不允许我使用State 。 我想知道是否直接使用Element卸载了小部件或元素。 我目前的解决方法是

try {
  /// If the element is `unmounted`, this will throw with the null safety
  if (element.widget == null) {
    print("Element is not mounted at this time");
  } else {
    print("Widget is still mounted");
  }
} catch (e) {
  print("Element is not mounted at this time");
}

如果我想在卸载元素时收到通知：

void notifiedWhenUnmounted() {
  WidgetsBinding.instance.addPostFrameCallback(() {
    try {
      /// If the element is `unmounted`, this will throw with the null safety
      if (element.widget == null) {
        return print("Element is not mounted at this time");
      } 
      print("Widget is still mounted");
      notifiedWhenUnmounted(); // add post frame callback again. 
    } catch (e) {
      print("Element is not mounted at this time");
    }
  });
}

仅使用BuildContext或Element有更好的方法吗？