dispose method

@override void dispose()

Mark the notifier as disposed and release resources.

标记通知器为已释放并释放相关资源。

Implementation

@override
void dispose() {
  if (!_isDisposed) {
    _isDisposed = true;
    super.dispose();
  } else {
    logw("Attempted to dispose an already disposed notifier.", tag: _tag);
  }
}