import 'package:flutter/material.dart'; class PublishNotifier extends ChangeNotifier { T? _value; set value(T newValue) { if (_value != newValue) { _value = newValue; notifyListeners(); } } T? get currentValue => _value; void addPublishListener(void Function(T) callback) { super.addListener( () { if (_value != null) { callback(_value!); } }, ); } }