improve framework structure, added StateMixin, prepare to getx 4.0

@@ -3,43 +3,22 @@ import 'package:get/get.dart';
 import '../../domain/adapters/repository_adapter.dart';
 import '../../domain/adapters/repository_adapter.dart';
 import '../../domain/entity/cases_model.dart';
 import '../../domain/entity/cases_model.dart';
 
 
-enum Status { loading, success, error }
-
-class HomeController extends GetxController {
+class HomeController extends GetxController with StatusMixin<CasesModel> {
   HomeController({this.homeRepository});
   HomeController({this.homeRepository});
 
 
   /// inject repo abstraction dependency
   /// inject repo abstraction dependency
   final IHomeRepository homeRepository;
   final IHomeRepository homeRepository;
 
 
-  /// create a reactive status from request with initial value = loading
-  final status = Status.loading.obs;
-
-  /// create a reactive CasesModel. CasesModel().obs has same result
-  final cases = Rx<CasesModel>();
-
   /// When the controller is initialized, make the http request
   /// When the controller is initialized, make the http request
   @override
   @override
   void onInit() {
   void onInit() {
     super.onInit();
     super.onInit();
-    fetchDataFromApi();
-  }
-
-  /// fetch cases from Api
-  Future<void> fetchDataFromApi() async {
-    /// When the repository returns the value, change the status to success,
-    /// and fill in "cases"
-    return homeRepository.getCases().then(
-      (data) {
-        cases(data);
-        status(Status.success);
-      },
-
-      /// In case of error, print the error and change the status
-      /// to Status.error
-      onError: (err) {
-        print("$err");
-        return status(Status.error);
-      },
-    );
+    // show loading on start, data on success
+    // and error message on error with 0 boilerplate
+    homeRepository.getCases().then((data) {
+      change(data, status: RxStatus.success());
+    }, onError: (err) {
+      change(null, status: RxStatus.error(err.toString()));
+    });
   }
   }
 }
 }

@@ -29,9 +29,9 @@ class CountryView extends GetView<HomeController> {
             ),
             ),
             body: Center(
             body: Center(
               child: ListView.builder(
               child: ListView.builder(
-                  itemCount: controller.cases.value.countries.length,
+                  itemCount: controller.value.countries.length,
                   itemBuilder: (context, index) {
                   itemBuilder: (context, index) {
-                    final country = controller.cases.value.countries[index];
+                    final country = controller.value.countries[index];
                     return ListTile(
                     return ListTile(
                       onTap: () {
                       onTap: () {
                         Get.toNamed('/details', arguments: country);
                         Get.toNamed('/details', arguments: country);

@@ -27,11 +27,8 @@ class HomeView extends GetView<HomeController> {
           centerTitle: true,
           centerTitle: true,
         ),
         ),
         body: Center(
         body: Center(
-          child: Obx(
-            () {
-              final status = controller.status.value;
-              if (status == Status.loading) return CircularProgressIndicator();
-              if (status == Status.error) return Text('Error on connection :(');
+          child: controller(
+            (state) {
               return Column(
               return Column(
                 mainAxisAlignment: MainAxisAlignment.center,
                 mainAxisAlignment: MainAxisAlignment.center,
                 children: [
                 children: [
@@ -45,7 +42,7 @@ class HomeView extends GetView<HomeController> {
                     ),
                     ),
                   ),
                   ),
                   Text(
                   Text(
-                    '${controller.cases.value.global.totalConfirmed}',
+                    '${state.global.totalConfirmed}',
                     style: TextStyle(fontSize: 45, fontWeight: FontWeight.bold),
                     style: TextStyle(fontSize: 45, fontWeight: FontWeight.bold),
                   ),
                   ),
                   SizedBox(
                   SizedBox(
@@ -58,7 +55,7 @@ class HomeView extends GetView<HomeController> {
                     ),
                     ),
                   ),
                   ),
                   Text(
                   Text(
-                    '${controller.cases.value.global.totalDeaths}',
+                    '${state.global.totalDeaths}',
                     style: TextStyle(fontSize: 45, fontWeight: FontWeight.bold),
                     style: TextStyle(fontSize: 45, fontWeight: FontWeight.bold),
                   ),
                   ),
                   SizedBox(
                   SizedBox(

@@ -59,18 +59,18 @@ void main() {
     expect(controller.initialized, true);
     expect(controller.initialized, true);
 
 
     /// check initial Status
     /// check initial Status
-    expect(controller.status.value, Status.loading);
+    expect(controller.status.isLoading, true);
 
 
     /// await time request
     /// await time request
     await Future.delayed(Duration(milliseconds: 100));
     await Future.delayed(Duration(milliseconds: 100));
 
 
-    if (controller.status.value == Status.error) {
-      expect(controller.cases.value, null);
+    if (controller.status.isError) {
+      expect(controller.value, null);
     }
     }
 
 
-    if (controller.status.value == Status.success) {
-      expect(controller.cases.value.global.totalDeaths, 100);
-      expect(controller.cases.value.global.totalConfirmed, 200);
+    if (controller.status.isSuccess) {
+      expect(controller.value.global.totalDeaths, 100);
+      expect(controller.value.global.totalConfirmed, 200);
     }
     }
   });
   });
 
 

-import 'package:meta/meta.dart';
 import '../../get_core/get_core.dart';
 import '../../get_core/get_core.dart';
 
 
 /// Special callable class to keep the contract of a regular method, and avoid
 /// Special callable class to keep the contract of a regular method, and avoid
@@ -18,37 +17,34 @@ class _InternalFinalCallback<T> {
 /// ```dart
 /// ```dart
 /// class SomeController with GetLifeCycle {
 /// class SomeController with GetLifeCycle {
 ///   SomeController() {
 ///   SomeController() {
-///     initLifeCycle();
+///     configureLifeCycle();
 ///   }
 ///   }
 /// }
 /// }
 /// ```
 /// ```
-mixin GetLifeCycle {
-  /// The `initLifeCycle` works as a constructor for the [GetLifeCycle]
-  ///
-  /// This method must be invoked in the constructor of the implementation
-  void initLifeCycle() {
-    onStart._callback = _onStart;
-    onDelete._callback = _onDelete;
-  }
-
+mixin GetLifeCycleBase {
   /// Called at the exact moment the widget is allocated in memory.
   /// Called at the exact moment the widget is allocated in memory.
   /// It uses an internal "callable" type, to avoid any @overrides in subclases.
   /// It uses an internal "callable" type, to avoid any @overrides in subclases.
   /// This method should be internal and is required to define the
   /// This method should be internal and is required to define the
   /// lifetime cycle of the subclass.
   /// lifetime cycle of the subclass.
   final onStart = _InternalFinalCallback<void>();
   final onStart = _InternalFinalCallback<void>();
 
 
+  // /// The `configureLifeCycle` works as a constructor for the [GetLifeCycle]
+  // ///
+  // /// This method must be invoked in the constructor of the implementation
+  // void configureLifeCycle() {
+  //   if (_initialized) return;
+  // }
+
   /// Internal callback that starts the cycle of this controller.
   /// Internal callback that starts the cycle of this controller.
   final onDelete = _InternalFinalCallback<void>();
   final onDelete = _InternalFinalCallback<void>();
 
 
   /// Called immediately after the widget is allocated in memory.
   /// Called immediately after the widget is allocated in memory.
   /// You might use this to initialize something for the controller.
   /// You might use this to initialize something for the controller.
-  @mustCallSuper
   void onInit() {}
   void onInit() {}
 
 
   /// Called 1 frame after onInit(). It is the perfect place to enter
   /// Called 1 frame after onInit(). It is the perfect place to enter
   /// navigation events, like snackbar, dialogs, or a new route, or
   /// navigation events, like snackbar, dialogs, or a new route, or
   /// async request.
   /// async request.
-  @mustCallSuper
   void onReady() {}
   void onReady() {}
 
 
   /// Called before [onDelete] method. [onClose] might be used to
   /// Called before [onDelete] method. [onClose] might be used to
@@ -57,7 +53,6 @@ mixin GetLifeCycle {
   /// Or dispose objects that can potentially create some memory leaks,
   /// Or dispose objects that can potentially create some memory leaks,
   /// like TextEditingControllers, AnimationControllers.
   /// like TextEditingControllers, AnimationControllers.
   /// Might be useful as well to persist some data on disk.
   /// Might be useful as well to persist some data on disk.
-  @mustCallSuper
   void onClose() {}
   void onClose() {}
 
 
   bool _initialized = false;
   bool _initialized = false;
@@ -83,6 +78,26 @@ mixin GetLifeCycle {
     _isClosed = true;
     _isClosed = true;
     onClose();
     onClose();
   }
   }
+
+  void $configureLifeCycle() {
+    _checkIfAlreadyConfigured();
+    onStart._callback = _onStart;
+    onDelete._callback = _onDelete;
+  }
+
+  void _checkIfAlreadyConfigured() {
+    if (_initialized) {
+      throw """You can only call configureLifeCycle once. 
+The proper place to insert it is in your class's constructor 
+that inherits GetLifeCycle.""";
+    }
+  }
+}
+
+abstract class GetLifeCycle with GetLifeCycleBase {
+  GetLifeCycle() {
+    $configureLifeCycle();
+  }
 }
 }
 
 
 /// Allow track difference between GetxServices and GetxControllers
 /// Allow track difference between GetxServices and GetxControllers

@@ -10,11 +10,7 @@ import '../../../get_instance/src/lifecycle.dart';
 /// it is Get.reset().
 /// it is Get.reset().
 abstract class GetxService extends DisposableInterface with GetxServiceMixin {}
 abstract class GetxService extends DisposableInterface with GetxServiceMixin {}
 
 
-abstract class DisposableInterface with GetLifeCycle {
-  DisposableInterface() {
-    initLifeCycle();
-  }
-
+abstract class DisposableInterface extends GetLifeCycle {
   /// Called immediately after the widget is allocated in memory.
   /// Called immediately after the widget is allocated in memory.
   /// You might use this to initialize something for the controller.
   /// You might use this to initialize something for the controller.
   @override
   @override
@@ -29,7 +25,9 @@ abstract class DisposableInterface with GetLifeCycle {
   /// async request.
   /// async request.
   @override
   @override
   @mustCallSuper
   @mustCallSuper
-  void onReady() {}
+  void onReady() {
+    super.onReady();
+  }
 
 
   /// Called before [onDelete] method. [onClose] might be used to
   /// Called before [onDelete] method. [onClose] might be used to
   /// dispose resources used by the controller. Like closing events,
   /// dispose resources used by the controller. Like closing events,
@@ -38,5 +36,7 @@ abstract class DisposableInterface with GetLifeCycle {
   /// like TextEditingControllers, AnimationControllers.
   /// like TextEditingControllers, AnimationControllers.
   /// Might be useful as well to persist some data on disk.
   /// Might be useful as well to persist some data on disk.
   @override
   @override
-  void onClose() {}
+  void onClose() {
+    super.onClose();
+  }
 }
 }

@@ -5,29 +5,77 @@ import '../../../instance_manager.dart';
 import '../../get_state_manager.dart';
 import '../../get_state_manager.dart';
 import '../simple/list_notifier.dart';
 import '../simple/list_notifier.dart';
 
 
-class Value<T> extends ListNotifier implements ValueListenable<T> {
-  Value(this._value);
+mixin StatusMixin<T> on ListNotifier {
+  T _value;
+  RxStatus _status;
+
+  bool _isNullOrEmpty(dynamic val) {
+    if (val == null) return true;
+    var result = false;
+    if (val is Iterable) {
+      result = val.isEmpty;
+    } else if (val is String) {
+      result = val.isEmpty;
+    } else if (val is Map) {
+      result = val.isEmpty;
+    }
+    return result;
+  }
+
+  void _fillEmptyStatus() {
+    _status = _isNullOrEmpty(_value) ? RxStatus.loading() : RxStatus.success();
+  }
+
+  RxStatus get status {
+    notifyChildrens();
+    return _status ??= _status = RxStatus.loading();
+  }
 
 
   T get value {
   T get value {
     notifyChildrens();
     notifyChildrens();
     return _value;
     return _value;
   }
   }
 
 
-  @override
-  String toString() => value.toString();
-
-  T _value;
-
   set value(T newValue) {
   set value(T newValue) {
     if (_value == newValue) return;
     if (_value == newValue) return;
     _value = newValue;
     _value = newValue;
-    updater();
+    refresh();
+  }
+
+  @protected
+  void change(T newState, {RxStatus status}) {
+    var _canUpdate = false;
+    if (status != null) {
+      _status = status;
+      _canUpdate = true;
+    }
+    if (newState != _value) {
+      _value = newState;
+      _canUpdate = true;
+    }
+    if (_canUpdate) {
+      refresh();
+    }
+  }
+}
+
+class Value<T> extends ListNotifier
+    with StatusMixin<T>
+    implements ValueListenable<T> {
+  Value(T val) {
+    _value = val;
+    _fillEmptyStatus();
   }
   }
 
 
   void update(void fn(T value)) {
   void update(void fn(T value)) {
     fn(value);
     fn(value);
-    updater();
+    refresh();
   }
   }
+
+  @override
+  String toString() => value.toString();
+
+  dynamic toJson() => (value as dynamic)?.toJson();
 }
 }
 
 
 extension ReactiveT<T> on T {
 extension ReactiveT<T> on T {
@@ -36,10 +84,9 @@ extension ReactiveT<T> on T {
 
 
 typedef Condition = bool Function();
 typedef Condition = bool Function();
 
 
-abstract class GetNotifier<T> extends Value<T> with GetLifeCycle {
+abstract class GetNotifier<T> extends Value<T> with GetLifeCycleBase {
   GetNotifier(T initial) : super(initial) {
   GetNotifier(T initial) : super(initial) {
-    initLifeCycle();
-    _fillEmptyStatus();
+    $configureLifeCycle();
   }
   }
 
 
   @override
   @override
@@ -48,32 +95,9 @@ abstract class GetNotifier<T> extends Value<T> with GetLifeCycle {
     super.onInit();
     super.onInit();
     SchedulerBinding.instance?.addPostFrameCallback((_) => onReady());
     SchedulerBinding.instance?.addPostFrameCallback((_) => onReady());
   }
   }
+}
 
 
-  RxStatus _status;
-
-  bool get isNullOrEmpty {
-    if (_value == null) return true;
-    dynamic val = _value;
-    var result = false;
-    if (val is Iterable) {
-      result = val.isEmpty;
-    } else if (val is String) {
-      result = val.isEmpty;
-    } else if (val is Map) {
-      result = val.isEmpty;
-    }
-    return result;
-  }
-
-  void _fillEmptyStatus() {
-    _status = isNullOrEmpty ? RxStatus.loading() : RxStatus.success();
-  }
-
-  RxStatus get status {
-    notifyChildrens();
-    return _status;
-  }
-
+extension StateExt<T> on StatusMixin<T> {
   Widget call(NotifierBuilder<T> widget, {Widget onError, Widget onLoading}) {
   Widget call(NotifierBuilder<T> widget, {Widget onError, Widget onLoading}) {
     assert(widget != null);
     assert(widget != null);
     return SimpleBuilder(builder: (_) {
     return SimpleBuilder(builder: (_) {
@@ -86,24 +110,6 @@ abstract class GetNotifier<T> extends Value<T> with GetLifeCycle {
       }
       }
     });
     });
   }
   }
-
-  @protected
-  void change(T newState, {RxStatus status}) {
-    var _canUpdate = false;
-    if (status != null) {
-      _status = status;
-      _canUpdate = true;
-    }
-    if (newState != _value) {
-      _value = newState;
-      _canUpdate = true;
-    }
-    if (_canUpdate) {
-      updater();
-    }
-  }
-
-  dynamic toJson() => (value as dynamic)?.toJson();
 }
 }
 
 
 class RxStatus {
 class RxStatus {

-import 'dart:collection';
 import 'package:flutter/material.dart';
 import 'package:flutter/material.dart';
 import '../../../get_core/get_core.dart';
 import '../../../get_core/get_core.dart';
 import '../../../get_instance/src/get_instance.dart';
 import '../../../get_instance/src/get_instance.dart';
 import '../../get_state_manager.dart';
 import '../../get_state_manager.dart';
-
-// Changed to VoidCallback.
-//typedef Disposer = void Function();
-
-// replacing StateSetter, return if the Widget is mounted for extra validation.
-// if it brings overhead the extra call,
-typedef GetStateUpdate = void Function();
-//typedef GetStateUpdate = void Function(VoidCallback fn);
+import 'list_notifier.dart';
 
 
 /// Complies with [GetStateUpdater]
 /// Complies with [GetStateUpdater]
 ///
 ///
@@ -31,14 +23,8 @@ mixin GetStateUpdaterMixin<T extends StatefulWidget> on State<T> {
   }
   }
 }
 }
 
 
-class GetxController extends DisposableInterface {
-  final _updaters = <GetStateUpdate>[];
-
-//  final _updatersIds = HashMap<String, StateSetter>(); //<old>
-  final _updatersIds = HashMap<String, GetStateUpdate>();
-
-  final _updatersGroupIds = HashMap<String, List<GetStateUpdate>>();
-
+// ignore: prefer_mixin
+class GetxController extends DisposableInterface with ListNotifier {
   /// Rebuilds [GetBuilder] each time you call [update()];
   /// Rebuilds [GetBuilder] each time you call [update()];
   /// Can take a List of [ids], that will only update the matching
   /// Can take a List of [ids], that will only update the matching
   /// `GetBuilder( id: )`,
   /// `GetBuilder( id: )`,
@@ -49,73 +35,13 @@ class GetxController extends DisposableInterface {
       return;
       return;
     }
     }
     if (ids == null) {
     if (ids == null) {
-//      _updaters?.forEach((rs) => rs(() {})); //<old>
-      for (final updater in _updaters) {
-        updater();
-      }
+      refresh();
     } else {
     } else {
-      // @jonny, remove this commented code if it's not more optimized.
-//      for (final id in ids) {
-//        if (_updatersIds[id] != null) _updatersIds[id]();
-//        if (_updatersGroupIds[id] != null)
-//          for (final rs in _updatersGroupIds[id]) rs();
-//      }
-
       for (final id in ids) {
       for (final id in ids) {
-        _updatersIds[id]?.call();
-        // ignore: avoid_function_literals_in_foreach_calls
-        _updatersGroupIds[id]?.forEach((rs) => rs());
+        refreshGroup(id);
       }
       }
     }
     }
   }
   }
-
-//  VoidCallback addListener(StateSetter listener) {//<old>
-  VoidCallback addListener(GetStateUpdate listener) {
-    _updaters.add(listener);
-    return () => _updaters.remove(listener);
-  }
-
-//  VoidCallback addListenerId(String key, StateSetter listener) {//<old>
-  VoidCallback addListenerId(String key, GetStateUpdate listener) {
-//    _printCurrentIds();
-    if (_updatersIds.containsKey(key)) {
-      _updatersGroupIds[key] ??= <GetStateUpdate>[];
-      _updatersGroupIds[key].add(listener);
-      return () {
-        _updatersGroupIds[key].remove(listener);
-      };
-    } else {
-      _updatersIds[key] = listener;
-      return () => _updatersIds.remove(key);
-    }
-  }
-
-  /// To dispose an [id] from future updates(), this ids are registered
-  /// by [GetBuilder()] or similar, so is a way to unlink the state change with
-  /// the Widget from the Controller.
-  void disposeId(String id) {
-    _updatersIds.remove(id);
-    _updatersGroupIds.remove(id);
-  }
-
-  /// Remove this after checking the new implementation makes sense.
-  /// Uncomment this if you wanna control the removal of ids..
-  ///  bool _debugging = false;
-  /// Future<void> _printCurrentIds() async {
-  /// if (_debugging) return;
-  /// _debugging = true;
-  /// print('about to debug...');
-  /// await Future.delayed(Duration(milliseconds: 10));
-  /// int totalGroups = 0;
-  /// _updatersGroupIds.forEach((key, value) {
-  /// totalGroups += value.length;
-  /// });
-  /// int totalIds = _updatersIds.length;
-  /// print(
-  ///     'Total: ${totalIds + totalGroups},'+
-  ///     'in groups:$totalGroups, solo ids:$totalIds',);
-  /// _debugging = false;
-  /// }
 }
 }
 
 
 typedef GetControllerBuilder<T extends DisposableInterface> = Widget Function(
 typedef GetControllerBuilder<T extends DisposableInterface> = Widget Function(
@@ -187,10 +113,6 @@ class _GetBuilderState<T extends GetxController> extends State<GetBuilder<T>>
       controller?.onStart();
       controller?.onStart();
     }
     }
 
 
-    // if (widget.global && Get.smartManagement ==
-    //SmartManagement.onlyBuilder) {
-    //   controller?.onStart();
-    // }
     _subscribeToController();
     _subscribeToController();
   }
   }
 
 
@@ -200,20 +122,10 @@ class _GetBuilderState<T extends GetxController> extends State<GetBuilder<T>>
   void _subscribeToController() {
   void _subscribeToController() {
     remove?.call();
     remove?.call();
     remove = (widget.id == null)
     remove = (widget.id == null)
-//        ? controller?.addListener(setState) //<old>
-//        : controller?.addListenerId(widget.id, setState); //<old>
         ? controller?.addListener(getUpdate)
         ? controller?.addListener(getUpdate)
         : controller?.addListenerId(widget.id, getUpdate);
         : controller?.addListenerId(widget.id, getUpdate);
   }
   }
 
 
-  /// Sample for [GetStateUpdate] when you don't wanna
-  /// use [GetStateHelper mixin].
-  ///  bool _getUpdater() {
-  ///    final _mounted = mounted;
-  ///    if (_mounted) setState(() {});
-  ///    return _mounted;
-  ///  }
-
   @override
   @override
   void dispose() {
   void dispose() {
     super.dispose();
     super.dispose();
@@ -249,26 +161,6 @@ class _GetBuilderState<T extends GetxController> extends State<GetBuilder<T>>
   Widget build(BuildContext context) => widget.builder(controller);
   Widget build(BuildContext context) => widget.builder(controller);
 }
 }
 
 
-/// This is a experimental feature.
-/// Meant to be used with SimpleBuilder, it auto-registers the variable
-/// like Rx() does with Obx().
-// class Value<T> extends GetxController {
-//   Value([this._value]);
-
-//   T _value;
-
-//   T get value {
-//     TaskManager.instance.notify(_updaters);
-//     return _value;
-//   }
-
-//   set value(T newValue) {
-//     if (_value == newValue) return;
-//     _value = newValue;
-//     update();
-//   }
-// }
-
 /// It's Experimental class, the Api can be change
 /// It's Experimental class, the Api can be change
 abstract class GetState<T> extends GetxController {
 abstract class GetState<T> extends GetxController {
   GetState(T initialValue) {
   GetState(T initialValue) {

@@ -146,5 +146,3 @@
 //    return widget.builder(controller.state);
 //    return widget.builder(controller.state);
 //  }
 //  }
 //}
 //}
-
-

+import 'dart:collection';
 import 'package:flutter/foundation.dart';
 import 'package:flutter/foundation.dart';
+import 'package:flutter/widgets.dart';
 
 
-import 'simple_builder.dart';
+// This callback remove the listener on addListener function
+typedef Disposer = void Function();
+
+// replacing StateSetter, return if the Widget is mounted for extra validation.
+// if it brings overhead the extra call,
+typedef GetStateUpdate = void Function();
 
 
 class ListNotifier implements Listenable {
 class ListNotifier implements Listenable {
-  List<VoidCallback> _listeners = <VoidCallback>[];
+  List<GetStateUpdate> _updaters = <GetStateUpdate>[];
+
+  HashMap<String, List<GetStateUpdate>> _updatersGroupIds =
+      HashMap<String, List<GetStateUpdate>>();
 
 
   @protected
   @protected
-  void updater() {
+  void refresh() {
     assert(_debugAssertNotDisposed());
     assert(_debugAssertNotDisposed());
-    for (var element in _listeners) {
+    for (var element in _updaters) {
       element();
       element();
     }
     }
   }
   }
 
 
+  @protected
+  void refreshGroup(String id) {
+    assert(_debugAssertNotDisposed());
+    if (_updatersGroupIds.containsKey(id)) {
+      for (var item in _updatersGroupIds[id]) {
+        item();
+      }
+    }
+  }
+
   bool _debugAssertNotDisposed() {
   bool _debugAssertNotDisposed() {
     assert(() {
     assert(() {
-      if (_listeners == null) {
+      if (_updaters == null) {
         throw FlutterError('''A $runtimeType was used after being disposed.\n
         throw FlutterError('''A $runtimeType was used after being disposed.\n
 'Once you have called dispose() on a $runtimeType, it can no longer be used.''');
 'Once you have called dispose() on a $runtimeType, it can no longer be used.''');
       }
       }
@@ -26,29 +46,87 @@ class ListNotifier implements Listenable {
 
 
   @protected
   @protected
   void notifyChildrens() {
   void notifyChildrens() {
-    TaskManager.instance.notify(_listeners);
+    TaskManager.instance.notify(_updaters);
   }
   }
 
 
   bool get hasListeners {
   bool get hasListeners {
     assert(_debugAssertNotDisposed());
     assert(_debugAssertNotDisposed());
-    return _listeners.isNotEmpty;
+    return _updaters.isNotEmpty;
   }
   }
 
 
   @override
   @override
-  void addListener(VoidCallback listener) {
+  void removeListener(VoidCallback listener) {
     assert(_debugAssertNotDisposed());
     assert(_debugAssertNotDisposed());
-    _listeners.add(listener);
+    _updaters.remove(listener);
   }
   }
 
 
-  @override
-  void removeListener(VoidCallback listener) {
+  void removeListenerId(String id, VoidCallback listener) {
     assert(_debugAssertNotDisposed());
     assert(_debugAssertNotDisposed());
-    _listeners.remove(listener);
+    if (_updatersGroupIds.containsKey(id)) {
+      _updatersGroupIds[id].remove(listener);
+    }
+    _updaters.remove(listener);
   }
   }
 
 
   @mustCallSuper
   @mustCallSuper
   void dispose() {
   void dispose() {
     assert(_debugAssertNotDisposed());
     assert(_debugAssertNotDisposed());
-    _listeners = null;
+    _updaters = null;
+    _updatersGroupIds = null;
+  }
+
+  @override
+  Disposer addListener(GetStateUpdate listener) {
+    assert(_debugAssertNotDisposed());
+    _updaters.add(listener);
+    return () => _updaters.remove(listener);
+  }
+
+  Disposer addListenerId(String key, GetStateUpdate listener) {
+    _updatersGroupIds[key] ??= <GetStateUpdate>[];
+    _updatersGroupIds[key].add(listener);
+    return () => _updatersGroupIds[key].remove(listener);
+  }
+
+  /// To dispose an [id] from future updates(), this ids are registered
+  /// by [GetBuilder()] or similar, so is a way to unlink the state change with
+  /// the Widget from the Controller.
+  void disposeId(String id) {
+    _updatersGroupIds.remove(id);
+  }
+}
+
+class TaskManager {
+  TaskManager._();
+
+  static TaskManager _instance;
+
+  static TaskManager get instance => _instance ??= TaskManager._();
+
+  GetStateUpdate _setter;
+
+  List<VoidCallback> _remove;
+
+  void notify(List<GetStateUpdate> _updaters) {
+    if (_setter != null) {
+      if (!_updaters.contains(_setter)) {
+        _updaters.add(_setter);
+        _remove.add(() => _updaters.remove(_setter));
+      }
+    }
+  }
+
+  Widget exchange(
+    List<VoidCallback> disposers,
+    GetStateUpdate setState,
+    Widget Function(BuildContext) builder,
+    BuildContext context,
+  ) {
+    _remove = disposers;
+    _setter = setState;
+    final result = builder(context);
+    _remove = null;
+    _setter = null;
+    return result;
   }
   }
 }
 }

 import 'dart:async';
 import 'dart:async';
 import 'package:flutter/widgets.dart';
 import 'package:flutter/widgets.dart';
 import 'get_state.dart';
 import 'get_state.dart';
+import 'list_notifier.dart';
 
 
 typedef ValueBuilderUpdateCallback<T> = void Function(T snapshot);
 typedef ValueBuilderUpdateCallback<T> = void Function(T snapshot);
 typedef ValueBuilderBuilder<T> = Widget Function(
 typedef ValueBuilderBuilder<T> = Widget Function(
@@ -87,7 +88,7 @@ class SimpleBuilder extends StatefulWidget {
 
 
 class _SimpleBuilderState extends State<SimpleBuilder>
 class _SimpleBuilderState extends State<SimpleBuilder>
     with GetStateUpdaterMixin {
     with GetStateUpdaterMixin {
-  final disposers = <VoidCallback>[];
+  final disposers = <Disposer>[];
 
 
   @override
   @override
   void dispose() {
   void dispose() {
@@ -107,38 +108,3 @@ class _SimpleBuilderState extends State<SimpleBuilder>
     );
     );
   }
   }
 }
 }
-
-class TaskManager {
-  TaskManager._();
-
-  static TaskManager _instance;
-
-  static TaskManager get instance => _instance ??= TaskManager._();
-
-  GetStateUpdate _setter;
-
-  List<VoidCallback> _remove;
-
-  void notify(List<GetStateUpdate> _updaters) {
-    if (_setter != null) {
-      if (!_updaters.contains(_setter)) {
-        _updaters.add(_setter);
-        _remove.add(() => _updaters.remove(_setter));
-      }
-    }
-  }
-
-  Widget exchange(
-    List<VoidCallback> disposers,
-    GetStateUpdate setState,
-    Widget Function(BuildContext) builder,
-    BuildContext context,
-  ) {
-    _remove = disposers;
-    _setter = setState;
-    final result = builder(context);
-    _remove = null;
-    _setter = null;
-    return result;
-  }
-}

@@ -9,7 +9,6 @@ environment:
 dependencies:
 dependencies:
   flutter:
   flutter:
     sdk: flutter
     sdk: flutter
-  meta: 1.3.0-nullsafety.3
 
 
 dev_dependencies:
 dev_dependencies:
   flutter_test:
   flutter_test:

@@ -9,11 +9,7 @@ class Mock {
   }
   }
 }
 }
 
 
-class DisposableController with GetLifeCycle {
-  DisposableController() {
-    initLifeCycle();
-  }
-}
+class DisposableController extends GetLifeCycle {}
 
 
 // ignore: one_member_abstracts
 // ignore: one_member_abstracts
 abstract class Service {
 abstract class Service {