fix:

- Listen other notifiers after the first value;
- Do not emmit repeated values;

lib/src/value_selector.dart

@@ -1,44 +1,63 @@
-part of '../value_selectable.dart';
+import 'package:flutter/foundation.dart';
 
 /// A selector that computes a synchronous value based on a given scope.
-class ValueSelector<T> extends ValueSelectable<T> {
+class ValueSelector<T> extends ChangeNotifier implements ValueListenable<T> {
   final T Function(GetValue get) scope;
-  final Function? _set;
-  late final bool kActionWithArguments;
   late T _value;
+  final _listenables = <Listenable>{};
 
   @override
   T get value => _value;
 
-  set value(dynamic newValue) {
-    if (_set != null) {
-      Function.apply(_set!, kActionWithArguments ? [newValue] : []);
+  late final _get = GetValue._(onListenableIdentified);
+
+  void onListenableIdentified(Listenable listenable) {
+    if (_listenables.add(listenable)) {
+      listenable.addListener(notifyListeners);
     }
   }
 
-  late final _get = GetValue._(notifyListeners);
-
   /// Constructs a ValueSelector with an initial value and a scope function.
-  ValueSelector(this.scope, [this._set]) {
-    if (_set != null) {
-      var funcText = _set.runtimeType.toString();
-      assert(!funcText.contains(','), 'Function must have one argument.');
-      kActionWithArguments = !funcText.startsWith('() =>');
-    }
-
+  ValueSelector(this.scope) {
     _value = scope(_get);
-    _get._tracking = false;
   }
 
   @override
   void notifyListeners() {
-    _value = scope(_get);
+    _listenables.clear();
+    final newValue = scope(_get);
+
+    if (newValue == _value) return;
+    _value = newValue;
     super.notifyListeners();
   }
 
   @override
   void dispose() {
     _get.dispose();
+    for (var listenable in _listenables) {
+      listenable.removeListener(notifyListeners);
+    }
     super.dispose();
   }
 }
+
+/// Helper class to manage value dependencies and tracking for selectors.
+final class GetValue {
+  final void Function(Listenable listenable) _selectorIdentifyListenable;
+  GetValue._(this._selectorIdentifyListenable);
+
+  bool _isDisposed = false;
+
+  /// Registers a notifier and returns its value.
+  R call<R>(ValueListenable<R> notifier) {
+    if (_isDisposed) throw Exception('It is disposed');
+    _selectorIdentifyListenable.call(notifier);
+    return notifier.value;
+  }
+
+  /// Disposes of all registered listeners.
+  void dispose() {
+    _isDisposed = true;
+  }
+}

lib/value_selectable.dart

@@ -1,12 +1,8 @@
 library value_selectable;
 
-import 'dart:async';
-import 'dart:collection';
-
 import 'package:flutter/foundation.dart';
 
-part 'src/async_value_selector.dart';
-part 'src/value_selector.dart';
+export 'src/value_selector.dart';
 
 /// Abstract class for a selectable value, extending ChangeNotifier.
 abstract class ValueSelectable<T> extends ChangeNotifier
@@ -16,27 +12,20 @@ typedef SetValue<T> = void Function(T value);
 
 /// Helper class to manage value dependencies and tracking for selectors.
 final class GetValue {
-  final void Function() _selectorNotifyListeners;
-  final List<void Function()> _disposers = [];
-  var _tracking = true;
-  bool _isDisposed = false;
+  final void Function(Listenable listenable) _selectorIdentifyListenable;
+  GetValue._(this._selectorIdentifyListenable);
 
-  GetValue._(this._selectorNotifyListeners);
+  bool _isDisposed = false;
 
   /// Registers a notifier and returns its value.
   R call<R>(ValueListenable<R> notifier) {
-    if (_tracking) {
-      notifier.addListener(_selectorNotifyListeners);
-      _disposers.add(() => notifier.removeListener(_selectorNotifyListeners));
-    }
+    if (_isDisposed) throw Exception('It is disposed');
+    _selectorIdentifyListenable.call(notifier);
     return notifier.value;
   }
 
   /// Disposes of all registered listeners.
   void dispose() {
     _isDisposed = true;
-    for (final disposer in _disposers) {
-      disposer();
-    }
   }
 }

test/src/value_selector_test.dart

@@ -5,50 +5,62 @@ import 'package:value_selectable/value_selectable.dart';
 void main() {
   test('ValueSelectable', () async {
     final counterState = ValueNotifier<int>(0);
-
-    final selectorState = ValueSelector<int>(
-      (get) => get(counterState) + 1,
-      (String action) {
-        if (action == 'INCREMENT') counterState.value++;
-        if (action == 'DECREMENT') counterState.value--;
-      },
-    );
+    final selectorState = ValueSelector<int>((get) => get(counterState) + 1);
 
     selectorState.addListener(expectAsync0(() {
       expect(selectorState.value, anyOf([2, 3]));
-    }, count: 3));
+    }, count: 2));
 
     // directly change
     counterState.value = 1;
+    counterState.value = 2;
 
-    // indirectly change
-    selectorState.value = 'INCREMENT';
-    selectorState.value = 'DECREMENT';
-
-    await Future.delayed(const Duration(seconds: 1));
+    // await Future.delayed(const Duration(seconds: 1));
     selectorState.dispose();
   });
 
-  test('ValueSelectable throw assert if reducer has more one arguments', () async {
-    expect(() {
-      return ValueSelector<int>(
-        (get) => 1,
-        (String action, int id) {},
-      );
-    }, throwsAssertionError);
-  });
-
   test('ValueSelectable action zero arguments', () async {
-    ValueSelector<int>(
-      (get) => 1,
-      () {},
-    );
+    ValueSelector<int>((get) => 1);
   });
 
   test('ValueSelectable action one arguments', () async {
-    ValueSelector<int>(
-      (get) => 1,
-      (String action) {},
-    );
+    final counterState = ValueNotifier<int>(0);
+    ValueSelector<int>((get) => get(counterState));
+  });
+
+  test('Listen other notifiers after the first value', () {
+    final nameState = ValueNotifier('Deivão');
+    final ageState = ValueNotifier(15);
+
+    final canAccess = ValueSelector((get) {
+      if (get(nameState) == 'Deivão') return true;
+      if (get(ageState) >= 18) return true;
+      return false;
+    });
+
+    canAccess.addListener(() => print('Can access: ${canAccess.value}'));
+
+    // Return false
+    nameState.value = "Jacob";
+
+    // Return true (doesn't work)
+    ageState.value = 18;
+  });
+
+  test('Do not emmit repeated values', () {
+    final nameState = ValueNotifier('Jacob');
+    final ageState = ValueNotifier(17);
+
+    final canAccess = ValueSelector((get) {
+      print('scope');
+      if (get(nameState) == 'Deivão') return true;
+      if (get(ageState) >= 18) return true;
+      return false;
+    });
+
+    canAccess.addListener(() => print('Can access: ${canAccess.value}'));
+
+    nameState.value = "Deivão";
+    ageState.value = 17;
   });
 }