Custom State dilemma

[busslina]

I have a CustomState that I have been ussing in most of my Flutter stateful widget for a while.

Today I started with Riverpod. I will have to use ConsumerState. So my dilema is to choose one solution. Possible solutions:

1. Create a CustomConsumerState class as copy of CustomState. Is my provisional solution but I don't like it.
2. Moving the most of the code from CustomState to a new CustomState mixin and using it in CustomState and ConsumerCustomState.
   For me it would be perfect choice but I think it is not possible due to the constructor data. (Yes, that data could maybe refactored into
   abstract getter functions, but I don't know yet if this solution is possible).
3. Using Riverpod Consumer as a mixin. I don't know if exists this possibility, like with Equatable and Equatable mixin.
4. Using only CustomConsumerState in all widgets, even if they are not accessing providers. I don't know if it would be much less efficient
   and if adding Riverpod in all my projects, even if they didn't use it, would affect the performance.
5. Implement Riverpod logic on my CustomState in order to be able to use the read and watch methods

Any help, advice or other possible solution are appreciated.

import 'dart:async';

import 'package:busslina_dart_lightweight_lib/busslina_dart_lightweight_lib.dart'
    as llib;
import 'package:busslina_flutter_lightweight_lib/busslina_flutter_lightweight_lib.dart';

import 'package:flutter/material.dart';
import 'package:back_button_interceptor/back_button_interceptor.dart';

abstract class CustomState<T extends StatefulWidget> extends State<T> {
  // Data

  //#region
  final Set<ChangeNotifier> _changeNotifiers;
  final Set<llib.Notifier> _notifiers;
  final bool interceptBackButton;
  final int? interceptBackButtonZIndex;
  final bool interceptBackButtonIfNotYetIntercepted;
  //#endregion

  /// Constructor.
  CustomState({
    Set<ChangeNotifier>? changeNotifiers,
    Set<llib.Notifier<dynamic>>? notifiers,
    this.interceptBackButton = false,
    this.interceptBackButtonZIndex,
    this.interceptBackButtonIfNotYetIntercepted = true,
  })  : _changeNotifiers = changeNotifiers ?? {},
        _notifiers = notifiers ?? {},
        super();

  // Inherited functions
  //
  // - 01 - Init state
  // - 02 - Dispose

  //#region
  /// 01 - Init state.
  @override
  void initState() {
    // [01]: Super execution
    super.initState();

    // [02]: Back button interceptor
    if (interceptBackButton) {
      BackButtonInterceptor.add(
        backButtonInterceptor,
        zIndex: interceptBackButtonZIndex,
        ifNotYetIntercepted: interceptBackButtonIfNotYetIntercepted,
      );
    }

    // [03]: Subscribing to change notifiers
    for (final changeNotifier in _changeNotifiers) {
      changeNotifier.addListener(refresh);
    }

    // [04]: Subscribing to notifiers
    for (final notifier in _notifiers) {
      notifier.addListener(_notifierListener);
    }

    // [05]: Post build callback
    setPostFrameCallback(afterBuild);
  }

  /// 02 - Dispose.
  @override
  void dispose() {
    // [01]: Back button interceptor
    if (interceptBackButton) {
      BackButtonInterceptor.remove(backButtonInterceptor);
    }

    // [02]: Unsubscribing from change notifiers
    for (final changeNotifier in _changeNotifiers) {
      changeNotifier.removeListener(refresh);
    }

    // [03]: Unsubscribing from notifiers
    for (final notifier in _notifiers) {
      notifier.removeListener(_notifierListener);
    }

    // [04]: Super execution
    super.dispose();
  }
  //#endregion

  // Functions
  //
  // - 01 - After build
  // - 02 - Before refresh
  // - 03 - Refresh
  // - 04 - Add change notifier
  // - 05 - Add notifier
  // - 06 - Remove change notifier
  // - 07 - Remove notifier
  // - 08 - Back button interceptor

  //#region
  /// 01 - After build.
  FutureOr<void> afterBuild() {}

  /// 02 - Before refresh.
  FutureOr<void> beforeRefresh() {}

  /// 03 - Refresh.
  FutureOr<bool> refresh(
      {bool active = true, bool errorIfNotMounted = true}) async {
    // [A]: Not mounted
    if (!mounted) {
      if (errorIfNotMounted) {
        throw ('Not mounted');
      }
      return false;
    }

    // [B]: Active
    if (active) {
      // Executing before refresh function
      await beforeRefresh();

      setState(() {});

      return true;
    }

    // [C]: Not active
    return false;
  }

  /// 04 - Add change notifier.
  void addChangeNotifier(ChangeNotifier notifier) {
    if (!_changeNotifiers.add(notifier)) {
      return;
    }

    notifier.addListener(refresh);
  }

  /// 05 - Add notifier.
  void addNotifier(llib.Notifier notifier) {
    if (!_notifiers.add(notifier)) {
      return;
    }

    notifier.addListener(_notifierListener);
  }

  /// 06 - Remove change notifier.
  void removeChangeNotifier(ChangeNotifier notifier) {
    if (!_changeNotifiers.remove(notifier)) {
      return;
    }

    notifier.removeListener(refresh);
  }

  /// 07 - Remove notifier.
  void removeNotifier(llib.Notifier notifier) {
    if (!_notifiers.remove(notifier)) {
      return;
    }

    notifier.removeListener(_notifierListener);
  }

  /// 08 - Back button interceptor.
  FutureOr<bool> backButtonInterceptor(
    bool stopDefaultButtonEvent,
    RouteInfo info,
  ) =>
      false;
  //#endregion

  //#region
  /// 01 - Notifier listener.
  void _notifierListener(_) => refresh();
  //#endregion
}

[hamza-imran75]

Why not use consumer only?
https://docs-v2.riverpod.dev/docs/from_provider/provider_vs_riverpod#there-is-no-consumern-equivalent-in-riverpod

[busslina]

Why not use consumer only? https://docs-v2.riverpod.dev/docs/from_provider/provider_vs_riverpod#there-is-no-consumern-equivalent-in-riverpod

Your link is down

[hamza-imran75]

Sorry

https://docs-v2.riverpod.dev/docs/from_provider/provider_vs_riverpod#there-is-no-consumern-equivalent-in-riverpod

[busslina]

No worries, thank you. I will take a look on this

[busslina]

I reached a solution. Is the case (2.). It wasn't as complicated as I thought. Anyway, I'm open to better solutions.

1. CustomStateMixin:

mixin CustomStateMixin<T extends StatefulWidget> on State<T> {
  // Abstract getter functions
  //
  // - 01 - Change notifiers
  // - 02 - Notifiers
  // - 03 - Intercept back button
  // - 04 - Intercept back button Z Index
  // - 05 - Intercept back button if not yet intercepted

  //#region
  /// 01 - Change notifiers
  Set<ChangeNotifier> get changeNotifiers;

  /// 02 - Notifiers
  Set<llib.Notifier> get notifiers;

  /// 03 - Intercept back button
  bool get interceptBackButton;

  /// 04 - Intercept back button Z Index
  int? get interceptBackButtonZIndex;

  /// 05 - Intercept back button if not yet intercepted
  bool get interceptBackButtonIfNotYetIntercepted;

  //#endregion

  // Override functions
  //
  // - 01 - Init state
  // - 02 - Dispose

  //#region
  /// 01 - Init state.
  @override
  void initState() {
    // [01]: Super execution
    super.initState();

    // [02]: Back button interceptor
    if (interceptBackButton) {
      BackButtonInterceptor.add(
        backButtonInterceptor,
        zIndex: interceptBackButtonZIndex,
        ifNotYetIntercepted: interceptBackButtonIfNotYetIntercepted,
      );
    }

    // [03]: Subscribing to change notifiers
    for (final changeNotifier in changeNotifiers) {
      changeNotifier.addListener(refresh);
    }

    // [04]: Subscribing to notifiers
    for (final notifier in notifiers) {
      notifier.addListener(_notifierListener);
    }

    // [05]: Post build callback
    setPostFrameCallback(afterBuild);
  }

  /// 02 - Dispose.
  @override
  void dispose() {
    // [01]: Back button interceptor
    if (interceptBackButton) {
      BackButtonInterceptor.remove(backButtonInterceptor);
    }

    // [02]: Unsubscribing from change notifiers
    for (final changeNotifier in changeNotifiers) {
      changeNotifier.removeListener(refresh);
    }

    // [03]: Unsubscribing from notifiers
    for (final notifier in notifiers) {
      notifier.removeListener(_notifierListener);
    }

    // [04]: Super execution
    super.dispose();
  }
  //#endregion

  // Functions
  //
  // - 01 - After build
  // - 02 - Before refresh
  // - 03 - Refresh
  // - 04 - Add change notifier
  // - 05 - Add notifier
  // - 06 - Remove change notifier
  // - 07 - Remove notifier
  // - 08 - Back button interceptor

  //#region
  /// 01 - After build.
  FutureOr<void> afterBuild() {}

  /// 02 - Before refresh.
  FutureOr<void> beforeRefresh() {}

  /// 03 - Refresh.
  FutureOr<bool> refresh(
      {bool active = true, bool errorIfNotMounted = true}) async {
    // [A]: Not mounted
    if (!mounted) {
      if (errorIfNotMounted) {
        throw ('Not mounted');
      }
      return false;
    }

    // [B]: Active
    if (active) {
      // Executing before refresh function
      await beforeRefresh();

      setState(() {});

      return true;
    }

    // [C]: Not active
    return false;
  }

  /// 04 - Add change notifier.
  void addChangeNotifier(ChangeNotifier notifier) {
    if (!changeNotifiers.add(notifier)) {
      return;
    }

    notifier.addListener(refresh);
  }

  /// 05 - Add notifier.
  void addNotifier(llib.Notifier notifier) {
    if (!notifiers.add(notifier)) {
      return;
    }

    notifier.addListener(_notifierListener);
  }

  /// 06 - Remove change notifier.
  void removeChangeNotifier(ChangeNotifier notifier) {
    if (!changeNotifiers.remove(notifier)) {
      return;
    }

    notifier.removeListener(refresh);
  }

  /// 07 - Remove notifier.
  void removeNotifier(llib.Notifier notifier) {
    if (!notifiers.remove(notifier)) {
      return;
    }

    notifier.removeListener(_notifierListener);
  }

  /// 08 - Back button interceptor.
  FutureOr<bool> backButtonInterceptor(
    bool stopDefaultButtonEvent,
    RouteInfo info,
  ) =>
      false;
  //#endregion

  //#region
  /// 01 - Notifier listener.
  void _notifierListener(_) => refresh();
  //#endregion
}

2. CustomState:

abstract class CustomState<T extends StatefulWidget> extends State<T>
    with CustomStateMixin<T> {
  // Inherited data

  //#region
  /// 01 - Change notifiers
  @override
  final Set<ChangeNotifier> changeNotifiers;

  /// 02 - Notifiers
  @override
  final Set<llib.Notifier> notifiers;

  /// 03 - Intercept back button
  @override
  final bool interceptBackButton;

  /// 04 - Intercept back button Z Index
  @override
  final int? interceptBackButtonZIndex;

  /// 05 - Intercept back button if not yet intercepted
  @override
  final bool interceptBackButtonIfNotYetIntercepted;
  //#endregion

  /// Constructor.
  CustomState({
    Set<ChangeNotifier>? changeNotifiers,
    Set<llib.Notifier<dynamic>>? notifiers,
    this.interceptBackButton = false,
    this.interceptBackButtonZIndex,
    this.interceptBackButtonIfNotYetIntercepted = true,
  })  : changeNotifiers = changeNotifiers ?? {},
        notifiers = notifiers ?? {},
        super();
}

3. CustomConsumerState:

abstract class CustomConsumerState<T extends ConsumerStatefulWidget>
    extends ConsumerState<T> with CustomStateMixin<T> {
  // Inherited data

  //#region
  /// 01 - Change notifiers
  @override
  final Set<ChangeNotifier> changeNotifiers;

  /// 02 - Notifiers
  @override
  final Set<llib.Notifier> notifiers;

  /// 03 - Intercept back button
  @override
  final bool interceptBackButton;

  /// 04 - Intercept back button Z Index
  @override
  final int? interceptBackButtonZIndex;

  /// 05 - Intercept back button if not yet intercepted
  @override
  final bool interceptBackButtonIfNotYetIntercepted;
  //#endregion

  /// Constructor.
  CustomConsumerState({
    Set<ChangeNotifier>? changeNotifiers,
    Set<llib.Notifier<dynamic>>? notifiers,
    this.interceptBackButton = false,
    this.interceptBackButtonZIndex,
    this.interceptBackButtonIfNotYetIntercepted = true,
  })  : changeNotifiers = changeNotifiers ?? {},
        notifiers = notifiers ?? {},
        super();
}

[lucavenir]

Thanks for sharing your solution - but I'm curious, this CustomState of yours ... was it something you created and used on your own?

[busslina]

Yes, I created it, extending it over the time and using it in almost every StateFul widget. It works great for me. I think the feature that I use the most is the afterBuild() hook.

Now I'm curious about your curiosity haha

[lucavenir]

Nothing fancy at all, I am curious of what motives a person to write custom solutions like that, since there're are alternatives 😄

[busslina]

Well, I don't know any public alternative, you can give me an example? Anyway, it is the same case as extensions. Maybe there are packages that do the same job that my extensions, but there are some reasons to do it by yourself:

1. Tailor made for your needs
2. No wasting time searching and choosing those packages
3. These packages could include much more code than your needs and can have outdated dependencies over the time, etc