an_state 1.1.0

A reactive state management library for Flutter, providing seamless integration between ViewModels, Widgets, and reactive observables.

an_state

an_state is a powerful, lightweight reactive state management library for Flutter. It seamlessly integrates the high-performance reactive engine of an_reactive_state, the robust lifecycle management of an_viewmodel, and the elegant state persistence of remember.

Important

an_state strongly depends on anlifecycle. All core features, including rememberState, rememberMutableState, and context.viewModels(), require a valid Lifecycle context provided within the widget tree.

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🚀 Key Features

• 🎯 Transparent Reactivity: Based on an_reactive_state, UI updates automatically when state changes. No notifyListeners() or setState() required.
• 🧬 Lifecycle-Aware: States are bound to the lifecycle of ViewModels or Widgets, ensuring zero memory leaks through automatic resource cleanup.
• 🏗️ Structured State: Provides RState for mutable values and ComputedState for derived data with automatic dependency tracking.
• 🔄 Compose-like DX: Use rememberMutableState to persist reactive state across widget rebuilds, offering a developer experience similar to Jetpack Compose.
• 🛠️ Bridge Utilities: Easily convert legacy ValueNotifier or ChangeNotifier into modern reactive sources.

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📦 Getting Started

Installation

Add the dependency to your pubspec.yaml:

dependencies:
  an_state: ^0.0.1

Mandatory Lifecycle Setup

Initialize the lifecycle system at the root of your application:

import 'package:anlifecycle/anlifecycle.dart';

void main() {
  runApp(
    LifecycleApp( // 1. Wrap with LifecycleApp
      child: MaterialApp(
        // 2. Add the navigator observer
        navigatorObservers: [LifecycleNavigatorObserver.hookMode()],
        home: const HomePage(),
      ),
    ),
  );
}

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📖 Usage Guide

1. In ViewModels (Business Logic)

Define your states using stateMutableOf and stateOf. These states will be automatically disposed of when the ViewModel is cleared.

class UserViewModel extends ViewModel {
  // Use stateValueOf to initialize mutable state
  late final username = stateMutableOf(stateValueOf("Guest"));
  
  // Computed state depends on username
  late final greeting = stateOf(() => "Hello, ${username.value}!");

  void updateName(String newName) {
    username.value = newName; // UI updates automatically
  }
}

2. In Widgets (UI Layer)

Access ViewModels and observe states with minimal boilerplate.

@override
Widget build(BuildContext context) {
  // Fetch ViewModel via extension (requires Lifecycle context)
  final vm = context.viewModels<UserViewModel>(factory: UserViewModel.new);
  
  // Use listenRawState to subscribe to changes and get the current value
  final name = context.listenRawState(vm.username);
  final message = context.listenRawState(vm.greeting);

  return Column(
    children: [
      Text(message),
      TextField(onChanged: vm.updateName),
    ],
  );
}

3. Local Widget State

For UI-only state (like a toggle or a counter), use remember extensions to avoid boilerplate StatefulWidgets.

@override
Widget build(BuildContext context) {
  // Persists across rebuilds, disposed when the widget is removed from the tree
  // Requires Lifecycle context
  final isExpanded = context.rememberMutableState(stateValueOf(false));

  return Column(
    children: [
      Text("Details are ${isExpanded.value ? 'Visible' : 'Hidden'}"),
      ElevatedButton(
        onPressed: () => isExpanded.value = !isExpanded.value,
        child: const Text("Toggle"),
      ),
    ],
  );
}

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🛠️ Advanced Tools

Initializers

• stateValueOf(T value): Creates an initializer for a simple value.
• stateListOf(List<T> list): Initializer for a reactive list.
• stateMapOf(Map<K, V> map): Initializer for a reactive map.

Bridge Tools

• stateOfValueNotifier(ValueNotifier<T> notifier): Converts a ValueNotifier into a reactive computer.
• stateOfChangeNotifier(...): Converts any ChangeNotifier into a reactive computer.
• stateOfAsync({required T initialValue, Future<T>? future, Stream<T>? steam}): Converts a Future or Stream into a reactive computer. Returns initialValue until an async value is received.

Optimization

• expensiveComputation(Computer<T> computer): Ensures a heavy calculation or registration logic runs only once during the state's lifecycle.

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📋 Core API Reference

Method	Source	Description
stateMutableOf(init)	ViewModel	Creates a mutable RState bound to ViewModel.
stateOf(computer)	ViewModel	Creates a read-only ComputedState.
rememberMutableState(init)	BuildContext	Remembers a mutable state in the widget tree.
rememberState(computer)	BuildContext	Remembers a computed state in the widget tree.
listenRawState(state)	BuildContext	Watches a state and returns its value (triggers rebuild).
stateOfAsync(...)	Utility	Converts a Future or Stream into a reactive computer.

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📄 License

This project is licensed under the Apache 2.0 License - see the LICENSE file for details.