mz_core #

A collection of production-ready Flutter and Dart utilities for state management, logging, collections, and rate limiting.

Features #

Installation #

Add to your pubspec.yaml:

dependencies:
  mz_core: ^1.2.0

Then run:

flutter pub get

Quick Start #

State Management with Controllers #

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

// 1. Create a controller
class CounterController with Controller {
  int _count = 0;
  int get count => _count;

  void increment() {
    _count++;
    notifyListeners();
  }
}

// 2. Use in Flutter
class CounterScreen extends StatefulWidget {
  const CounterScreen({super.key});

  @override
  State<CounterScreen> createState() => _CounterScreenState();
}

class _CounterScreenState extends State<CounterScreen> {
  final _controller = CounterController();

  @override
  void dispose() {
    _controller.dispose();  // Automatic cleanup
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: ControllerBuilder<CounterController>(
          controller: _controller,
          builder: (context, ctrl) => Text('Count: ${ctrl.count}'),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _controller.increment,
        child: const Icon(Icons.add),
      ),
    );
  }
}

Automatic Resource Cleanup #

class DataService with AutoDispose {
  late final StreamSubscription _subscription;
  late final Timer _timer;

  DataService() {
    _subscription = dataStream.listen(_onData);
    autoDispose(_subscription.cancel);  // Register cleanup

    _timer = Timer.periodic(duration, (_) => _refresh());
    autoDispose(_timer.cancel);  // Register cleanup
  }

  // dispose() automatically calls all registered cleanups
}

Observable Collections #

final todos = ListenableList<String>(['Buy milk', 'Walk dog']);

todos.addListener(() {
  print('Todos changed: ${todos.length} items');
});

todos.add('Write code');  // Triggers listener
todos.removeAt(0);        // Triggers listener

Structured Logging #

final logger = SimpleLogger(
  output: ConsoleOutput(
    formatter: LogFormatter(enableColors: true),
  ),
  minimumLevel: LogLevel.debug,
);

// Log different severity levels
logger.info('Application started');
logger.warning('Low memory');
logger.error('Network failure');

// Group related logs
await logger.group('user-auth', 'User Authentication', () async {
  logger.debug('Checking credentials');
  await authenticateUser();
  logger.info('User authenticated');
});

Debounce User Input #

class SearchWidget extends StatefulWidget {
  @override
  Widget build(BuildContext context) {
    return TextField(
      onChanged: (query) {
        // Only search after user stops typing for 500ms
        Debouncer.debounce(
          'search',
          const Duration(milliseconds: 500),
          () => performSearch(query),
        );
      },
    );
  }
}

Throttle Button Presses #

class SaveButton extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return ElevatedButton(
      onPressed: () {
        // Can only execute once every 2 seconds
        Throttler.throttle(
          'save_button',
          const Duration(seconds: 2),
          () => saveData(),
        );
      },
      child: const Text('Save'),
    );
  }
}

Memoization #

// Cache API calls with tags (like Debouncer)
Future<User> getCurrentUser() => Memoizer.run(
  'current-user',
  () => api.fetchCurrentUser(),
  ttl: const Duration(minutes: 30),
);

// Key-based caching with dynamic tags
Future<Product> getProduct(String id) => Memoizer.run(
  'product-$id',
  () => api.fetchProduct(id),
);

// Force refresh for pull-to-refresh
Future<User> refreshUser() => Memoizer.run(
  'current-user',
  () => api.fetchCurrentUser(),
  forceRefresh: true,
);

// Invalidate cache
void logout() => Memoizer.clear('current-user');

Example App #

A comprehensive example app demonstrating all features is included in the /example directory.

Run the example:

cd example
flutter run

The example app includes interactive demos for:

• State Management: Controllers with .watch(), key-based notifications, and priority listeners
• Logging System: Multiple output formats (Plain Text, JSON, Compact), log levels, and groups
• Rate Limiting: Debouncing search input, throttling button clicks, and async debouncing
• Observable Collections: ListenableList task manager and ListenableSet tag selector
• Extension Methods: Interactive demonstrations of all extension utilities

Documentation #

Features in Detail #

Controllers Overview #

Type-safe state management with built-in lifecycle:

• Controller mixin for custom state management
• Automatic listener notification with notifyListeners()
• Multiple listener signatures (void, value, key-value)
• Priority and filtered listeners
• Integration with Flutter via ControllerBuilder and .watch()

Use case: Managing app state, form state, feature flags, user data

Auto-Disposal Pattern #

Automatic resource cleanup pattern:

• Mixin-based (AutoDispose)
• Register cleanup functions with autoDispose()
• LIFO cleanup order (last-in-first-out)
• Prevents memory leaks from forgotten disposals

Use case: Cleaning up streams, timers, controllers, file handles

Observable Collections Details #

Listenable versions of standard collections:

• ListenableList<T>: Observable list with full List API
• ListenableSet<T>: Observable set with full Set API
• Automatic listener notification on modifications
• Direct replacement for standard collections

Use case: Todo lists, shopping carts, real-time data displays

Structured Logging Details #

Production-ready logging system:

• Six severity levels (trace, debug, info, warning, error, fatal)
• Log groups for related entries
• Multiple outputs (console, file, JSON, rotating files)
• Sampling, filtering, and minimum level controls
• Colored console output with customizable formatting

Use case: Debug logs, error tracking, audit trails, analytics

Rate Limiting Details #

Control function execution frequency:

• Debouncer: Execute after calls stop (search-as-you-type)
• Throttler: Limit execution frequency (scroll events)
• Debouncer.debounceAsync: Type-safe async debouncing with cancellation

Use case: API rate limiting, UI event handling, auto-save

Extensions Details #

Convenient extension methods:

• Iterable: toMap(), toIndexedMap(), firstWhereWithIndexOrNull()
• List: removeFirstWhere(), removeLastWhere()
• Set: toggle(), replaceAll()
• String: toCapitalizedWords(), toCamelCase(), toSnakeCase()
• num: clampToInt(), roundToPlaces()
• Widget: padding(), center(), expanded()

Examples #

Example 1: Search with Debouncing #

Complete example showing debounced API search:

import 'package:flutter/material.dart';
import 'package:mz_core/mz_core.dart';
import 'package:http/http.dart' as http;

class SearchScreen extends StatefulWidget {
  const SearchScreen({super.key});

  @override
  State<SearchScreen> createState() => _SearchScreenState();
}

class _SearchScreenState extends State<SearchScreen> {
  final _results = ListenableList<String>();

  @override
  void initState() {
    super.initState();
    _results.addListener(() => setState(() {}));
  }

  @override
  void dispose() {
    Debouncer.cancel('search');
    _results.dispose();
    super.dispose();
  }

  Future<void> _search(String query) async {
    if (query.isEmpty) {
      _results.clear();
      return;
    }

    final response = await http.get(
      Uri.parse('https://api.example.com/search?q=$query'),
    );

    if (response.statusCode == 200) {
      _results
        ..clear()
        ..addAll(parseResults(response.body));
    }
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(title: const Text('Search')),
      body: Column(
        children: [
          Padding(
            padding: const EdgeInsets.all(16),
            child: TextField(
              onChanged: (query) {
                Debouncer.debounce(
                  'search',
                  const Duration(milliseconds: 500),
                  () => _search(query),
                );
              },
              decoration: const InputDecoration(
                hintText: 'Search...',
                prefixIcon: Icon(Icons.search),
              ),
            ),
          ),
          Expanded(
            child: ListView.builder(
              itemCount: _results.length,
              itemBuilder: (context, index) {
                return ListTile(title: Text(_results[index]));
              },
            ),
          ),
        ],
      ),
    );
  }
}

Example 2: Multi-Controller State #

Complete example with multiple controllers:

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

class UserController with Controller {
  User? _user;
  User? get user => _user;

  Future<void> login(String email, String password) async {
    _user = await authenticateUser(email, password);
    notifyListeners();
  }

  void logout() {
    _user = null;
    notifyListeners();
  }
}

class SettingsController with Controller {
  Settings _settings = Settings.defaults();
  Settings get settings => _settings;

  void updateTheme(ThemeMode mode) {
    _settings = _settings.copyWith(themeMode: mode);
    notifyListeners();
  }
}

class App extends StatefulWidget {
  const App({super.key});

  @override
  State<App> createState() => _AppState();
}

class _AppState extends State<App> {
  final _userController = UserController();
  final _settingsController = SettingsController();

  @override
  void dispose() {
    _userController.dispose();
    _settingsController.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return ControllerProvider<UserController>(
      controller: _userController,
      child: ControllerProvider<SettingsController>(
        controller: _settingsController,
        child: ControllerBuilder<SettingsController>(
          controller: _settingsController,
          builder: (context, ctrl) {
            return MaterialApp(
              themeMode: ctrl.settings.themeMode,
              home: const HomeScreen(),
            );
          },
        ),
      ),
    );
  }
}

Testing #

mz_core is fully tested with comprehensive test coverage:

• Unit tests for all utilities
• Widget tests for Flutter integrations
• Integration tests for complex scenarios

Run tests:

flutter test

Requirements #

• Flutter: >=3.38.0
• Dart: >=3.0.0 (included with Flutter)

Contributing #

Contributions are welcome! Please:

1. Read the contribution guidelines
2. Fork the repository
3. Create a feature branch
4. Write tests for new features
5. Ensure all tests pass
6. Submit a pull request

License #

This package is released under the MIT License.

Credits #

Developed and maintained by Pankaj Koirala.

Support #

• Issues: GitHub Issues
• Discussions: GitHub Discussions
• Repository: GitHub

Related Packages #

• provider - State management
• riverpod - Advanced state management
• logger - Logging
• rxdart - Reactive extensions

Changelog #

See CHANGELOG.md for version history.