mz_lints

Custom Dart lint rules for Flutter applications. Helps catch common mistakes with ChangeNotifier disposal, listener cleanup, and Controller lookup patterns.

Available Rules

Rule	Description	Quick Fixes
dispose_notifier	ChangeNotifier subclasses created in State must be disposed	Add dispose method, Add dispose call
remove_listener	Listeners added to Listenables must be removed in dispose	Add removeListener call
controller_listen_in_callback	Controller lookups in callbacks should use listen: false	Add 'listen: false'

Installation

Add mz_lints to your pubspec.yaml:

dev_dependencies:
  mz_lints: ^0.0.1

Then enable the plugin in your analysis_options.yaml:

# Requires Dart 3.10+ / Flutter 3.38+
plugins:
  mz_lints: ^0.0.1

Rule Details

dispose_notifier

Ensures ChangeNotifier subclasses created in StatefulWidget State classes are disposed:

• TextEditingController, ScrollController, AnimationController
• TabController, PageController, FocusNode
• ValueNotifier, and any custom ChangeNotifier subclass

BAD:

class _MyWidgetState extends State<MyWidget> {
  final _controller = TextEditingController(); // LINT: not disposed
  
  @override
  Widget build(BuildContext context) {
    return TextField(controller: _controller);
  }
}

GOOD:

class _MyWidgetState extends State<MyWidget> {
  final _controller = TextEditingController();

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }
  
  @override
  Widget build(BuildContext context) {
    return TextField(controller: _controller);
  }
}

remove_listener

Ensures listeners added in initState, didChangeDependencies, or didUpdateWidget are removed in dispose:

BAD:

class _MyWidgetState extends State<MyWidget> {
  @override
  void initState() {
    super.initState();
    widget.controller.addListener(_onChanged); // LINT: never removed
  }
  
  void _onChanged() {}
}

GOOD:

class _MyWidgetState extends State<MyWidget> {
  @override
  void initState() {
    super.initState();
    widget.controller.addListener(_onChanged);
  }

  @override
  void dispose() {
    widget.controller.removeListener(_onChanged);
    super.dispose();
  }
  
  void _onChanged() {}
}

controller_listen_in_callback

Warns when using Controller.ofType() or similar lookup methods inside event handlers without listen: false:

BAD:

void _onButtonPressed() {
  // Will cause unnecessary rebuilds
  final controller = Controller.ofType<MyController>(context);
  controller.doSomething();
}

GOOD:

void _onButtonPressed() {
  final controller = Controller.ofType<MyController>(context, listen: false);
  controller.doSomething();
}

Suppressing Rules

You can suppress rules using standard Dart ignore comments:

Suppress for entire file:

// ignore_for_file: dispose_notifier, remove_listener

class MyWidget extends StatefulWidget {
  // ...
}

Suppress for a single line:

class _MyWidgetState extends State<MyWidget> {
  // ignore: dispose_notifier
  final _controller = TextEditingController();
}

Requirements

• Dart SDK 3.10.0 or later
• Flutter 3.38.0 or later (for Flutter projects)

Related

This package is part of the mz_utils ecosystem.

License

MIT License - see the LICENSE file for details.