many_lints 0.4.0

A comprehensive collection of custom lint rules, quick fixes, and code assists for Flutter and Dart projects.

example/README.md

many_lints Examples

This directory contains example code demonstrating each lint rule provided by many_lints. Each file in lib/ corresponds to a single rule and contains code that triggers the lint.

Setup

Add to your analysis_options.yaml:

plugins:
  many_lints: ^0.3.0

All Rules

Rule	Description	Fix
always_remove_listener	Listener added but never removed in dispose()	Yes
avoid_accessing_collections_by_constant_index	Avoid accessing a collection by a constant index inside a loop	—
avoid_bloc_public_methods	Avoid declaring public members in Bloc classes	—
avoid_border_all	Prefer Border.fromBorderSide over Border.all	Yes
avoid_cascade_after_if_null	Cascade after if-null operator can produce unexpected results	Yes
avoid_conditional_hooks	Hooks called inside conditionals or loops	—
avoid_collection_equality_checks	Comparing collections with ==/!= checks reference equality	—
avoid_collection_methods_with_unrelated_types	Collection method calls with arguments unrelated to the collection's type	—
avoid_commented_out_code	Detects comments that look like commented-out code	Yes
avoid_constant_conditions	Both sides of a comparison are constants	—
avoid_constant_switches	The switch expression is a constant	—
avoid_contradictory_expressions	Contradictory comparisons in && chains	—
avoid_duplicate_cascades	Duplicate cascade sections that indicate copy-paste errors	Yes
avoid_expanded_as_spacer	Prefer Spacer over Expanded with empty child	Yes
avoid_flexible_outside_flex	Flexible/Expanded should only be inside Row/Column/Flex	—
avoid_generics_shadowing	Generic type parameter shadows a top-level declaration	Yes
avoid_incomplete_copy_with	copyWith is missing constructor parameters	Yes
avoid_incorrect_image_opacity	Use Image's opacity instead of wrapping in Opacity	Yes
avoid_map_keys_contains	Use containsKey() instead of .keys.contains()	Yes
avoid_misused_test_matchers	Incompatible matcher usage with the actual value type	—
avoid_mounted_in_setstate	Checking mounted inside setState is too late	—
avoid_notifier_constructors	Avoid constructors with logic in Notifier classes	Yes
avoid_only_rethrow	Catch clause contains only a rethrow statement	Yes
avoid_passing_bloc_to_bloc	Avoid passing a Bloc/Cubit to another Bloc/Cubit	—
avoid_passing_build_context_to_blocs	Avoid passing BuildContext to a Bloc/Cubit	—
avoid_public_notifier_properties	Public non-overridden properties in Notifier classes	—
avoid_ref_inside_state_dispose	Avoid accessing ref inside dispose()	—
avoid_ref_read_inside_build	Avoid using ref.read inside the build method	Yes
avoid_returning_widgets	Avoid returning widgets from functions/methods/getters	—
avoid_shrink_wrap_in_lists	Avoid using shrinkWrap in ListView	—
avoid_single_child_in_multi_child_widgets	Single child in multi-child widgets	—
avoid_single_field_destructuring	Avoid single-field destructuring	Yes
avoid_state_constructors	Avoid constructors with logic in State classes	Yes
avoid_throw_in_catch_block	Avoid using throw inside a catch block	Yes
avoid_unassigned_stream_subscriptions	Stream subscription not assigned to a variable	—
avoid_unnecessary_consumer_widgets	ConsumerWidget does not use WidgetRef	Yes
avoid_unnecessary_gesture_detector	GestureDetector with no event handlers	Yes
avoid_unnecessary_hook_widgets	HookWidget does not use hooks	Yes
avoid_unnecessary_overrides	Override only calls super without additional logic	Yes
avoid_unnecessary_overrides_in_state	State method override only calls super	Yes
avoid_unnecessary_setstate	Unnecessary call to setState	Yes
avoid_unnecessary_stateful_widgets	StatefulWidget with no mutable state	Yes
avoid_wrapping_in_padding	Avoid wrapping a widget in Padding when it has padding support	Yes
dispose_fields	Field not disposed in dispose()	Yes
dispose_provided_instances	Instance not disposed via ref.onDispose()	Yes
list_all_equatable_fields	Equatable subclass missing fields in props	Yes
prefer_abstract_final_static_class	Classes with only static members → abstract final	Yes
prefer_align_over_container	Use Align instead of Container with only alignment	Yes
prefer_any_or_every	.any()/.every() over .where().isEmpty/.isNotEmpty	Yes
prefer_async_callback	Use AsyncCallback instead of Future<void> Function()	Yes
prefer_bloc_extensions	Use context.read/context.watch instead of BlocProvider.of()	Yes
prefer_center_over_align	Center over Align with center alignment	Yes
prefer_class_destructuring	Use class destructuring for repeated property accesses	Yes
prefer_compute_over_isolate_run	Use compute() instead of Isolate.run()	Yes
prefer_const_border_radius	BorderRadius.all(Radius.circular()) over BorderRadius.circular()	Yes
prefer_constrained_box_over_container	ConstrainedBox over Container with only constraints	Yes
prefer_container	Nested widgets → single Container	Yes
prefer_contains	.contains() instead of .indexOf() compared to -1	Yes
prefer_correct_edge_insets_constructor	Use a simpler EdgeInsets constructor	Yes
prefer_enums_by_name	.byName() instead of .firstWhere() for enum values	Yes
prefer_equatable_mixin	EquatableMixin instead of extending Equatable	Yes
prefer_expect_later	expectLater when testing Futures	Yes
prefer_explicit_function_type	Explicit return type over bare Function	Yes
prefer_for_loop_in_children	For-loop instead of functional list building	Yes
prefer_immutable_bloc_state	Bloc state classes → @immutable	Yes
prefer_iterable_of	.of() instead of .from() for type safety	Yes
prefer_multi_bloc_provider	MultiBlocProvider instead of nested BlocProviders	Yes
prefer_overriding_parent_equality	Parent overrides ==/hashCode but subclass does not	Yes
prefer_padding_over_container	Padding over Container with only margin	Yes
prefer_return_await	Missing await on returned Future in try-catch	Yes
prefer_returning_shorthands	Dot shorthands when instance type matches return type	Yes
prefer_shorthands_with_constructors	Dot shorthands instead of explicit class instantiations	Yes
prefer_shorthands_with_enums	Dot shorthands instead of explicit enum prefixes	Yes
prefer_shorthands_with_static_fields	Dot shorthands instead of explicit class prefixes	Yes
prefer_simpler_patterns_null_check	Simpler null-check patterns	Yes
prefer_single_setstate	Merge multiple setState calls	Yes
prefer_single_widget_per_file	One public widget per file	—
prefer_sized_box_square	SizedBox.square instead of equal width/height	Yes
prefer_spacing	spacing argument instead of SizedBox	—
prefer_switch_expression	Switch expressions over switch statements	Yes
prefer_test_matchers	Matcher instead of literal value in expect()	—
prefer_text_rich	Text.rich instead of RichText	Yes
prefer_transform_over_container	Transform over Container with only transform	Yes
prefer_type_over_var	Explicit type annotation over var	Yes
prefer_use_callback	useCallback instead of inline closures in hooks	Yes
prefer_use_prefix	use prefix for custom hook functions	Yes
prefer_void_callback	VoidCallback instead of void Function()	Yes
prefer_wildcard_pattern	Wildcard pattern _ instead of Object()	Yes
proper_super_calls	super calls placed correctly in lifecycle methods	Yes
use_bloc_suffix	Bloc suffix for Bloc subclasses	Yes
use_closest_build_context	Use closest available BuildContext	Yes
use_cubit_suffix	Cubit suffix for Cubit subclasses	Yes
use_dedicated_media_query_methods	Dedicated MediaQuery methods	Yes
use_existing_destructuring	Use existing destructuring instead of direct access	Yes
use_existing_variable	Expression duplicates an existing variable's initializer	Yes
use_gap	Gap widget for spacing in multi-child widgets	Yes
use_notifier_suffix	Notifier suffix for Notifier subclasses	Yes
use_ref_and_state_synchronously	Async gap before ref/state access	Yes
use_ref_read_synchronously	ref.read stored across async gaps	Yes
use_sliver_prefix	Sliver prefix for sliver-returning widgets	Yes

Detailed Examples

avoid_single_child_in_multi_child_widgets

Multi-child widgets like Column, Row, Wrap should not be used with only a single child.

❌ Bad:

Column(
  children: [Text('Only child')],
)

✅ Good:

Text('Only child')

---

avoid_unnecessary_consumer_widgets

ConsumerWidget should only be used when the WidgetRef is actually used.

❌ Bad:

class MyWidget extends ConsumerWidget {
  @override
  Widget build(BuildContext context, WidgetRef ref) {
    // ref is never used
    return Text('Hello');
  }
}

✅ Good:

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text('Hello');
  }
}

---

avoid_unnecessary_hook_widgets

HookWidget should only be used when hooks are actually called.

❌ Bad:

class MyWidget extends HookWidget {
  @override
  Widget build(BuildContext context) {
    // No hooks called
    return Text('Hello');
  }
}

✅ Good:

class MyWidget extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return Text('Hello');
  }
}

---

prefer_align_over_container

Use Align widget instead of Container when only alignment is set.

❌ Bad:

Container(
  alignment: Alignment.topLeft,
  child: Text('Hello'),
)

✅ Good:

Align(
  alignment: Alignment.topLeft,
  child: Text('Hello'),
)

---

prefer_any_or_every

Use .any() instead of .where().isNotEmpty and .every() instead of .where().isEmpty.

❌ Bad:

final hasEven = numbers.where((n) => n.isEven).isNotEmpty;
final allPositive = numbers.where((n) => n < 0).isEmpty;

✅ Good:

final hasEven = numbers.any((n) => n.isEven);
final allPositive = numbers.every((n) => n >= 0);

---

prefer_center_over_align

Use Center widget instead of Align when alignment is center.

❌ Bad:

Align(
  alignment: Alignment.center,
  child: Text('Hello'),
)

✅ Good:

Center(
  child: Text('Hello'),
)

---

prefer_padding_over_container

Use Padding widget instead of Container when only margin is set.

❌ Bad:

Container(
  margin: EdgeInsets.all(16),
  child: Text('Hello'),
)

✅ Good:

Padding(
  padding: EdgeInsets.all(16),
  child: Text('Hello'),
)

---

use_bloc_suffix

Classes extending Bloc should have the Bloc suffix.

❌ Bad:

class CounterManager extends Bloc<CounterEvent, int> {}

✅ Good:

class CounterBloc extends Bloc<CounterEvent, int> {}

---

use_cubit_suffix

Classes extending Cubit should have the Cubit suffix.

❌ Bad:

class Counter extends Cubit<int> {}

✅ Good:

class CounterCubit extends Cubit<int> {}

---

use_dedicated_media_query_methods

Use dedicated MediaQuery methods to avoid unnecessary rebuilds.

❌ Bad:

final size = MediaQuery.of(context).size;
final padding = MediaQuery.of(context).padding;
final orientation = MediaQuery.of(context).orientation;

✅ Good:

final size = MediaQuery.sizeOf(context);
final padding = MediaQuery.paddingOf(context);
final orientation = MediaQuery.orientationOf(context);

---

use_gap

Use Gap widget instead of SizedBox or Padding for spacing in multi-child widgets.

❌ Bad:

Column(
  children: [
    Text('First'),
    SizedBox(height: 16),
    Text('Second'),
  ],
)

✅ Good:

Column(
  children: [
    Text('First'),
    Gap(16),
    Text('Second'),
  ],
)

---

use_notifier_suffix

Classes extending Notifier should have the Notifier suffix.

❌ Bad:

class CounterManager extends Notifier<int> {}

✅ Good:

class CounterNotifier extends Notifier<int> {}

---

Suppressing Diagnostics

To suppress a specific lint, use comments:

// ignore: many_lints/prefer_center_over_align
const Align(...);

// ignore_for_file: many_lints/use_bloc_suffix

More Information

See the individual example files in lib/ for complete, runnable code samples.