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feat(bloc_lint): add avoid_bloc_to_bloc_members 
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‎docs/src/components/lint-rules/avoid_bloc_to_bloc_members/BadSnippet.mdx‎

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import { Code } from '@astrojs/starlight/components';
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import { transformerMetaHighlight } from '@shikijs/transformers';
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<Code
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code={`
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import 'package:bloc/bloc.dart';
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import 'package:notification_bloc/notification_bloc.dart';
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enum CounterEvent { increment };
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class CounterBloc extends Bloc<CounterEvent, int> {
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// Avoid blocs as members
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final NotificationBloc _notificationBloc;
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CounterBloc(this._notificationBloc) : super(0) {
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on<CounterEvent>((event, emit) {
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emit(state + 1);
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_notificationBloc.add(NotificationEvent(message: 'Counter value incremented'));
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});
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}
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}
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`}
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lang="dart" title="counter_page.dart"
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transformers={[transformerMetaHighlight()]} class='warning' meta="{8}"
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/>

‎docs/src/components/lint-rules/avoid_bloc_to_bloc_members/GoodSnippet.astro‎

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---
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import { Code } from '@astrojs/starlight/components';
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const code = `
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import '../bloc/counter_bloc.dart';
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import '../bloc/notification_bloc.dart';
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class MyNotifier extends StatelessWidget {
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final Widget child;
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const MyNotifier({super.key, required this.child});
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@override
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Widget build(BuildContext context) {
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// Handle at the application layer
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return BlocListener<CounterBloc, CounterState>(
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listener: (context, state) {
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context.read<NotificationBloc>().add(NotificationEvent(message: 'Counter value incremented'));
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},
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child: child,
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);
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}
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}
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`;
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---
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<Code code={code} lang="dart" title="my_notifier.dart" />

‎docs/src/content/docs/lint-rules/avoid_bloc_to_bloc_members.mdx‎

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---
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title: Avoid Bloc-to-Bloc Members
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description: The avoid_bloc_to_bloc_members rule
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---
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import { Badge } from '@astrojs/starlight/components';
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import EnableRuleSnippet from '~/components/lint-rules/EnableRuleSnippet.astro';
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import BadSnippet from '~/components/lint-rules/avoid_bloc_to_bloc_members/BadSnippet.mdx';
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import GoodSnippet from '~/components/lint-rules/avoid_bloc_to_bloc_members/GoodSnippet.astro';
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<div class="badges">
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<Badge text="new" />
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<Badge text="dart" variant="note" />
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</div>
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Avoid including `Bloc`s or `Cubit`s as members of other `Bloc`s or `Cubit`s.
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## Rationale
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While passing blocs to other blocs may be error free, it creates dependencies between blocs.
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See also [Bloc-to-Bloc Communication](https://bloclibrary.dev/architecture/#bloc-to-bloc-communication)
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## Examples
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**Avoid** passing a `Bloc` or `Cubit` to the constructor of another `Bloc` or `Cubit`.
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**BAD**:
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<BadSnippet />
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**GOOD**:
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<GoodSnippet />
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## Enable
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To enable the `avoid_bloc_to_bloc_members` rule, add it to your
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`analysis_options.yaml` under `bloc` > `rules`:
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<EnableRuleSnippet name="avoid_bloc_to_bloc_members" />

‎packages/bloc_lint/README.md‎

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## All Lint Rules
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- [avoid_bloc_to_bloc_members](https://bloclibrary.dev/lint-rules/avoid_bloc_to_bloc_members)
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- [avoid_build_context_extensions](https://bloclibrary.dev/lint-rules/avoid_build_context_extensions)
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- [avoid_flutter_imports](https://bloclibrary.dev/lint-rules/avoid_flutter_imports)
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- [avoid_public_bloc_methods](https://bloclibrary.dev/lint-rules/avoid_public_bloc_methods)

‎packages/bloc_lint/lib/all.yaml‎

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bloc:
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rules:
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- avoid_bloc_to_bloc_members
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- avoid_build_context_extensions
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- avoid_flutter_imports
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- avoid_public_bloc_methods

‎packages/bloc_lint/lib/bloc_lint.dart‎

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export 'package:_fe_analyzer_shared/src/parser/formal_parameter_kind.dart'
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show FormalParameterKind;
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export 'package:_fe_analyzer_shared/src/parser/member_kind.dart'
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show MemberKind;
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export 'package:_fe_analyzer_shared/src/parser/parser.dart'
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show DeclarationKind, IdentifierContext, Listener;
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export 'package:_fe_analyzer_shared/src/scanner/token.dart'
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export 'src/linter.dart' show LintContext, Linter;
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export 'src/rules/rules.dart'
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show
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AvoidBlocToBlocMembers,
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AvoidBuildContextExtensions,
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AvoidFlutterImports,
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AvoidPublicBlocMethods,

‎packages/bloc_lint/lib/src/linter.dart‎

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/// All supported lint rules.
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final allRules = <String, LintRuleBuilder>{
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AvoidBlocToBlocMembers.rule: AvoidBlocToBlocMembers.new,
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AvoidBuildContextExtensions.rule: AvoidBuildContextExtensions.new,
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AvoidFlutterImports.rule: AvoidFlutterImports.new,
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AvoidPublicBlocMethods.rule: AvoidPublicBlocMethods.new,

‎packages/bloc_lint/lib/src/rules/avoid_bloc_to_bloc_members.dart‎

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import 'package:bloc_lint/bloc_lint.dart';
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/// {@template avoid_bloc_to_bloc_members}
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/// The avoid_bloc_to_bloc_members lint rule.
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/// {@endtemplate}
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class AvoidBlocToBlocMembers extends LintRule {
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/// {@macro avoid_bloc_to_bloc_members}
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AvoidBlocToBlocMembers([Severity? severity])
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: super(name: rule, severity: severity ?? Severity.warning);
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/// The name of the lint rule.
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static const rule = 'avoid_bloc_to_bloc_members';
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@override
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Listener? create(LintContext context) => _Listener(context);
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}
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class _Listener extends Listener {
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_Listener(this.context);
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final LintContext context;
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bool _isRelevantEnclosingClass = false;
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@override
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void beginClassDeclaration(
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Token begin,
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Token? abstractToken,
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Token? macroToken,
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Token? sealedToken,
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Token? baseToken,
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Token? interfaceToken,
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Token? finalToken,
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Token? augmentToken,
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Token? mixinToken,
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Token name,
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) {
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_isRelevantEnclosingClass = false;
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final extendz = name.next;
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if (extendz == null || extendz.kind != Keyword.EXTENDS.kind) return;
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final superclazz = extendz.next;
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if (superclazz == null) return;
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if (_isBlocLike(superclazz)) {
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_isRelevantEnclosingClass = true;
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}
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return;
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}
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@override
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void endClassFields(
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Token? abstractToken,
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Token? augmentToken,
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Token? externalToken,
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Token? staticToken,
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Token? covariantToken,
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Token? lateToken,
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Token? varFinalOrConst,
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int count,
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Token beginToken,
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Token endToken,
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) {
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if (!_isRelevantEnclosingClass) return;
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if (staticToken != null) return;
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final fieldName = _getFieldName(beginToken, endToken);
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if (!_isBlocLike(fieldName)) return;
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context.reportTokenRange(
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beginToken: beginToken,
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endToken: endToken,
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message: 'Avoid bloc or cubit members of blocs or cubits.',
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hint: 'Prefer pushing the problem into the presentation or domain layer.',
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);
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}
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@override
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void endFormalParameter(
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Token? thisKeyword,
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Token? superKeyword,
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Token? periodAfterThisOrSuper,
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Token nameToken,
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Token? initializerStart,
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Token? initializerEnd,
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FormalParameterKind kind,
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MemberKind memberKind,
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) {
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if (!_isRelevantEnclosingClass) return;
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final typeAnnotation = _getParameterTypeAnnotation(nameToken);
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if (typeAnnotation == null) return;
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if (!_isBlocLike(typeAnnotation)) return;
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context.reportTokenRange(
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beginToken: typeAnnotation,
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endToken: nameToken,
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message: 'Avoid bloc or cubit members of blocs or cubits.',
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hint: 'Prefer pushing the problem into the presentation or domain layer.',
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);
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}
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}
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bool _isBlocLike(Token token) =>
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token.lexeme.endsWith('Bloc') || token.lexeme.endsWith('Cubit');
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List<Token> _getTokens(Token begin, Token end) {
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final tokens = <Token>[];
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Token? token = begin;
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while (token != null && token != end) {
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tokens.add(token);
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token = token.next;
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}
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return tokens;
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}
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Token _getFieldName(Token begin, Token end) {
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final tokens = _getTokens(begin, end);
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final equalsIndex = tokens.indexWhere((token) => token.type == TokenType.EQ);
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if (equalsIndex != -1) return tokens.elementAt(equalsIndex).previous!;
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return end.previous!;
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}
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Token? _getParameterTypeAnnotation(Token? formalParameter) {
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final previous = formalParameter?.previous;
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if (previous?.type == TokenType.QUESTION) {
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// FooBloc? foo
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// ^^^^^^^
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return previous?.previous;
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}
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// FooBloc foo
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// ^^^^^^^
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return previous;
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}

‎packages/bloc_lint/lib/src/rules/rules.dart‎

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export 'avoid_bloc_to_bloc_members.dart';
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export 'avoid_build_context_extensions.dart';
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export 'avoid_flutter_imports.dart';
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export 'avoid_public_bloc_methods.dart';

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