bloc_state_gen

A powerful Dart package that generates convenient extensions for BLoC/Cubit state classes, offering pattern matching and logging capabilities through simple annotations. Now supports both traditional and inline state class definitions!

Features

🎯 Pattern Matching

• match: Complete state pattern matching requiring all cases to be handled
• matchSome: Partial pattern matching with default case handling
• Compile-time type safety

📝 Logging

• Built-in state logging functionality
• Debug-friendly state information

🎨 Flexible State Definition

• Support for both traditional and inline state class definitions
• Automatic state class detection from Bloc/Cubit generic types
• Works with both Bloc and Cubit patterns

Installation

1. Add bloc_state_gen to your pubspec.yaml:

   dependencies:
     bloc_state_gen: ^latest_version
   
   dev_dependencies:
     build_runner: ^latest_version

2. Update your main cubit class to include the generated file and add annotation @BlocStateGen()

   import 'package:flutter_bloc/flutter_bloc.dart';
   import 'package:bloc_state_gen/bloc_state_gen.dart';
   
   part 'search_state.dart';
   part 'search_cubit.s.dart';
   
   @BlocStateGen()
   class SearchCubit extends Cubit<SearchState> {
     SearchCubit() : super(const SearchInitial());
   }

3. Run the code generator:

   flutter pub run build_runner build

4. Ignore generated .s.dart files in version control by adding the following to your .gitignore:

   # Ignore generated files
   *.s.dart

Usage

2. Run the code generator:

   flutter pub run build_runner build

Feature Usage

1. match - Complete Pattern Matching

Requires handling all possible states:

Widget buildStateWidget(SearchState state) {
   return state.match(
      searchInitial: () => const StartSearch(),
      searching: (query) => const CircularProgressIndicator(),
      searchResults: (query, results) => DisplayList(items: results),
      noResults: (query) => NoResultsWidget(query: query),
      searchError: (message, query) => ErrorMessage(message: message),
   );
}

2. matchSome - Partial Pattern Matching

Handle specific states with a default case:

String getDisplayText(SearchState state) {
   return state.matchSome(
      searchResults: (query, results) => 'Found ${results.length} results for: $query',
      searchError: (message, query) => 'Error${query != null ? " for $query" : ""}: $message',
      orElse: () => 'Idle...',
   );
}

3. log - State Logging

Print state information for debugging:

void debugState(CounterState state) {
   print(state.log());  // Outputs formatted state information
}

Customizing Generation

You can selectively enable/disable features using the @BlocStateGen annotation:

@BlocStateGen(
   match: true,      // Enable complete pattern matching
   matchSome: true,  // Enable partial pattern matching
   log: true,        // Enable logging functionality
)
class SearchCubit extends Cubit<SearchState> {
   SearchCubit() : super(const SearchInitial());
}

Best Practices

1. Complete Pattern Matching

   • Use match when you need to handle all possible states
   • Ensures no state is accidentally forgotten
   • Provides compile-time safety

2. Partial Pattern Matching

   • Use matchSome when you only need to handle specific states
   • Always provide a meaningful orElse case
   • Useful for selective state handling

3. Logging

   • Enable logging during development for better debugging
   • Use in conjunction with Flutter's debug mode:

if (kDebugMode) {
print(state.log());
}

Example Project

For a complete working example, check out our example project demonstrating:

• State class definition
• Extension generation
• Usage of all three core features
• Integration with Flutter UI

License

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