talker_bloc_effects 0.1.0

A Talker observer for BLoC lifecycle logs and bloc_effects emissions, with source-aware filtering and configurable effect output.

talker_bloc_effects

One Talker observer for standard BLoC logs and bloc_effects emissions. Each effect log includes its emitting Bloc/Cubit, when available.

Install

dependencies:
  talker_bloc_effects: ^0.1.0

Requires Flutter 3.24 or later and Dart 3.5 or later. Supports Talker 5.1.20+, bloc_effects 2.1.0+, and BLoC 9 within their respective major versions. Flutter SDK is required because bloc_effects depends on Flutter.

Connect the observer

import 'package:bloc/bloc.dart';
import 'package:talker/talker.dart';
import 'package:talker_bloc_effects/talker_bloc_effects.dart';

final talker = Talker();

void main() {
  Bloc.observer = TalkerBlocEffectsObserver(talker: talker);
  // Create your blocs/cubits and start the application here.
}

Declare packages you import directly in your application's dependencies. Install the observer before creating any Bloc, Cubit, or Effects source: these objects capture the observer at construction time.

The observer extends TalkerBlocObserver and also implements BlocWithEffectsObserver. Assign it directly to Bloc.observer; wrapping it in a standard MultiBlocObserver does not forward effect callbacks.

When talker is omitted, one instance is created and shared by all logs. Access it through observer.talker to read its history or connect a Talker screen.

Emit an effect

import 'package:bloc_effects/bloc_effects.dart';

class CounterCubit extends CubitWithEffects<int, String> {
  CounterCubit() : super(0);

  void increment() {
    emit(state + 1);
    emitEffect('Counter is $state');
  }
}

The effect appears under the bloc-effect key, for example:

CounterCubit emitted effect:
Counter is 1

BlocWithEffects and the Effects mixin are supported too. An Effects source that is not a Bloc/Cubit has a null BlocEffectLog.bloc. Null effects and repeated identical effects are logged individually.

Logging observes emission. It does not subscribe to the effect stream, replay effects, or confirm that a UI listener handled them. Effects are logged even when there are no active listeners.

Settings

Bloc.observer = TalkerBlocEffectsObserver(
  talker: talker,
  settings: const TalkerBlocLoggerSettings(
    printChanges: true,
    printCreations: true,
    printClosings: true,
  ),
  effectsSettings: TalkerBlocEffectsSettings(
    enabled: true,
    printEffectFullData: false,
    effectFilter: (bloc, effect) => bloc is CounterCubit,
  ),
);

Effect logging and full toString() messages are enabled by default. Set printEffectFullData: false to display only the runtime type. This changes the message, not the original effect retained in BlocEffectLog. Use effectFilter to exclude an effect completely. It receives a nullable source and runs before formatting; disabling logging also skips the filter and formatting.

Standard BLoC settings retain upstream defaults: events and transitions are enabled; changes, creations, and closings are disabled. Errors retain their original stack traces. Setting effectsSettings.enabled to false disables only effects. Setting settings.enabled to false disables BLoC activity and effects, but keeps error logging, matching TalkerBlocObserver.

Use talker.disable() to stop all logs and talker.enable() to resume them. Filters and effect toString() methods run synchronously; exceptions they throw propagate to the caller, as with standard Talker BLoC logging.

Titles, colors, and TalkerScreen

The effect key is registered automatically for Talker's log filters. Customize it through the same settings as other Talker logs:

final talker = Talker(
  settings: TalkerSettings(
    titles: {BlocEffectLog.logKey: 'UI effect'},
    colors: {BlocEffectLog.logKey: AnsiPen()..magenta()},
  ),
);

For a Flutter log screen, add talker_flutter to your application and use the same Talker instance. This integration does not depend on talker_flutter itself; that package may require a newer Flutter SDK.

import 'package:flutter/material.dart';
import 'package:flutter_bloc/flutter_bloc.dart';
import 'package:talker_bloc_effects/talker_bloc_effects.dart';
import 'package:talker_flutter/talker_flutter.dart';

final talker = TalkerFlutter.init();

void main() {
  Bloc.observer = TalkerBlocEffectsObserver(talker: talker);
  runApp(MaterialApp(home: TalkerScreen(talker: talker)));
}

Example

The example increments a counter, shows a Snackbar through BlocEffectListener, and logs state changes and effects to a shared Talker.

cd example
flutter pub get
flutter run -d chrome

Development

From the package root:

flutter pub get
dart format --line-length=120 --output=none --set-exit-if-changed lib test example/lib example/test
flutter analyze
flutter test
flutter pub downgrade
flutter analyze
flutter test
flutter pub upgrade
flutter pub publish --dry-run

From example, run flutter pub get, flutter analyze, flutter test, and flutter build web. CI checks the package on Flutter 3.24.0 and current stable; the stable job also tests and builds the example and validates the publication archive. No workflow publishes a release.