Booked Utils

A set of practical utilities for building Flutter apps faster: typed builders, wrappers for common patterns (ValueNotifier, StreamController), stream extensions, and chunked transformations.

Features

• Typed Widget Builders (CallbackWidgetBuilder)
• Reactive Wrappers & Listeners for ValueNotifier and StreamController
• Stream Extensions (e.g., doOnFirst)
• Chunked List Stream Transformer
• Navigation & Route Guards (BlocPopBuilder)

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Installation

Add to your pubspec.yaml:

dependencies:
  booked_utils: ^<latest_version>

Import in your Dart files:

import 'package:booked_utils/booked_utils.dart';

Note: BlocPopBuilder requires flutter_bloc in your app. Add it to your pubspec.yaml if you don't already use it.

dependencies:
  flutter_bloc: ^<latest_version>

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Contents

1. CallbackWidgetBuilder<T>

typedef CallbackWidgetBuilder<T> = Widget Function(T value);

A generic typedef for widget builders that take a value of type T.

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2. ValueNotifierWrapper<T>

ValueNotifierWrapper<int>(
  initialValue: 0,
  onChange: (value) => print('Value changed: $value'),
  child: (notifier) => ValueListenableBuilder<int>(
    valueListenable: notifier,
    builder: (context, value, _) => Text('Value: $value'),
  ),
)

Wraps a ValueNotifier for local, reactive state. Automatically disposes the notifier and can notify about changes.

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3. ValueNotifierListener<T>

final counter = ValueNotifier<int>(0);

ValueNotifierListener<int>(
  notifier: counter,
  onChange: (value) => debugPrint('Counter: $value'),
  child: const Text('Static child'),
)

Listens to a ValueNotifier and calls a callback on changes without rebuilding the child. Ideal for side effects such as snackbars, animations, or logging.

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4. StreamControllerWrapper<T>

StreamControllerWrapper<String>(
  child: (controller) => StreamBuilder<String>(
    stream: controller.stream,
    builder: (context, snapshot) => Text(snapshot.data ?? ''),
  ),
)

Manages the lifecycle of a StreamController and exposes it to a widget subtree.

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5. ChunkTransformer<T>

final chunkedStream = Stream.value(List.generate(10000, (i) => i))
  .transform(const ChunkTransformer<int>(chunkSize: 1024));
await for (final chunk in chunkedStream) {
  print('Chunk size: ${chunk.length}');
}

A StreamTransformer that splits large incoming lists into fixed-size chunks. Useful for chunked uploads, network transfers, or file operations.

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6. DoOnFirstEvent<T> Extension

Stream<int>.fromIterable([1, 2, 3])
  .doOnFirst((first) async => print('First event: $first'))
  .listen(print); // Prints: First event: 1, then 1, 2, 3

Allows performing an action (sync or async) on the first event of a stream, for initialization or logging.

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7. BlocPopBuilder<B, S>

BlocPopBuilder<MyBloc, MyState>(
  bloc: context.read<MyBloc>(),
  // Return `true` to BLOCK pop, `false` to ALLOW pop
  blockWhen: (state) => state is SavingState,
  child: const MyFormScreen(),
)

A widget that controls back navigation based on BLoC/Cubit state using a blockWhen predicate. Internally it listens to the provided bloc and feeds a computed canPop value into PopScope, so system back gestures and buttons respect your rule.

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Why use booked_utils?

• Reduces boilerplate: No need to manually manage controllers or notifiers for simple scenarios.
• Composable patterns: Designed for local state and micro-architecture without global dependencies.
• Production-ready: Null-safe, thoroughly tested in real Flutter apps.

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API Reference

Each class and extension is documented with code samples in the source. See

• ValueNotifierWrapper
• ValueNotifierListener
• StreamControllerWrapper
• ChunkTransformer
• DoOnFirstEvent
• CallbackWidgetBuilder
• BlocPopBuilder

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License

MIT