functional_listener 4.0.0

An rx like extension methods on ValueListenable type, that lets you work with ValueNotifiers almost like with Streams

example/lib/main.dart

import 'package:flutter/material.dart';
import 'package:functiona_listerner_example/model.dart';

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'functional_listener Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
        visualDensity: VisualDensity.adaptivePlatformDensity,
      ),
      home: MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

///
/// I didn't want to use any Locator or InheritedWidget
/// in this example. In a real project I wouldn't use
/// a global variable for this.
Model? theModel = Model();

class MyHomePage extends StatefulWidget {
  MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  @override
  Widget build(BuildContext context) {
    print(theModel);
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Padding(
          padding: const EdgeInsets.all(8.0),
          child: Column(
            crossAxisAlignment: CrossAxisAlignment.stretch,
            mainAxisAlignment: MainAxisAlignment.center,
            children: [
              Text('Type any value here'),
              // SizedBox(height: 16),
              // TextField(
              //   onChanged: theModel.updateText,
              // ),
              // SizedBox(height: 16),
              // Text(
              //     'The following field displays the entered text in uppercase.\n'
              //     'It gets only updated if the user pauses its input for at lease 500ms'),
              // SizedBox(height: 16),
              // Container(
              //   decoration: BoxDecoration(
              //     border: Border.all(),
              //   ),
              //   child: Padding(
              //     padding: const EdgeInsets.all(8.0),
              //     child: ValueListenableBuilder<String>(
              //       valueListenable: theModel.debouncedUpperCaseText,
              //       builder: (context, s, _) => Text(s),
              //     ),
              //   ),
              // ),
              // SizedBox(height: 16),
              // Text(
              //   'This counter only displays even Numbers',
              //   textAlign: TextAlign.center,
              // ),
              // ValueListenableBuilder<String>(
              //   valueListenable: theModel.counterEvenValuesAsString,
              //   builder: (context, value, _) => Text(value,
              //       style: Theme.of(context).textTheme.headlineMedium,
              //       textAlign: TextAlign.center),
              // ),
              // Text(
              //   'The following field gets updated whenever one of the others changes:',
              //   textAlign: TextAlign.center,
              // ),
              // SizedBox(height: 16),
              // ValueListenableBuilder<String>(
              //   /// Simple example of `combineLatest` without an wrapper class
              //   /// because the combiner function combines both values to one single string
              //   valueListenable: theModel.debouncedUpperCaseText.combineLatest(
              //       theModel.counterEvenValuesAsString,
              //       (s1, dynamic s2) => '$s1:$s2'),
              //   builder: (context, value, _) => Text(value,
              //       style: Theme.of(context).textTheme.headlineMedium,
              //       textAlign: TextAlign.center),
              // ),
            ],
          ),
        ),
      ),
      floatingActionButton: FloatingActionButton(
        // onPressed: theModel.incrementCounter,
        onPressed: () async {
          final storage = <List<int>>[];

          void allocateMemory() {
            storage.add(List.generate(3000, (n) => n));
            if (storage.length > 1000) {
              storage.removeAt(0);
            }
          }

          theModel!.dispose();
          theModel = null;

          // _counterEvenV    for (var i = 0; i < 300; i++) {
          allocateMemory();
          await Future.delayed(const Duration(milliseconds: 1000));
          storage.clear();
          await Future.delayed(const Duration(milliseconds: 10));
          // NativeRuntime.writeHeapSnapshotToFile('dump.heapsnapshot');
        },
        tooltip: 'Increment',
        child: Icon(Icons.add),
      ), // This trailing comma makes auto-formatting nicer for build methods.
    );
  }
}