Use-In-Case Interactor Library

This package contains the implementation required to add interactors to your project.

Simple Usage

You can read about the usage in many examples inside the examples folder. Here's a quick example on how to get started:

import 'package:use_in_case/use_in_case.dart';

final class Square extends PRInteractor<double, double> {
  const Square();

  @override
  Future<double> execute(double parameter) async {
    return parameter * parameter;
  }
}

void main() async {
  const square = Square();
  final result = await square(11).get();
  print(result);
}

It's also possible to receive information about the workflow of our invocation.

/// ...
/// Definition on DownloadFileInteractor class
/// ...

void main() async {
  const downloadFile = DownloadFileInteractor();
  final stopwatch = Stopwatch();

  await downloadFile((
    sourceUri: Uri.parse('https://www.my_website.com'),
    destinationPath: 'downloads/my_website_data.txt',
  ))
  .timeout(const Duration(seconds: 30))
  .receiveBusyState((isBusy) {
    if (isBusy) {
      stopwatch.start();
    } else {
      stopwatch.stop();
    }
  })
  .onResult((data) => print('Downloading succeeded after ${stopwatch.elapsed} with $data'),)
  .onException((exception) => print('Downloading failed after ${stopwatch.elapsed} due to $exception'))
  .run();
}

This example shows an example implementation of a ParameterizedResultInteractor / PRInteractor. The first generic type returns the parameter of execute, the second defines the result/return type.

Modifiers usage

This library provides the ability to add highly customizable modifiers. There are some pre-defined modifiers such as timeout or busy state. More information on these modifiers can be read in their corresponding examples.

// ...

void main() async {
  const square = Square();
  final result = await square(11)
      .timeout(
        const Duration(seconds: 5),
        'Timeout because the computation took longer than 5 seconds.',
      )
      .receiveBusyState(
        (isBusy) => print('${isBusy ? 'start' : 'stop'} at ${DateTime.now()}'),
      )
      .get();

  print(result);
}

Writing custom modifiers

Due to the limitations of my few implementations of modifiers provided by the library, i've designed the API publically extendable. For more details you may want to take a look into the implemenation of timeout or busy state modifiers.

You can write your own modifier as follows:

final class CustomModifier<Parameter, Result>
    extends ChainedModifier<Parameter, Result> {
  const CustomModifier(super._modifier);

  @override
  EventHandler<Parameter, Result> buildEventHandler() {
    return super.buildEventHandler().after((details, event) {
      event.whenOrNull(
        onStart: (parameter) {
          print('${details.calleName} started with $parameter -->');
        },
        onResult: (result) =>
            print('<-- ${details.calleName} succeeded with $result'),
        onException: (exception) =>
            print('<-- ${details.calleName} failed with $exception'),
      );
    });
  }
}

// ...

void main() async {
    const interactor = // ...
    final result = await interactor()
        .modifier((modifier) => CustomModifier(modifier)).get();

    print(result);
}

Note that this api will definitely change in future!