ᶘ ᵒᴥᵒᶅ
SealedCodegen - 'when' operator generator for @sealed classes
Getting started
- Add these dependencies
dev_dependencies:
build_runner: ^1.0.0
sealed_generator: 1.0.1- Mark any class you want with @sealed annotation (meta: ^1.1.7) and add part '.g.dart' to the header of you file
import 'package:meta/meta.dart';
part 'result.g.dart';
@sealed
class Result<T> with SealedResult<T> {}
class Success<T> extends Result<T> {
T value;
Success(this.value);
}- run:
flutter packages pub run build_runner buildGenerator will create a class OriginalClassNameSealed for you to use
class SealedResult<T> {
R when<R>({
@required R Function(Success<T>) success,
@required R Function(Failure<T>) failure,
}) {
if (this is Success<T>) {
return success(this as Success<T>);
}
if (this is Failure<T>) {
return failure(this as Failure<T>);
}
throw new Exception(
'If you got here, probably you forgot to regenerate the classes? Try running flutter packages pub run build_runner build');
}
}- Add with(or extends) to your sealed class, for e.g. class Result extends(with) ResultSealed
Using
Just create an instance of you sealed class and call when on it, for example:
var resultWidget = result.when(
success: (event) => Text(event.value),
failure: (event) => Text("Failure"),
idle: (event) => Text("idle"),
);And that's it, you are ready to use sealed classses with some sort of when
It is a very early version of the library, mostly a proof of concept, so contributions are highly welcomed