Description:

spread

Spread Library #
Easily manage and observe the state of your Flutter applications.
Overview #
The Spread library offers a simplified way of managing state within Flutter applications. With the use of entities, subscribers, and state emitters, developers can easily store, observe, and manipulate states without the usual boilerplate.
Features #

State Management: Store state data using identifiers, types, or entities. It's like a Key-Value map with observable events.
Spread Widget: Update UI when receive a state update.
Observers: Subscribe to specific state changes and react accordingly.
State Emitters: a Mixin to Emit state changes based on types, names, or entities.
Use Cases: Abstracted business or domain logic encapsulation with the UseCase class.
Entities: Subscribe UI changes to a specific object instance identified by Type and ID.

Getting Started #
Installation
Include the library in your pubspec.yaml:

dependencies:
spread: ^0.0.8
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Then run:

pub get
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Basic Usage
Define a entity state and create a Spread widget subscribed to that entity with conditional build.
import 'package:spread/spread.dart';

class User implements Entity {
final String id;
final String name;
final List<UserPost> posts = List.empty(growable: true);

User({required this.id, required this.name});

@override
String get entityId => id;
}

class UserItem extends StatelessWidget {
final User user;

const UserItem({super.key, required this.user});

@override
Widget build(BuildContext context) {
return Spread<User>(
entity: user,
stateCondition: (User? entity) => entity!.posts.length.isEven,
builder: (BuildContext context, User? entity) {
return Text('- posts: ${entity!.posts.length.toString()}');
});
}
}
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Define a typed entity and Create a Spread Widget subscribed to inherited type states.
import 'user.dart';

abstract class UsersState {}

class LoadingUsers extends UsersState {}

class LoadedUsersSuccess extends UsersState {
final List<User> users;

LoadedUsersSuccess({required this.users});
}

class LoadedUsersFail extends UsersState {
final Object? error;
final StackTrace? stackTrace;

LoadedUsersFail({required this.error, required this.stackTrace});
}

class UsersPage extends StatelessWidget {
@override
Widget build(BuildContext context) =>
Spread<UsersState>(builder: (BuildContext context, UsersState? state) {
if (state == null) {
return _loading();
} else {
switch (state.runtimeType) {
case LoadedUsersSuccess:
{
return _userList(context, state as LoadedUsersSuccess);
}
case LoadedUsersFail:
{
return _fail(context, state as LoadedUsersFail);
}
case LoadingUsers:
default:
{
return _loading();
}
}
}
});
Widget _loading() => const Center(child: CircularProgressIndicator());
}
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Create a Spread widget subscribed to a enum state change:

enum AppState { users, posts }

class HomePage extends StatelessWidget {

@override
Widget build(BuildContext context) {
return Spread<AppState>(
builder: _homeBody,
);
}

Widget _homeBody(BuildContext context, AppState? state) {
switch (state) {
case AppState.posts:
{
return PostsPage();
}
case AppState.users:
default:
{
return UsersPage();
}
}
}
}
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Emitting state:
Using the StateEmitter mixin:
import 'package:spread/spread.dart';

class UserManager with StateEmitter {

void updateUser(User user) {
emitEntity<User>(user);
}
}
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Observing state:
Extend from the SpreadObserver:
import 'package:spread/spread.dart';

class UsersObserver extends SpreadObserver<UsersState> {

@override
onState(UsersState state) {
print("UsersObserver Observed: ${state.toString()}");
}
}
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Documentation #
Detailed documentation is available in the source code.
Contributing #
Contributions, issues, and feature requests are welcome! See our contribution guidelines for more information.
License #
This project is licensed under the BSD License. See the LICENSE file for details.

License

For personal and professional use. You cannot resell or redistribute these repositories in their original state.

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