contribution-design-pattern

A design solution to deal with decoupling features from entry-points component like app-bar, sidebar and bottom-navigation-bar.

Entry-point

• bottom navigation bar

Features owned by a team

• profile - team
• home - team

The Contribution components

IContribution

• The base component that encapsulate the Contribution information.

abstract class IContribution {
  String get contributionId;
  bool get isEnabled;
}

IBottomNavigationBarContribution

• A component that extends IContribution and encapsulate specific contribution

abstract class IBottomNavigationBarContribution implements IContribution {
  BottomNavigationBarContributionData get state;
  Widget view(BuildContext context);
}

BottomNavigationBarContributionData

• The Component that encapsulate the state of the contribution.

class BottomNavigationBarContributionData {
  final String label;
  final IconData icon;
  const BottomNavigationBarContributionData({
    required this.label,
    required this.icon,
  });
}

ContributionRegistry

• The component that encapsulate the responsibility of registering contributions.

class ContributionRegistry {
  List<IContribution> get contributions => [
        //add contributions [we can use DI to avoid cycle-dependency reference]
        ProfileBottomNavigationBarContribution(),
        HomeBottomNavigationBarContribution()
      ];
}

ContributionManager

• The component that encapsulate the responsibility of providing the right contributions to the consumers.

class ContributionManager<T extends IContribution> {
  final ContributionRegistry _registry = ContributionRegistry();
  List<T> get contributions {
    final list = _registry.contributions.whereType<T>();

    return list.where((element) => element.isEnabled).toList();
  }
}

---

Profile Team Contribution

class ProfileBottomNavigationBarContribution
    implements IBottomNavigationBarContribution {
  @override
  String get contributionId => 'profile-bottom-navigationBar-contribution';

  @override
  bool get isEnabled => true;

  @override
  Widget view(BuildContext context) {
    return const Text("Profile-Screen");
  }

  @override
  BottomNavigationBarContributionData get state =>
      const BottomNavigationBarContributionData(
        label: "Profile",
        icon: Icons.person,
      );
}

Home Team Contribution

class HomeBottomNavigationBarContribution
    implements IBottomNavigationBarContribution {
  @override
  String get contributionId => 'Home-BottomNavigationBar-Contribution';

  @override
  bool get isEnabled => true;

  @override
  Widget view(BuildContext context) {
    return const Text("Home-Screen");
  }

  @override
  BottomNavigationBarContributionData get state =>
      const BottomNavigationBarContributionData(
        icon: Icons.home,
        label: "Home",
      );
}