Kernel

• Core Concepts
• Customize your velvet app
  • Add a plugin
  • Add a plugin manager observer
  • Add a plugin observer
  • Add a configuration
  • Add a register callback
  • Add a boot callback
  • Add riverpod override
  • Add riverpod observer
  • Override the App Widget
  • Override the Error Widget
  • Override the Loading Widget
  • Opt out from the env loading
• Extending the Kernel

When you createVelvetApp, you are creating a VelvetKernel instance. The kernel is the heart of your application. It is responsible for managing the application lifecycle, booting plugins, and handling errors.

Core Concepts

On initialization, the kernel sets up the container and registers some core services required for the application to function like the manager, ConfigManager and PluginManager, and some classes like the Logger and EventBus.

Also register it self as as singleton in the container.

Customize your velvet app

The entire configuration of your Velvet app is done in the main.dart file chaining the methods of the VelvetKernel instance and writing some callbacks.

This is the first look of a Velvet app:

import 'package:velvet_framework/velvet_framework.dart';

void main() {
  createVelvetApp().run();
}

Add a plugin

import 'package:velvet_framework/velvet_framework.dart';

void main() {
  createVelvetApp()
    ..withPlugins((pluginManager) {
      pluginManager.add(MyPlugin());
    })
    ..run();
}

Add a plugin manager observer

import 'package:velvet_framework/velvet_framework.dart';

void main() {
  createVelvetApp()
    ..withPlugins((pluginManager) { 
      pluginManager 
        ..addManagerObserver(MyPluginManagerObserver()) 
    }) 
    ..run();
}

Add a plugin observer

import 'package:velvet_framework/velvet_framework.dart';

void main() {
  createVelvetApp()
    ..withPlugins((pluginManager) { 
      pluginManager 
        ..addPluginObserver(MyPluginObserver()) 
    }) 
    ..run();
}

Add a configuration

import 'package:velvet_framework/velvet_framework.dart';

void main() {
  createVelvetApp()
    ..withConfig((configManager) { 
      configManager.register<MyConfigContract>(MyConfig()); 
    }) 
    ..run();
}

Add a register callback

import 'package:velvet_framework/velvet_framework.dart';

void main() {
  createVelvetApp()
    ..withRegister((container) { 
      container.register<MyServiceContract>((container) => MyService()); 
    }) 
    ..run();
}

Add a boot callback

import 'package:velvet_framework/velvet_framework.dart';

void main() {
  createVelvetApp()
    ..withBoot((container) { 
      final myService = container.get<MyServiceContract>(); 
      myService.boot(); 
    }) 
    ..run();
}

Add riverpod override

import 'package:velvet_framework/velvet_framework.dart';

void main() {
  createVelvetApp()
    ..addRiverpodOverride(exampleProvider.overrideWith((ref) => 'Hello, Velvet!')) 
    ..run();
}

Add riverpod observer

import 'package:velvet_framework/velvet_framework.dart';

void main() {
  createVelvetApp()
    ..addRiverpodObserver(MyRiverpodObserver()) 
    ..run();
}

Override the App Widget

WARNING

This feature is not yet available.

Override the Error Widget

import 'package:velvet_framework/velvet_framework.dart';

void main() {
  createVelvetApp()
    ..usingError(AppKernelErrorWidget()) 
    ..run();
}

Override the Loading Widget

import 'package:velvet_framework/velvet_framework.dart';

void main() {
  createVelvetApp()
    ..usingLoading(AppKernelErrorWidget()) 
    ..run();
}

Opt out from the env loading

import 'package:velvet_framework/velvet_framework.dart';

void main() {
  createVelvetApp()
    ..optOutFromEnvLoading() 
    ..run();
}

Extending the Kernel

To provide more methods to the kernel, you can create extensions on VelvetKernelContract and use it in the main function.

Creating an extension could be useful to clean up the main function and make it more readable.

This helps to keep the main function clean and easy to read.

extension MyPluginInstaller on VelvetKernelContract {
  void installMyPlugin() {
    withPlugins((pluginManager) {
      pluginManager.add(MyPlugin());
    });
  }
}

Then, use it in the main function:

void main() {
  createVelvetApp()
    ..installMyPlugin() 
    ..run();
}