simply_injector 1.0.0-nullsafety.4

An easy-to-use Dependency Injection (DI) library for Dart, inspired and based on Simple Injector library. It is easily integrated with Flutter.

Simply Injector

Simply Injector is a dart package inspired and based on Simple Injector library.

It is an easy-to-use dependency injection (DI) library and is easily integrated with Flutter.

It’s easy to implement the dependency injection pattern with loosely coupled components using Simply Injector Dart Package.

Configuration

Add simply_injector to pubspec.yaml under the dependencies field.

dependencies:
  simply_injector: ^latest_version

Import

Add the following import in your library :

import 'package:simply_injector/simply_injector.dart';

Usage

Simply Injector's main type is the Container. An instance of Container is used to register mappings between each abstraction (service) and its corresponding implementation (component).

Tip: You should typically create a single Container instance for the whole application (one instance per app domain).

It's possible create an instance of Container by some ways:

var container = new SimplyInjector.Container();

or

var container = new Container();

or using a library prefix to avoid conflict with Flutter's *Container' class:

import 'package:simply_injector/simply_injector.dart' as si;
...
si.Container container = new si.Container();

The first way it's so much elegantly ;)

Example

This is the main source of complete example project at Simply Injector GitHub repository:

import 'package:simply_injector/simply_injector.dart';

import 'CancelOrder.dart';
import 'CancelOrderHandler.dart';
import 'EventPublisher.dart';
import 'FileLogger.dart';
import 'Guid.dart';
import 'IEventPublisher.dart';
import 'ILogger.dart';
import 'IOrderRepository.dart';
import 'SqlOrderRepository.dart';

main()
{
  // 1. Create a new Simple Injector container
  var container = new SimplyInjector.Container();

  // 2. Configure the container (register)
  container.register<IOrderRepository, SqlOrderRepository>( () => new SqlOrderRepository(container.get<ILogger>()));
  container.register<ILogger, FileLogger>( () => new FileLogger(), Lifestyle.Singleton );
  container.register<IEventPublisher, EventPublisher>( () => new EventPublisher(), Lifestyle.Singleton );

  container.register<CancelOrderHandler, CancelOrderHandler>(()
    => new CancelOrderHandler(
      container.get<IOrderRepository>(),
      container.get<ILogger>(),
      container.get<IEventPublisher>() 
    )
  );

  // 3. Verify your configuration
  container.verify();

  // 4. Use the container
  var handler = container.getInstance<CancelOrderHandler>();

  var args = ['0123456789'];
  var orderId = Guid.Parse(args[0]);
  var command = new CancelOrder(orderId);

  handler.Handle(command);
}