Boar: A Lightweight Service Locator for Dart

Boar is a lightweight and simple service locator designed for managing both synchronous and asynchronous services in Dart applications. It provides a clean API for registering and retrieving services, supporting lazy initialization for asynchronous services and automatic caching after initialization.

Features

• Register and retrieve synchronous services.
• Register and retrieve asynchronous services with lazy initialization.
• Automatically cache initialized services.
• Simple, intuitive API for managing dependencies.

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Installation

To add boar_locator to your project, include the following dependency in your pubspec.yaml file:

dependencies:
  boar_locator: ^latest_version

Then, import the library in your Dart code:

import 'package:boar_locator/boar_locator.dart';

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Usage

1. Creating a BoarLocator Instance

First, create an instance of BoarLocator:

final locator = BoarLocator();

2. Registering and Retrieving Synchronous Services

You can register and retrieve synchronous services with the instance of BoarLocator.

class ApiService {
  final String baseUrl;
  ApiService(this.baseUrl);
}

void main() {
  final locator = BoarLocator();

  // Registering a synchronous service
  locator.register(ApiService("https://api.example.com"));

  // Retrieving the service
  final apiService = locator.get<ApiService>();
  print(apiService.baseUrl); // Output: https://api.example.com
}

Unregistering Services

You can unregister a service by its type using locator.unregister().

locator.unregister<ApiService>();

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3. Registering and Retrieving Asynchronous Services

Asynchronous services are registered using an initializer function and are only initialized when requested.

class DatabaseService {
  Future<void> initialize() async {
    await Future.delayed(Duration(seconds: 2));
  }
}

void main() async {
  final locator = BoarLocator();

  // Registering an asynchronous service
  locator.registerAsync<DatabaseService>(() async {
    final dbService = DatabaseService();
    await dbService.initialize();
    return dbService;
  });

  // Retrieving the asynchronous service
  final dbService = await locator.getAsync<DatabaseService>();
  print("DatabaseService initialized");
}

Optional Retrieval of Services

To safely retrieve services without throwing errors when they are not registered, use maybeGet() or maybeGetAsync().

void main() async {
  final locator = BoarLocator();

  // Synchronous service retrieval (returns null if not found)
  final apiService = locator.maybeGet<ApiService>();
  if (apiService != null) {
    print(apiService.baseUrl);
  }

  // Asynchronous service retrieval (returns null if not found)
  final dbService = await locator.maybeGetAsync<DatabaseService>();
  if (dbService != null) {
    print("DatabaseService is ready");
  }
}

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API Reference

BoarLocator Instance Methods

Method	Description
register<T>(object)	Registers a synchronous service of type T.
registerAsync<T>(init)	Registers an asynchronous service of type T with an initializer function.
get<T>()	Retrieves a registered synchronous service of type T. Throws an error if not registered.
maybeGet<T>()	Retrieves a registered synchronous service of type T, or null if not registered.
getAsync<T>()	Retrieves a registered asynchronous service of type T. Throws an error if not registered.
maybeGetAsync<T>()	Retrieves a registered asynchronous service of type T, or null if not registered.
unregister<T>()	Unregisters a service of type T.

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Examples

Complete Example: Managing Multiple Services

class ApiService {
  final String baseUrl;
  ApiService(this.baseUrl);
}

class AuthService {
  final String token;
  AuthService(this.token);
}

void main() async {
  final locator = BoarLocator();

  // Register services
  locator.register(ApiService("https://api.example.com"));
  locator.registerAsync<AuthService>(() async {
    await Future.delayed(Duration(seconds: 1));
    return AuthService("secure-token");
  });

  // Retrieve synchronous service
  final apiService = locator.get<ApiService>();
  print(apiService.baseUrl); // Output: https://api.example.com

  // Retrieve asynchronous service
  final authService = await locator.getAsync<AuthService>();
  print(authService.token); // Output: secure-token
}

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