f-person/toor

Compile-time safe & easy dependency management in Dart

🌱 What is Toor

Toor makes service locators compile-time safe and easy to manage.

Table of Contents

• 🚀 Getting Started
• ✨ Toor in detail
  • Types of locators
    • Factory
    • Lazy Singleton
    • Mutable Lazy Singleton
    • Async Factory
    • Factories with parameters
  • Advanced usage
    • Resetting lazy singletons
    • Resetting all lazy singletons
    • Creating new instances of Toor
    • Registering locators with top-level functions
• 🧪 Testing with Toor

🚀 Getting Started

Define your dependencies somewhere in the project. All global and static variables are lazy by default so you shouldn't worry about consuming memory that's not used by registering stuff.

final toor = Toor.instance;

final httpClientSingleton = toor.registerLazySingleton<IHttpClient>(
  DioHttpClientImpl.new,
);

final authRepositoryFactory = toor.registerFactory<IAuthRepository>(
  () => AuthRepositoryImpl(httpClient: httpClientSingleton()),
);

After that, you can safely access your registered factories or lazy singletons:

void authenticate(String email, String password) {
  authRepositoryFactory().authenticate(email, password);
}

✨ Toor in detail

Types of locators

Toor currently supports two types of objects: factories and lazy singletons.

Factory

Factories are locators that are created on each time you get them.

Use Toor.registerFactory to create factory locators:

final toor = Toor.instance;

final authRepositoryFactory = toor.registerFactory<IAuthRepository>(
  AuthRepositoryImpl.new,
);

Lazy Singleton

Lazy singletons are locators that are created only on the first call. The object, created at the first call, will be returned every time you get it afterwards.

Use Toor.registerLazySingleton to create lazy singleton locators:

final toor = Toor.instance;

final credentialManager = toor.registerLazySingleton<ICredentialManager>(
  CredentialManagerImpl.new,
);

Mutable Lazy Singleton

In some cases you may need your singletons to be mutable (e. g. flavors). Toor has mutable singletons for that. Use Toor.registerMutableLazySingleton in order to create a lazy singleton with a mutable value. And, in order to change the value of the singleton, use put:

final toor = Toor.instance;

final appFlavor = toor.registerMutableLazySingleton(
  create: () => Flavor.dev,
);
print(appFlavor()); // Flavor.dev

appFlavor.put(Flavor.prod);

print(appFlavor()); // Flavor.prod

When calling reset on mutable singletons, the original value (from create) is assigned to them.

Additional cleanup code with onDispose

Toor allows you to pass an optional onDispose function when registering lazy singletons in order to do some clean-up (e.g. close a socket connection, unsubscribe from a stream etc). onDispose also gives you access to the current value of the singleton. In order to use it, just pass the onDispose argument when calling registerLazySingleton:

final toor = Toor.instance;

final permissionManager = toor.registerLazySingleton<IPermissionManager>(
  PermissionManagerImpl.new,
  onDispose: (manager) {
    manager.dispose();
  },
);

Async Factory

Async factories are locators that are asynchronously created each time you get them.

Use Toor.registerFactoryAsync to create async factory locators:

final toor = Toor.instance;

final dataPersisterFactory = toor.registerFactoryAsync<IDataPersister>(
  () async => SharedPreferencesDataPersister(
    sharedPreferences: await SharedPreferences.getInstance(),
  ),
);

Await the creation of your factory to obtain and use it:

final dataPersister = await dataPersisterFactory();
dataPersister.saveData('big');

Factories with parameters

You can also create factories that accept 1 or 2 parameters:

final toor = Toor.instance;

final personFactory = toor.registerFactoryWithParam<Person, String>(
  (name) => Person(name),
);

final vehicleFactory = toor.registerFactoryWithTwoParams<Vehicle, String, int>(
  (name, productionYear) => Vehicle(name, productionYear);
);

class Person {
  const Person(this.name);

  final String name;
}

class Vehicle {
  const Vehicle(this.name, this.productionYear);

  final String name;
  final int productionYear;
}

void main() {
  // Both are compile-time safe and know about the types.
  final driver = personFactory('Doc');
  final vehicle = vehicleFactory('DeLorean', 1981);
}

Async factories are also supported via registerFactoryAsyncWithParam and registerFactoryAsyncWithTwoParams.

Advanced usage

Resetting lazy singletons

You can reset lazy singletons via the reset method. This will delete the current object and create a new one on the next call.

final toor = Toor.instance;

String value = 'Initial';

final lazySingleton = toor.registerLazySingleton<String>(
  () => value,
);

// Even though we change the `value` variable here,
// `lazySingleton`s value will remain 'Initial'.
value = 'Changed';

print(lazySingleton()); // 'Initial'

// Once we reset `lazySingleton`, it's value will be 'Changed' on the next call.
lazySingleton.reset();

print(lazySingleton()); // 'Changed'

Resetting all lazy singletons

Toor lets you reset all lazy singletons at once via the reset method on its instance. This will call reset on every lazy singleton, registered with it.

final toor = Toor.instance;

String value = 'Initial';

final lazySingleton = toor.registerLazySingleton<String>(
  () => value,
);

value = 'Changed';

print(lazySingleton()); // 'Initial'

// Once we reset `toor`, all lazy singletons, registered via
// `toor.registerLazySingleton` will be reset.
toor.reset();

print(lazySingleton()); // 'Changed'

Creating new instances of Toor

You may want to create several instances of Toor, independent of each other. The Toor.instance getter will return the default instance but you don't have to use it. You can create new instances of Toor via Toor.newInstance(). You may want to do this in order to reset lazy singletons, related to a single domain (e.g. reset all singletons that hold user data on logout).

final authToor = Toor.newInstance();
final analyticsToor = Toor.newInstance();

final credentialManager = authToor.registerLazySingleton<ICredentialManager>(
  CredentialManagerImpl.new,
);

final sessionRecorder = authToor.registerLazySingleton<ISessionRecorder>(
  SessionRecorderImpl(upload: false),
);

void logout() {
  // `credentialManager` will be reset, however `sessionRecorder` won't, since
  // it's registered in `analyticsToor`, not `authToor`.
  authToor.reset();
}

Registering locators with top-level functions

Toor provides several ways to register a locator in the global toor instance:

// You can use `Toor.instance` getter and then call 
// `registerLazySingleton` or any other method on it.
final toor = Toor.instance;

final httpClientSingleton = toor.registerLazySingleton<IHttpClient>(
  DioHttpClientImpl.new,
);

// Or you can use a top-level function with the same name 
// which basically will call the method on `Toor.instance`.
final httpClientSingleton = registerLazySingleton<IHttpClient>(
  DioHttpClientImpl.new,
);

🧪 Testing with Toor

Sometimes, you need different (e.g. mock) objects to be created in tests. There are two ways to achieve that with Toor:

1. Deciding what to register based on some variables / other toor singletons (e. g. flavor):

final toor = Toor.instance;

final authManager = toor.registerLazySingleton<IAuthManager>(
  flavor.isTesting ? MockAuthManager() : AuthManagerImpl(),
);

2. Overriding registered objects via override which is available in toor_test. The override method is annotated with visibleForTesting since it's intended to be used only in tests:

// dependencies.dart
import 'package:toor/toor.dart';

final toor = Toor.instance;

final authManager = toor.registerLazySingleton<IAuthManager>(
  AuthManagerImpl.new,
);

// app_test.dart
import 'package:toor/toor_test.dart';

void main() {
  setUpAll(() {
    authManager.override(() => MockAuthManager());
  });
}