wiretap

What is wiretap?#

wiretap is a extremely lightweight, type-safe dependency injection library for Dart. It uses declaritive typed keys to define injectable values and providers to configure how values are resolved. You compose a WiretapContext to supply and override dependencies.

Highlights#

• Zero dependencies*, minimal runtime cost
• Strong typing with generics
• Declarative defaults via tokens
• Protection against circular dependencies
• Predictable overrides and ordering
• Works in pure Dart and Flutter

*While wiretap would like to use no dependencies, the official meta package is still required to provide analyzer feedback. This is the only dependency in use though.

Getting Started#

Installation#

Add the package to your pubspec.yaml by running dart pub add wiretap or flutter pub add wiretap.

First steps#

Define tokens, create a context, and resolve values.

import 'package:wiretap/wiretap.dart';

final configToken = createValueToken(Config(apiUrl: 'https://api.example.com'));
final httpClientToken = createToken((_) => HttpClient());
final apiServiceToken = createToken((inject) =>
  ApiService(inject(httpClientToken), inject(configToken))
);

final context = WiretapContext();
final apiService = context.inject(apiServiceToken);

Overriding values#

Override dependencies per environment or test.

final testContext = WiretapContext(providers: [
  httpClientToken.provideOverride((_) => MockHttpClient()),
  configToken.provideOverride((_) => TestConfig()),
]);

final testApiService = testContext.inject(apiServiceToken);

Collections#

Aggregate multiple values of the same type. This can be used to provide implementations of the same interface:

final pluginToken = provideCollection<Plugin>();

final context = WiretapContext(providers: [
  pluginToken.provideAdditional((_) => [AuthPlugin(), LoggingPlugin()]),
  pluginToken.provideAdditional((_) => [MetricsPlugin()]),
]);

final plugins = context.inject(pluginToken);

Next: Learn the building blocks in Core Concepts.