Wyr

Pronounced: wire
Wyr is a zero-crap, zero-dependency, lightweight, and typesafe dependency injection framework for TypeScript. It’s designed to be simple yet powerful, with full support for asynchronous bindings.

Features

• Typesafe: Enjoy TypeScript’s type safety when defining and retrieving dependencies.
• Async Bindings: Seamlessly handle asynchronous creation of dependencies.

Installation

To install Wyr, run:

npm install --save wyr

Basic Usage

Creating a Module and Binding Dependencies

Wyr uses modules to define bindings. Each binding has a unique key and a creator that builds the dependency.

import Wyr, { BindingKey } from 'wyr';

// Create a new module
const module = Wyr.module();

// Define binding keys for the dependencies
const userRepoKey: BindingKey<UserRepo> = Symbol('UserRepo');
const userEventEmitterKey: BindingKey<UserEventEmitter> = Symbol('UserEventEmitter');
const userServiceKey: BindingKey<UserService> = Symbol('UserService');

// Bind the UserEventEmitter
module.bind(userEventEmitterKey).to(
  Wyr.creator()(async () => {
    return new UserEventEmitter();
  })
);

// Bind the UserRepo
module.bind(userRepoKey).to(
  Wyr.creator()(async (userEventEmitter) => {
    return new UserRepo(userEventEmitter);
  })
);

// Bind the  UserService that depends on UserRepo and UserEventEmitter
module.bind(userServiceKey).to(
  Wyr.creator(userRepoKey, userEventEmitterKey)(async (userRepo, userEventEmitter) => {
    return new UserService(userRepo, userEventEmitter);
  })
);

// Create a container from the module
const container = module.asContainer();

// Retrieve multiple dependencies, including the UserService and UserEventEmitter
const [userService, userEventEmitter] = await container.get(userServiceKey, userEventEmitterKey);

// Use the UserService and UserEventEmitter
userService.performAction();

Explanation:

Binding Keys: userRepoKey, loggerKey, and userServiceKey uniquely identify each service. Creators: The UserService is created with its dependencies (UserRepo and UserEventEmitter) using the Wyr.creator(userRepoKey, userEventEmitterKey) function. Retrieving Dependencies: Multiple keys can be passed to container.get(...) to retrieve a tuple of dependencies, in this case UserService and UserEventEmitter.

Merging Modules

Sometimes it comes in handy to group multiple bindings into a module, and create a container out of multiple modules. Modules can be merged, allowing you to compose dependencies from different parts of your application.

const anotherModule = Wyr.module();
// Merge modules together
module.mergeWith(anotherModule);

and a container can be created out of multiple modules like this:

const container = Wyr.container(module1,module2,module3)

License

Wyr is licensed under the MIT License.