vscode-instantiation

A dependency injection framework extracted from the VSCode source code with test coverage.

Usage

import { createDecorator, getSingletonServiceDescriptors, InstantiationService, registerSingleton, ServiceCollection, SyncDescriptor } from 'vscode-instantiation'

const ILogService = createDecorator<ILogService>('logService')

interface ILogService {
  readonly _serviceBrand: undefined
  log: (message: string) => void
}

class LogService implements ILogService {
  declare readonly _serviceBrand: undefined
  log(message: string): void {
    console.log(message)
  }
}

const IHelloService = createDecorator<IHelloService>('helloService')
interface IHelloService {
  readonly _serviceBrand: undefined
  hello: () => void
}
class HelloService implements IHelloService {
  declare readonly _serviceBrand: undefined
  constructor(private name: string) {

  }

  hello(): void {
    console.log('helle', this.name)
  }
}

const IOneHelloService = createDecorator<IOneHelloService>('OneHelloService')
interface IOneHelloService {
  readonly _serviceBrand: undefined
  hello: () => void
}
class OneHelloService implements IOneHelloService {
  declare readonly _serviceBrand: undefined
  constructor() {

  }

  hello(): void {
    console.log('helle, OneHelloService')
  }
}

registerSingleton(IOneHelloService, new SyncDescriptor(OneHelloService))

const IMainService = createDecorator<IMainService>('mainService')

interface IMainService {
  readonly _serviceBrand: undefined
  name: string
  add: (a: number, b: number) => number
}

class MainService implements IMainService {
  declare readonly _serviceBrand: undefined
  name = 'mainService'
  constructor(
    private a: number,
    private b: number,
    @ILogService private logService: ILogService,
    @IHelloService private helloService: IHelloService,
    @IOneHelloService private oneHelloService: IOneHelloService
  ) {
    this.logService.log('I am mainService')
  }

  add() {
    return this.a + this.b
  }

  print() {
    this.helloService.hello()
    this.oneHelloService?.hello()
    this.logService.log(`${this.name} sum: ${this.add()}`)
  }
}

const services = new ServiceCollection()

services.set(ILogService, new SyncDescriptor(LogService))
services.set(IHelloService, new SyncDescriptor(HelloService, ['SyncDescriptor'], true))

const singletonServices = getSingletonServiceDescriptors()
// eslint-disable-next-line prefer-const
for (let [id, descriptor] of singletonServices) {
  services.set(id, descriptor)
}

const instantiationService = new InstantiationService(services, true)

const mainService = instantiationService.createInstance(MainService, 2, 4)

mainService.print()

// output:
// I am mainService
// helle SyncDescriptor
// helle, OneHelloService
// mainService sum: 6