Type-Safe Dependency Injection Registry Pattern

abstract class ServiceToken<T> {
  readonly _type!: T;
}
 
function createToken<T>(description: string): ServiceToken<T> {
  return { description } as unknown as ServiceToken<T>;
}
 
class Container {
  private services = new Map<ServiceToken<any>, any>();
 
  register<T>(token: ServiceToken<T>, instance: T): void {
    this.services.set(token, instance);
  }
 
  resolve<T>(token: ServiceToken<T>): T {
    const instance = this.services.get(token);
    if (!instance) throw new Error('Service not registered');
    return instance as T;
  }
}
 
interface Logger { log(msg: string): void; }
const LOGGER_TOKEN = createToken<Logger>('LoggerService');
 
const container = new Container();
container.register(LOGGER_TOKEN, { log: console.log });
const logger = container.resolve(LOGGER_TOKEN);