example.ts

type ConstructorOf<TObject> = new (...input: any[]) => TObject;

class User { readonly name: string = 'Foo'; }

type HasGetName = { readonly getName: () => string; };

const getName = <TUser extends ConstructorOf<User>>(Base: TUser) => {
  return class extends Base implements HasGetName {
    public getName() { return this.name; }
  };
};

const createUser = <TUser>(methods: Function[]): TUser & User => {
  let UserConstructor: any = User;
  methods.forEach(method => (UserConstructor = method(UserConstructor)));
  return new UserConstructor();
};


const user1 = createUser<HasGetName>([getName]);
alert(user1.getName());

// How infer the `HasGetName` from the `getName` argument? So the user
// don't have to pass the generic? 

const user2 = createUser([getName]);
alert(user2.getName()); // error: Property 'getName' does not exist on type 'User'