Regarding your first problem: It seems that you are missing a closing parenthesis. creep.attack(hostile[0] == ERR_NOT_IN_RANGE should be creep.attack(hostile[0]) == ERR_NOT_IN_RANGE.

Create a RoomPosition object like this: const buildPos = new RoomPosition(pos.x + x, pos.y + y, pos.roomName);

@adeptofnone said in Id<T>:

OK, let one rephrase one's question. Imagine one was storing a bunch of id-s, let's say for structures to be maintained, and imagine that this list would include walls and ramparts.
How would one go about invoking the magicks of getObjectById of this list w/o incurring the wrath of tslint (pbuh)?

The T in Id<T> can be a union type. So you can do something like:

let id: Id<StructureWall | StructureRampart>;
let wallOrRampart: StructureWall | StructureRampart | null = Game.getObjectById(id);

You can read more about union types here: https://www.typescriptlang.org/docs/handbook/unions-and-intersections.html