Extending the prototypes makes sense - I guess I was thrown off because I tried entering
Creep.prototypein the Screeps console, and I would seeError: This creep doesn't exist yet. I guess trying to "print" the prototype somehow tries to instantiate a Creep
This really threw me for a bit! You seem to have found the answer although you may not realise it so it's probably worth explaining exactly what's going on here!
Accessing Creep.prototype doesn't create anything. What's actually happening here is that the console calls .toString() on the object (e.g. Creep.prototype.toString()). When you call creep1.toString() it walks up the prototype chain and ends up calling Creep.prototype.toString(), but the this context is still creep1. If you call Creep.prototype.toString() directly, the this context is Creep.prototype. The toString() function tries to get this.name, but it's a getter, and it throws an error if the object doesn't have this.id.
This should work:
> !! Creep.prototype
true
Do you mean serializing them to
Memory, or is there another "heap" that offers some persistence? I was under the impression from reading the documentation that global state is reset every tick. Is this a change with the introduction of isolated VMs? Is it as simple as using a global object/array?var cached_creeps = {}; module.exports.loop = { if (!cached_creeps) { cached_creeps = [new MyCreep(Game.creeps.john_galt))]; } cached_creeps[0].say("I am " + cached_creeps[0].name); }
Yes that's exactly it. There are basically 3 kinds of memory in screeps:
- Game objects (e.g. Creep, Room, etc). These are only valid for one tick
- The heap - that is, global variables or module scoped variables as in your example. These will last until a "global reset", which happens somewhat randomly depending on server load, but is generally a few hundred ticks or so. A global reset will also occur when you update your code.
Memory(includingcreep.memory,room.memory, etc). This is actually a bit of a misnomer. It's a flat JSON structure, so it's more like storing it on disk. Only cleared if you respawn.
I find it quite useful to use game objects to cache values that are only valid in the current tick. For example, I do things like this a lot:
Room.prototype.getRepairTargets = function () {
if (! this._repairTargets) {
this._repairTargets = this.find(FIND_MY_STRUCTURES, {
filter: struct => struct.hits < struct.hitsMax,
})
}
return this._repairTargets;
};
That way I can call this.room.getRepairTargets() on several different creeps but it will only call find once each tick.
