Make Creeps and PowerCreeps inherit from a "Movable" class

artch

Introducing a new base class behind Creep class is a major breaking change for userspace code. Not just a breaking change, but a major breaking change, it will affect too many things (not in the engine, but in players' code). We will only consider such changes in some opt-in backward-incompatible versions of the game API, like 2.0 or something, but not in the current version.

Knightshade

With Iso-VM being a thing, this should be a viable option, no?

EDIT: Actually, would this even be a significantly breaking change? Only players who had gone into the power creep move prototype would be having problems with the change breaking, and those players would explicitly be the ones trying to fix this problem.

Not only that, was removing preboosting not a breaking change? And that was a hell of a lot more widespread than people mucking about in the power creep movement prototype.

Come to think of it, you could just as easily just point both the power creep and regular creep move commands to the prototype they're inheriting from and mark them as depreciated. That both wouldn't break anything and allow would allow people to get their code fixed.

WarInternal

@artch Due to how prototype inheritance works I don't believe this would break anything.

If we introduce a LivingEntity (choose any name) class between RoomObject and PowerCreep/Creep, the empty class by itself will change exactly nothing in the behavior. Existing properties and methods will still be inherited.

If we then move the method move to it, both classes would inherit the method as-is. The move methods on PowerCreep could be removed entirely, as instead of a hacky cross-prototype call, they'd inherit them from the LivingEntity class. And If you ever wanted to introduce a third type of movable actor you'd already have a decent base class to work with.

As for the common monkey-patching that we do that is 1) never been officially supported I thought and 2) surprise, still not broken. If you monkey-patch move on the Creep method, it will still inherit from the super class, only now it's not breaking PC because they have their own copy of move, from the LivingEntity class, and we have the option of patching that if we want to affect both.

If anybody can think of something it would break, I'm all ears.

Edit:

As for the if (!this.room) check in PC move, a prototype call can still be made but it needs to stay within it's own chain. If PC inherited from LivingEntity, something like:

PowerCreep.prototype.moveTo = register.wrapFn(function(firstArg, secondArg, opts) {
        if(!this.room) {
            return C.ERR_BUSY;
        }
        return globals.LivingEntity.prototype.moveTo.call(this, firstArg, secondArg, opts);
    });

would be acceptable, if LivingEntity were the parent class to PowerCreep.

SemperRabbit

@artch, @o4kapuk, check out this fork of the engine. I have successfully tested this with creeps with both my and an Overmind codebase for approx 160k ticks each. neither of them broke at all. I had to build it with the refact-remove-ivm branch of the driver repo, but master for everything else... @GimmeCookies said he would test PowerCreep code on it later today. so far, we have not found any breaking changes in the slightest. I would love for others to test it too (ideally including the devs), to see if there is anything to break.

Dignissi

Honestly, this idea makes a lot of sense.

@SemperRabbit has a working branch of the code, and I can't see a single thing that would break if done properly (since seamless inheritance like this is literally the point of objects)

@artch can you name a single thing that would actually break with this change?

daboross

I can think of several things which wouldn't break with this?

grabbing Creep.move with var x = Creep.prototype.move.
grabbing Creep.moveTo with var x = Creep.prototype.moveTo.
grabbing Creep.moveByPath with var x = Creep.prototype.moveByPath.
calling c.moveTo() with any arguments
replacing the Creep move prototype with Creep.prototype.move = x; and having creep movement use the new function
replacing the Creep moveByPath prototype with Creep.prototype.moveByPath = x; and having creep movement use the new function
replacing the Creep moveTo prototype with Creep.prototype.moveTo = x; and having creep movement use the new function

The only thing which would break, as far as I can tell, are:

overwriting Creep.prototype.moveTo = x; and then expecting somePowerCreep.moveTo() to use the new creep moveTo function
overwriting Creep.prototype.moveByPath = x; and then expecting somePowerCreep.moveByPath() to use the new Creep moveByPath function

Both of these things are breaking only to people who've written PowerCreep code in the time since they've been out, and both have the easily fixable solution of overwriting Moveable.moveTo / Moveable.moveByPath. There's no way this can affect idle users, even if they extensively use the prototype system.

SemperRabbit

@daboross yeah, at best, it'd be a minor breaking change... and seeing as modifying Creep.prototype.move etc affecting PowerCreep stuff is not documented in the API, no one has any right to get butt hurt about it changing. it's like if someone were to rely on the exact order of a .find(). if that changes and breaks their code, who's fault is that? Never trust anything that's not in the API...

SystemParadox

I would argue that Creep.move affecting PowerCreep.move is itself a bug. This surprised me when I encountered it and I fully expected it to be fixed at some point. Anyone relying on this behaviour is relying on a bug and should expect it to be fixed. For what it's worth, fixing this will break my code, but I still want it to be fixed.

All you need to do is publish an announcement far enough in advance that this is the plan and anyone relying on it can prepare for it by doing this:

PowerCreep.prototype.move = Creep.prototype.move;
PowerCreep.prototype.moveTo = Creep.prototype.moveTo;
PowerCreep.prototype.moveByPath = Creep.prototype.moveByPath;
PowerCreep.prototype.transfer = Creep.prototype.transfer;
PowerCreep.prototype.withdraw = Creep.prototype.withdraw;
PowerCreep.prototype.drop = Creep.prototype.drop;
PowerCreep.prototype.pickup = Creep.prototype.pickup;
PowerCreep.prototype.say = Creep.prototype.say;

For anyone who does this or isn't relying on the buggy behaviour there are no breaking changes!

Note: I would strongly suggest that all of the offending methods above should be fixed, not just the move ones, so the class should probably be called BaseCreep or something rather than Movable.

deft-code

Here is a behavior change. Object.getOwnPropertyNames(Creep.prototype) would no longer return move or moveTo.

I assumed it would break more stuff. I was surprised that Creep.prototype.move still worked the same.

I really think this is a good idea. And it fixes the bug of changes to Creep.move affecting PowerCreep.move.

SemperRabbit

Ok everyone, @ags131 very graciously set up a pServ at prtest.screepspl.us as a test with my fork/branch of engine with a BaseCreep class. He and @WarInternal already helped me identify/fix 1 error in it, and it is running pretty smoothly right now. Please spawn in and post results if you can

@artch, idk if you have any code, but you and @o4kapuk are more than welcome to spawn in too. I'd love to get feedback on what the devs think. btw, figuring out the data() call was more tricky than I thought (see the commits from today lol)

Again, everyone can take a look at my branch here: https://github.com/semperrabbit/screeps_engine/tree/BaseCreep

Davaned

@semperrabbit Thank you for taking the initiative on this Semp. This is huge. I'd like to recommend adding a FIND_MOVEABLES or something similar so there can be a unified lookup, and probably others I'm not thinking of.

How is pull handled here?

deft-code

@SemperRabbit No pull request so I'll leave code review comments here.

Use braces on all multi line if statements. That seems to be the style in the rest of the repo.

Consider breaking this up into two PRs. The first one creates the new base-creep type in the existing creep file renaming classes but otherwise not moving code around. The second one moves it all to the new file. This would be far easier to review as the unchanged functions would be nearly diff free. The second one would have tons of diffs but very little new code. The easier the PR is to review the more likely the devs will accept it.

We're still having memory problems with high room counts. I suspect the indexes are to blame. FIND_MOVEABLES is a fine idea but I would discourage a new index just concat the FIND_POWER_CREEPS and FIND_CREEPS calls. For completeness add a FIND_MY_MOVEABLES as well.

deft-code

@SemperRabbit It looks like this is branched from main. It should branch from PTR, otherwise this will force all the new Store to code to rebased (merge-hell).

SemperRabbit

its ok @deft-code, ty for the suggestions, but yeah, i guess its not happening ever. devs put their foot down, testing be damned.

SystemParadox

@artch, I have to say that in light of the recent update I am now quite confused by the decision not to do anything about this.

I would urge you to rethink your previous assertion that this would be a major breaking change. The community has put in significant effort to investigate and show that this change would actually have very minimal impact.

The strongholds update did actually contain several major breaking changes, so clearly you are willing to make changes if the benefits are clear. I think they are clear in this case. The current situation results in strange and confusing bugs and there is no advantage to keeping it this way other than some notion of backwards compatibility, which is pretty moot since this has been shown to be almost entirely backwards compatible. Additionally, it is exactly those players that would be affected who are asking for this to be changed.

artch

We will revisit this topic when we come back to Power Creeps (Operator) balance in the nearest future.