The State of LUA in DDA

[kevin.granade]

True to the can’t/won’t (more won’t than can’t, but can’t’s a part) and true to the Lua support being more common among closed-source projects, but the game engine goal is indeed what I’m arguing for.

That’s pretty much an impasse, I’m not interested in dda as an engine per se. I’m happy to add data-driven behavior, but only to the extent that it improves dda-the-game.

As a prototype of bindings that I would probably

That’s probably weeks to months of work you just outlined. The basic data bindings aren’t that bad, but all the querying and injection of callbacks and overrides is, and as you say, this is just a start.

I’m not sure that some 500-or-so gameplay functions would need direct checking against 10000-or-so engine-related classes and features and vice versa.

I’m not following you, what I mean is every change needs to be scrutinized for “is this going to change how any of the LUA interfaces work?”. This means that someone intimately familiar with the bindings has to review every code change. Alternately, we don’t do that, and the LUA bindings break constantly.

isn’t the Lua system already set up just to generate the bindings from plain-text entries?

That doesn’t meaningfully change anything, someone still has to manually update those text entries every time a bound method is changed. Someone still has to be watching for those changes in the stream of PRs. Someone still has to write helper methods any time an API can’t be exposed as-is.

How often do…

I don’t have numbers, but it’s enough to be problematic. Also remember that the benefit to the project is roughly 0, so I’m not willing to tolerate much.

I’m just not sure how practical it is to keep every declarative feature “in house”, especially with the breadth and scope of some changes that people might want to make.

You’re arguing for exposing an absolutely massive amount of game state via scripting bindings, that’s somehow totally fine despite a total lack of feedback about what parts are being used, but exposing actual data-driven bindings is somehow too much? The coordination and synchronization problems are present either way, the problem size is similar, the main difference is one you can implement blindly and the other requires design.
The difference is that data-driven design has been working and supplying benefits to the project incrementally. If anything, the existence of LUA bindings has been interfering with it by applying shortcuts.

[Aabbcc]

@JT1, your use of Bethesda as example really, really doesn’t work.

Not only their code is closed, they have a far larger development team, and they have an audience orders of magnitude bigger, a far more mainstream audience which is going to have a larger proportion of people willing to mod it who don’t have coding knowledge.

Besides, most people willing to mess with the script language of their games are already going to be familiar with coding, and for those that arent? There’s tutorials galore. Cata’s documentation and tutorials are flimsy and out of date enough as it is.

Lua also in no way guarantees you’ll skip the usual modding problems of multiple mods trying to touch the same thing, there’s only so much you can mitigate that, and frankly? Modifying the source code and using Git to merge changes makes it far more likely for things to be compatible than anything you could think to implement from the ground up in Lua.

[JT1]

1. Those weeks to months of work of adding external gameplay logic will be needed one way or another when work shifts to mission design and interactivity with the world, regardless of whether it’s done in Lua or in an object-based system, and an object-based solution has the additional disadvantage that statements will not benefit from branching conditions with anywhere near as much readability or flexibility.

2. I’m simply having trouble understanding why every change to methods is going to break Lua support with any frequency at all – i.e., why there is even a scrutiny process at all rather than automated unit testing or just waiting for an actual bug report. The removal or changing of the arguments of bound functions or variables will break support, but additions to code generally won’t. There’d simply be an absence of new bindings reflecting the new features, which in itself wouldn’t be anything worse than unfortunate. If it actually breaks compilation, that’s another matter, of course.

The cost-benefit ratio approaching zero I mentioned implies the denominator is increasing, I might add. The more popular the project gets and the more people contribute their own modifications to the world at large without having to fork the project or submit it for internal review, the higher the benefit that is realised for the same linear cost, as compared to hard code which is lower fixed cost, but also fixed benefit.

3. Data-driven bindings are “too much” on the basis of essentially writing a scripting engine where each statement is an object rather than a black-boxed call and return in an embedded language explicitly designed for that purpose. A system similar to StarCraft’s map editor triggers can work, but scripting would get the same thing done far more effectively, and more quickly, without as many esoteric workarounds like the “minions” in League of Legends, the “cloak spells” in Skyrim, and so on.

Scripting also offers greater power and flexibility for the person doing the scripting (especially when it comes to access to program flow control statements such as for/foreach/while loops and branching conditionals, which in my experience scripting is truly awful without). A singular new “generic” function bound to Lua takes only a bit of effort to write a setter/getter, and runs lean and mean, though it incurs maintenance overhead on the back end – a new data-driven event trigger based on an object incurs a larger memory and CPU footprint on the front end and depending on how non-generic it is, also requires a larger amount of new hand-written supporting code to implement.

Since I am indeed probably wearing Bethsoft games thin, another modern moddable indie game with a robust scripting language is Starbound. (I lost around four months’ worth of work on one of my Starbound mods when my hard drive failed last summer, which was a massive bummer… still haven’t gotten back into it.) Anyway, vanilla Starbound ranges from merely okay to good, but modded Starbound is fantastic. The game is also entirely external logic – all of the gameplay logic proper is external, which is an interesting blend between closed-source and open-source, and it’s quite possible to change the entire game to one’s content. Everyone still only makes tweaks to it: it is still Starbound-the-game, yet the modifications that are there fundamentally change the experience, almost universally for the better, because everyone can pick and choose the features they love the most. (There is indeed a rule-of-one incompatibility there, too, if someone overwrites the same core script. But generally mods strive to avoid that whenever possible by just adding their own scripts.)

All in all, I’m getting as tired of arguing this as you are. Ah well. I tried. =)

[Zhilkin]

You should not have been arguing at all. There is no sense in that. All you need to do is to create some mods which will prove that Lua is useful or make some PRs to flesh out Lua bindings. Kevin complained on several occasions for last year or two that nobody is using Lua in large mods (actually even in smaller ones) - no new mods appeared since that time (save for my examples).

If some new large mod would appear - that way Lua could be saved 2016 or 2017. There were plenty of active mergers at that time. I don’t know if it is even possible now with only me, Rivet and kevin (and very rarely others) working with merges, but you have indefinite time until 0.D.

I am personally all for Lua to stay and expanded, but I am very disappointed that it is not being used by others and I have limited time to contribute to dda-lua myself.

[Arche_Zwei]

manufacturing equipment to mass produce parts like steel plates and re-establish industry (giving a function to every Macguffin machine that appears in factories);

Now THAT I would be interested in doing.

I also wanted to add more climatic zones to the map.
DF draws the mountains first, then similates wind, temperature and rain. Then places biomes. Then places civilizations (or in our case human cities, which then could crumble to their simulated end, collected in legends).

But how does LUA make one achieve this? I guess its better for this thsn scripting sand banks and island cities.

I however know only how to compile from source. And have been looking for a guide to get to change anything more complex than the starting screen.

But when I lived on a small tropical island in the middle of the ocean I dreamt of C:DDA taking place there as well.

Would have loved to set up a tent in the main road junction, cleared of people. And set out to scavenge drinking water from whereever and other stuff from the Shops nearby.

[Robik]

Is it possilbe to write a mod in LUA, which would iterate through all items and set “spoils_in” to 0 (to never spoil) for all items where “spoils_in” > some number ?

Edit: by item, I mean item type, not all items that are existing in the world

[Zhilkin]

All items like where? In player inventory?

[Robik]

All items like where? In player inventory?

item type, not all items that are existing in the world, sorry for messy wording

[Zhilkin]

Won’t be possible right now.

[lispcoc]

Can I make PRs to extend lua bindings?
There is work branch to exntend lua bindings has proceeded by @BevapDin(GitHub). I’m afraid of affecting his work.

[Zhilkin]

Sure, you can create PRs.

[lispcoc]

Thx! I’m planning to expose classes and functions to lua.

[overthrow]

Can I get a good example of how to view time durations on today’s experimental?

When I attempt to convert a time_duration via tostring, I get a result like "time_duration_metatable: 0x[pointer or reference address]. I can’t seem to view them, and I can’t seem to compare them with ints, I just get errors about comparing ints to time_duration_metatables, or more confusingly, time_duration_metatables to time_duration_metatables. Any help?

[Zhilkin]

Use game.get_time_duration or wrapper functions from ./lua/autoexec.lua (TURNS, MINUTES, HOURS and DAYS) - see https://github.com/CleverRaven/Cataclysm-DDA/pull/24140.

[lispcoc]

I suppose there may be no LUA API such converting time_duration to integer. It is necessary that add function definition like
{ name = "to_turns", rval = "int", cpp_name = "to_turns<int>", args = { "time_duration" } },

[lispcoc]

Hmm… I’m trying to expose c++ classes and functions to LUA, and thinking about what functions to be exposed.

1. Expose all functions as possible. (except less game rerated classes)
2. Expose functions I’m planning to use only now.
3. Discuss and decide what functions to be exposed.

1 requires very big changes. 3 may be waste of time. I suppose 2 is the better. What do you think?

[Zhilkin]

There is no sense to expose anything you won’t use.

[TheZoneWizard]

You must be married to an angry woman… wink

[Azure_Soul_Azur]

Seems jap mods use Lua more then others… reminds me of playing roblox and making my mini games… temted to relearn Lua and start making weird and crazy shit here in cata…

If life allows me to…

[lispcoc]

feel free to use Lua…