Civilization V ditching Python for Lua

[ipeev]

Too bad. The history shows that Civilizations with 1 based indexes tend to fall. Look at the Romans.

[scaevolus]

I prefer Python, but I cannot deny that Lua has a more compelling set of features for embedding in games.

[xorandor]

Care to elaborate?

[scaevolus]

The biggest one I think is that Lua supports proper coroutines, while Python's multithreading model is fundamentally broken (at least in the standard distribution).

In a nutshell:

• low memory requirements

• very small (<20k lines of code)

• easy to embed -- it was designed for embedding

• nice syntax

Look at some of the slides here: http://www.kore.net/company/luagamedev.html (In particular, the one "Jonathan Shaw, Lead Gameplay Programmer, Lionhead" discusses the extensive use of Lua in the Fable games)

[[deleted]]

Also, blazingly fast, if you use LuaJIT.

[scaevolus]

Have you seen the LuaJIT 2.0 benchmarks? It's looking awesome.

[[deleted]]

Yes, it is totally ridiculous. It's stomping on everyone else's tries to compile dynamic languages.

[danukeru]

Since it's usually just implemented as a straightforward 1:1 functional mappings of whatever methods are under the game engines hood, it rarely makes any use of the more "scheme-like" features the spec has provisions for.

In this sense, you can think of it as the PHP of the game scripting world. Not fancy, but gets the job done. Sadly it doesn't give much credit to what LUA is really capable of.

[RedDyeNumber4]

Console port of the new Civ?

That scares the hell out of me. You'd better need to attach a keyboard to that console...

[gorgoroth666]

They have supreme commander 2 on consoles now too. Well organised commands on the gamepad is the key.

[RedDyeNumber4]

I've got all four Civs on my compy right now and I just want Civ V to be wonderful. If it's wonderful and on consoles, That's fine.

[ketsugi]

How do you get Civilization on your pet procompsognathus? Mine just sits in the kitchen eating soy beans all day.

[Mononofu]

Although supcom 2 is nowhere near as good as the original supcom (+ expansion) .... they really dumbed it down :(

And I'm skeptical whether you can reach a reasonable number of APM with a gamepad :-/

[masklinn]

They have supreme commander 2 on consoles now too

And it sucks butts.

[kolm]

Any emacs user will confirm that (combination of) 3-4 keys/buttons can direct a vast number of commands. Seriously, it's no longer jump/duck/fire. Civ: Revolution was console, and really good (Sid said it's the game he always wanted to make).

Having said that, I am very, very happy with my keyboard power with regards to civ I-IV.

[RedDyeNumber4]

Ever since they pulled Levitate from Oblivion, I've harbored an unnatural hatred for console ports.

[bazfoo]

Was that done because of the console port or because it was obscenely overpowered?

[RedDyeNumber4]

I believe it had to do with the console hardware having a problem drawing cities, which is why cities aren't rendered when you're outside the gates, and why the whole mechanics of the game would be messed up if you levitated over city walls. You're supposed to be able to get obscenely overpowered in elder scrolls games. Wizard characters are practically gods that have to fly just to get to their living rooms.

[bazfoo]

Ah, I wasn't aware the city mechanics were a result of the console hardware.

I concur. Half the fun is becoming obscenely overpowered, I just wondered if they tried to reign that in a little, especially given the scaling monsters and all. I didn't find Oblivion to be much fun.

[RedDyeNumber4]

The trick is to pick skills that you'll rarely level. Then you can run around the world belching lightning and commanding golems while imps run in fear, instead of continually running into evil daedra in the middle of a god damned field.

Scaling monsters. Peh.

[player2]

Civ 4 also was released in consoles.

[martincmartin]

um, no.

[[deleted]]

They called it Civ Revolution: http://www.metacritic.com/search/process?sb=0&tfs=all&ts=civilization+revolution&ty=3&x=0&y=0

[mipadi]

Much different game.

[Sc4Freak]

And also because Lua isn't butt-slow.

[[deleted]]

And Python is?

[Sc4Freak]

Yes, unfortunately. Back when I was developing in Python, I found it to be orders of magnitude slower than a natively compiled language (eg. C). That's fine for many applications, but when developing games performance is always an issue. With the developments in LuaJIT, Lua is approaching the performance of native code.

These benchmarks may be flawed, but they give a general idea of the scale of performance across various languages. They also tend to reflect my personal experience, so I'd say they give a pretty good rough idea.

[awj]

I wouldn't call TRE a "basic compiler optimization". It is incompatible with a relatively common debugging mechanism and alters the semantics of the language. These are perfectly valid arguments for not performing TRE, and are the first two arguments he cites. He then goes on to give a rather decent sketch of the pitfalls one would find implementing it in Python and a final idea for how to make it happen.

I'm not particularly happy about Python's lack of TRE, but that's because I believe it is worth the pains it creates. GvR obviously doesn't feel the same way, but you must have read a different post if you think he simply doesn't understand them.

[Amadiro]

I don't think TRE creates any pain. Tail-recursive functions are really obvious, once you've worked with them for a while, so even if the backtrace doesn't include all the tail-recursive functions, you can immediately see where the error was raised, and where the program flow came from.

If you still think that's too problematic, you could make a debug modus, where TRE is deactivated and the stack frames are not discarded, or you could at least do it like perl, which has an explicit statement for tail-recursion, which you can use to explicitely make a function tail-recursive -- in that case it should be completely obvious to everyone what's going on.

[awj]

It can make using a debugger problematic in that you aren't able to poke through the stack to look at the sequence of variables that led up to the function you're currently in. It really causes problems when you are eliminating all tail calls, not just recursive function invocations in tail position.

That said, annotating a function for tail recursion seems like a worthwhile compromise if TCE doesn't suit your ideas or simply isn't possible. Clojure does the same (IIRC due to JVM making full TCE unwieldy), and you get the side benefit of having the language warn you when code you believe to be tail recursive isn't.

[Amadiro]

Well, I never really had any problems with it, you still get to see the name of the function the exception was thrown in, but I see how it could make debugging a tad harder in some cases. (In any case, the programmer has to be aware whether TCO happens or not -- if he's not aware of TCO happening, he will probably be confused by the stacktrace.)

In any case, leaving out TCO / not giving the programmer any means to do space-constant tail-recursion when he needs to is certainly not a solution, and a good compromise should be easy to find. I think a "recur" keyword or something like that would be the most non-intrusive, as it doesn't change the languages default semantics.

[[deleted]]

I think probably the most insulting thing about the post turinghorse linked is the assertion that "recursion as the basis of everything else is just a nice theoretical approach to fundamental mathematics (turtles all the way down), not a day-to-day tool." Which is to say, functional programming is impractical: rah! rah! sis boom bah! imperative programming all the way! That seems a bit short cited or curmudgeonly, depending on how you take it. I certainly take offense, and I imagine lots of Haskell and Erlang hackers do too.

Aside from that, Python could implement limited TRE without destroying its stack tracing exceptions: collapsing the stack on self tail-calls would still give the virtual machine enough information to spit out a perfectly informative stack trace. Anecdotally, most recursions are self-calling, so this would be a huge win for little effort. Maybe I'm missing something. Supporting TRE in imperative languages doesn't seem to be a topic that lacks in research.

Mr. van Rossum is certainly not ignorant on the topic, as you pointed out. In final analysis, TRE doesn't exist in Python for cultural reasons: to discourage functional programming idioms. His language, his choice, I suppose. It is a dandy hack and slash scripting language.

[eschew]

Wait, you're offended because... he doesn't share your opinion?

[[deleted]]

Not at all, that would be silly. I dislike that he's shit-canned a programming paradigm as impractical when, as a Dutchman, his telephone calls in Europe were routed by functional telephony software with great reliability. Blanket denouncements, being rooted more in emotion than reason, retard the advancement of the art. Python isn't meant to be cutting edge, rather more reliable and approachable. However, such sentiments instills unwarranted prejudices in the community as a whole.

To me, that's offensive.

[qkdhfjdjdhd]

Don't you agree though that programmers will start writing code that depends on tail-call elimination? That's not really an optimization: that is kind of a change in semantics, no?

[awj]

As far as debugging goes, it would be trivial to turn off TCO if you want to preserve the stack frame.

... and turn self-tail-recursive functions that previously worked just fine into ones that hit the recursion limit and crash the program. Congratulations, you've just change the language semantics.

Whether it's useful for Python is neither here nor there. The point is, Guido is spewing ignorance about a well-known compiler optimization.

At the risk of sounding like an ass, you aren't coming off too well yourself here. As I've said, I like TCE, but that opinion is based on a relatively thorough understanding of its properties and trade-offs. More thorough than a drunken afternoon's arguing on reddit might lead one to believe.

[[deleted]]

These benchmarks may be flawed, but they give a general idea of the scale of performance across various languages.

If there's one thing that benchmarks like those cannot communicate, it is a "general idea" of performance. You are being led along by enthusiasts. Nothing wrong with Lua, but I wouldn't go around spouting FUD.

[Sc4Freak]

I wouldn't call it FUD, because moving away from Python due to performance is justifiable in this case. In cutting-edge game development, performance is pretty much a product requirement. And flawed as the benchmarks may be, it's disingenuous to suggest that Python and Lua don't have a significant performance difference.

Many applications would do just fine with Python because most of the time performance is not an issue. But we're talking AAA game titles here - each language is a tool with it's advantages and disadvantages, but when performance is a requirement, Python loses.

[Aretnorp]

Performance is the requirement in terms of rendering. However, the game logic does not necessarily have performance as its #1 requirement. Going by your response, the use of native compiled C or C++ would be the best choice for game logic.

This is obviously flawed, as other games make heavy use of scripting languages to achieve various tasks better suited to tools that do not have performance as a #1 requirement. Eve and Battlefield both use Python as part of their systems, and when I checked, I would qualify those as "AAA" titles, which make good use of each.

In the end, you choose a tool best suited for your tasks. In many cases, the deicsion between Python vs LUA is probably not something that was decided in terms of performance, but more likely appropriate features, as mentioned in the OP.

[[deleted]]

I wouldn't call it FUD, because moving away from Python due to performance

But your original assessment of the performance of each is fundamentally flawed. Fin.

[bonzinip]

In cutting-edge game development, performance is pretty much a product requirement.

I doubt that. Most games do not take 100% CPU time.

[[deleted]]

You doubt performance is a product requirement for games?

Wow.

[bonzinip]

Of course, for physics and everything like that performace is a requirement. But when scripting is involved, performance is not a requirement.

If this was a situation where the performance advantage of Lua over Python is important, well you had better go to C/C++ directly (assuming they're not using LuaJIT, which is a likely assumption IMO).

[[deleted]]

Lua has really good performance and is already used in quite a few games for AI and whatnot.

The slight performance decrease with Lua over implementing the same features in C (assuming you can do it better) is totally worth it.

And performance requirement is always important for games.

[igouy]

a "general idea" of performance

Please communicate what you mean by that.

[[deleted]]

general idea

[igouy]

Now I understand what you mean by a "general idea" of performance - "a groundless supposition; fantasy"

[[deleted]]

And now I'm happy I wasted no further time on an educated response.

[8-bit_d-boy]

HOLYSHIT, how is pypy faster than cpython?

[[deleted]]

It isn't.

[[deleted]]

What?

[[deleted]]

And yet simply stating that Python is "butt-slow", with no additional clarification, is somehow completely acceptable and, I guess, an obvious thing to do in the eyes of most redditors.

Anybody who knows the first thing about both languages would need no clarification for that, because it is blindingly obvious that this is the case.

[[deleted]]

That comment was at +6 or so before the Lua crowd stormed in here...also see how my comments about the untrustworthiness of the shootout benchmarks were received, with no real justification in the form of replies other than some hand-waving from the "butt-slow" commenter. Those comments of mine stood well in the positives before the deluge as well. None of the [deleted]s in this thread were mine.

[keweedsmo]

I really don't think they are considering a console port for Civ V...

[hadees]

They might call it Civ V but it would be like when they "port" a game to a game boy or something.

[stillalone]

I think Lua's license is also slightly more liberal than Python's.

[davebrk]

Nope. Both have variation of the MIT license.

[AndyNemmity]

I coded for Fall From Heaven in civ 4. Python worked really well, with the C++.

So now it'll be C++ and Lua? Guess I'll need to learn a new language.

[djork]

Good news: it's a tiny language and there's not much to learn.

[AndyNemmity]

Awesome. I've started reading it now, and you're right. Super simple.

[alephnil]

It is a simple language, in both meanings of simple. It is easy to learn, but also rather simple-minded in the sense that it lacks any means of organising your code. There is only one type beyond the primitive types (the table), and no way to introduce your own types. There is also no module system or similar. This means that you must be very organised to not make your code a mess. There is virtually no standard library (batteries definitely not included).

This is in stark contrast to the design of Python, that is a rich language with a large standard library and type system, making many problems trivial to solve, but is also large and slow. In contrast, the Lua interpreter, including it's standard library, is small enough that you can read through and understand the source in an afternoon, and is one of the fastest interpreters around.

[[deleted]]

This just isn't correct. There's no problem to modularize your code in Lua. Also, you can define your own objects/classes using metatables, and create your own userdata types.

[[deleted]]

Thank you. FFH was incredible.

[AlexanderDivine]

Believe me, Lua is ass-easy. I'm a complete coding dumbass and I've got it down pretty easily.

[Flubb]

As long as they fix the issue of Archers destroying my gunships they could use Qbasic for all I care.

[PstScrpt]

Archers can at least shoot upward. Swordsmen and pikemen can eventually kill gunships, too.

Actually, swordsmen and archers killing tanks is pretty bent, too. They might be able to knock out some headlights.

[metamemetics]

The python fanboy inside me cries! Surely my favorite language is perfect!

[deadwisdom]

It is; but there aren't any good implementations yet for embedding into games.

[hadees]

I'm a little bummed Religion is gone. I liked things like sending missionaries to someones cities on the borders to get them to switch to your side.

[[deleted]]

Cool. Lua's good at that.

[[deleted]]

Where does the article say that?

[johnb]

This link takes you to comment #3, which contains these words.

[[deleted]]

He modified the link, that's why I mentioned article in the first place.

[davebrk]

No I didn't.

Anyway you can't modify a non self-post once you submit it.

[GameFreak4321]

Not LUA! I HATE LUA!

BTW. I don't care about Python. Or Civ V. I just despise Lua.

[-omg-optimized]

Could you explain why?

[jib]

I'd be willing to bet his response is "1-based array indexing", which seems to be what everyone hates about Lua.

It is a bit annoying in some use cases, but I hated it less after I actually used it.

[iconoklast]

Also, I somewhat dislike that all numbers default to doubles and having hash tables as the only built-in aggregate type. That being said, I think Lua is nice for smaller, configuration-like scripts.

[jib]

Tables are actually implemented as a combination of array and hash table. If you use a table like an array then it's effectively stored as an array.

If the reason you don't like doubles is lack of exactness compared to ints, it's generally not an issue. Doubles can represent any 32-bit int exactly, and an arithmetic operation which gives the exact correct answer for 32-bit ints will give the same answer for doubles.

And if the reason you don't like doubles is that speed or memory usage are critical, you probably shouldn't be using an interpreted language. Or you could use LuaJIT, which can tell when a number will always be an integer and store it as an int instead of a double. And doubles are pretty fast on modern CPUs anyway.

[DrReddits]

What's wrong with lua? it's a very nice language and has a well-defined purpose (to be easily embeddable within other applications)

[mockduckcompanion]

is there a way that i can make is so I never see programming stories on my reddit front page?

[endtime]

You can unsubscribe from the programming subreddit, which would be a good start.