this post was submitted on 12 Nov 2023
16 points (83.3% liked)

Programming

17666 readers
354 users here now

Welcome to the main community in programming.dev! Feel free to post anything relating to programming here!

Cross posting is strongly encouraged in the instance. If you feel your post or another person's post makes sense in another community cross post into it.

Hope you enjoy the instance!

Rules

Rules

  • Follow the programming.dev instance rules
  • Keep content related to programming in some way
  • If you're posting long videos try to add in some form of tldr for those who don't want to watch videos

Wormhole

Follow the wormhole through a path of communities [email protected]



founded 2 years ago
MODERATORS
 

The official documentation isn't 100% clear on things (why am I getting LUA_TNIL for functions?), and the best I can find with some simple web search is kinda relevant stackoverflow (🤮) posts, except they're mostly about calling host functions from Lua side, the rest are things that seem I've nailed so far.

EDIT: Solution was that everyone was using luaL_dofile, while I was forward thinking and used lua_load instead, which isn't a macro, and as such doesn't do an initial lua_pcall. Now I do it manually, and now I get different, but less cryptic and actually documented errors. Now I just have to wrestle with D metaprogramming features (very strong and capable, but is a rabbit hole itself).

top 11 comments
sorted by: hot top controversial new old
[–] [email protected] 7 points 1 year ago

Not really sure what you're trying to achieve here. Do you have an application that lets you use Lua extensions? Or do you want to build an application that lets you use Lua extensions?

[–] [email protected] 6 points 1 year ago (1 children)

What do you mean “embedding lua into applications”?

I assume you mean you want an application extensible by user lua script?

You build an API that calls the lua interpreter and passes the script, and reads the output; same as you would for any other scripting language. You define what the inputs should be, create the interface for executing the user defined script through shell commands, and then retrieve the output.

For python you’re going to probably use this:

https://docs.python.org/3/library/subprocess.html#subprocess.check_output

For C# you’re going to use Process

https://stackoverflow.com/questions/4291912/process-start-how-to-get-the-output

The complexities arise in your implementation and there’s no single guide.

[–] samus7070 3 points 1 year ago (1 children)

While lua ships a standalone interpreter, it is very much designed to be embedded directly into an application. This is done by invoking some C apis to load the interpreter into the application’s memory space. OP wants to do that rather than invoking another process and reading the output. When embedding into a host, the host can provide its own objects to be manipulated by the user script allowing for a much better extensibility experience.

[–] [email protected] 1 points 1 year ago

That solution is janky and slow as hell. I'd rather just embed it into my own software, which is mostly done, except it doesn't find functions as functions, but as nil value.

[–] [email protected] 5 points 1 year ago (1 children)

Whats the host language you try to embed lua into?

[–] [email protected] 4 points 1 year ago (1 children)

D.

It has C ABI compatibility, so it should work. But as others wrote, I might have messed up my Lua script.

[–] [email protected] 3 points 1 year ago

Upvote for D, underrated lang.

[–] [email protected] 4 points 1 year ago (1 children)

let me take a guess, gta online modder ?

[–] [email protected] 1 points 1 year ago

No, I'm developing my own engine.

[–] adamnejm 2 points 1 year ago

One Lone Coder has made few videos about adding Lua scripting to a C++ program, maybe it has what you're looking for: Embedding Lua in C++ #1

[–] [email protected] -3 points 1 year ago

Well, reference manual was enough for me. There' nothing difficult. You probably have troubles with your lua code, try executing it in the standalone interpreter.