[Q] Catch lua error

[trsh]

Can I catch and Faulty lua code, and get some stack trace without panicking the main Rust code?

[trsh]

Additionally how do I set a glob val that is == nil / empty?

[trsh]

Never mind

[naturallymitchell]

@trsh you're gonna post a good question, figure it out, then leave us hanging?

what'd you find??

[trsh]

@mitchtbaum for the 1st question:

      let eval_res = lua.eval::<String>(code, None);
      match eval_res {
        Ok(val) => {
          
        }
        Err(e) => {
          
        }
      }

e will contain Lua errors.

For the nil question, my answer is just not to set that Global. And it will be nil, as all undefined variables in Lua.

[naturallymitchell]

@trsh these say to use xpcall. is that another approach?

• Get true stack trace of an error in lua pcall
• stacktrace-patch.lua

what about try-catch error handling exception pattern? are these ever used together?

I posted an issue in the framework I'm working on. if you're also interested in actix-web and lua, then I'd love your input.

[trsh]

@mitchtbaum sorry, I can tell nothing more. My approach is working for my project, so i dont investigate further. And I use actix-web.

[trsh]

@mitchtbaum one thing that I wan't, and could not figure out, is how to get print (printed stuff in lua), to Rust back. If you know that, let me know. For now I throw exceptions to debug stuff.

[naturallymitchell]

I'm not sure I understand. what is the goal? to pipe stdout back to Rust? I thought you already showed you can get the error object. Does throwing an exception give different debug output?

[naturallymitchell]

I think if it happens anywhere in my code base, it'd be here

https://github.com/foundpatterns/torchbear/blob/aadee3f603c9a1d1dd2ded5d3f579300a704561a/src/lua_bindings/log.rs#L6-L15

that receives strings from Lua to use in Rust code, I think evidenced by its use of push and push_str()

we're not using it anymore, since we switched to using log.lua

[trsh]

Throwing an exception returns Error to Rust, that includes the error lines. Ok result return whatever you return with "return xx". So Print invisible.