Question

How do you debug lua code embedded in a c++ application?

From what I gather, either I need to buy a special IDE and link in their special lua runtime (ugh). Or I need to build a debug console in to the game engine, using the lua debug API calls.

I am leaning toward writing my own debug console, but it seems like a lot of work. Time that I could better spend polishing the other portions of the game.

Answer 1

There are several tools floating around that can do at least parts of what you want. I have seen references to a VS plugin, there is a SciTE debugger extension in Lua for Windows, and there is the Kepler project’s RemDebug, as well as their LuaEclipse.

RemDebug may be on the track of what you need, as it was built to allow for debugging CGI scripts written in Lua. It does require access to the LuaSocket module to provide a communications channel between the target script and a controller as well as a couple of other modules.

A bigger issue might be the ability to load arbitrary modules from within whatever sandbox the game engine has put around your scripts. If you have some control over the engine, then that won’t be as big an issue.

This isn’t currently possible for developers of Adobe Lightroom plugins, for example, because Lightroom does not expose require inside the plugin’s sandbox.

A surprise to me has been how rarely I have felt a need for a debugger when working with Lua. I’ve built several small applications in it for various projects and have been surprised at how well a combination of complete stack backtraces and the occasional print call works to locate the bugs that require 'strict' didn’t prevent in the first place.