Writing LaTeX macros has always been difficult, and it seems like writing a major package can only be accomplished by a Real Programmer.

Fortunately, LuaTeX is on its way, and writing Lua macros is arguably more human-friendly than programming in TeX. Still, it could get even friendlier if there was a way to couple LuaTeX with a remote debugger.

Therefore I ask: Is there a way to remotely debug LuaLaTeX macros?

This question is essentially a rewording of the post Debugging Lua in LuaLatex with LDT. The post was closed since it didn't really contain a question. An almost-complete solution was proposed in the post, but there were some issues, and I would like to know if these issues can be resolved.

  • Could you explain 'remote' debugging for those of us without a formal programming background? – Joseph Wright Feb 23 '16 at 19:29
  • Basically, I want to write my macro in a file macro.lua, using a text editor with debugging capabilities (such as Emacs or Eclipse). When I compile the .tex document, I want LuaTeX to pass the control over to Emacs/Eclipse, where I can step through the macro line by line, examining (and possibly alter) the contents of macro variables as the program progresses. – akvilas Feb 23 '16 at 19:49
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    @JosephWright debuggers let you single step through compiled languages like C or Fortran so could in principle do the same in lua. – David Carlisle Feb 23 '16 at 20:17
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    Basically can you access something like this from luatex: lua-users.org/wiki/DebuggingLuaCode – David Carlisle Feb 23 '16 at 20:20
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    I usually do printf debugging in combination with viz-nodelist (when appropriate, see for an example output tex.stackexchange.com/a/107398/243). My printf debug functions are here: github.com/speedata/publisher/blob/develop/src/lua/common/…, especially w() and printtable(). – topskip Feb 23 '16 at 20:46

One simple, lightweight alternative is the command-line interface debugger debugger.lua by Scott Lembcke. This is not a remote debugging solution, but it is very easy to set up. On the downside, there is no GUI, so everything is done through the terminal. But it's way better than issuing print commands, which is probably the approach used by most LuaLaTeX package writers to date.

To get started:

  1. Download debugger.lua and place it in your project folder.
  2. Place the command local dbg = require("debugger") at the start of the .lua file you want to debug.
  3. Place the command dbg() at places in your code where you want code execution to break.
  4. Use terminal commands to inspect variables, execute custom code and more. Issue the command h to get a simple summary of available commands.
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  • If someone can give me a simple-to-set-up GUI debugging solution, I'll accept that anwer instead of my own... – akvilas Feb 24 '16 at 7:45

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