Testing and Debugging `awesome/rc.lua`

Question

How to run lua commands from awesome/rc.lua in an interactive iterpreter?

I'm trying to create some functions in ~/.config/awesome/rc.lua for new key bindings. Sometimes I get an error and I want to test these functions by printing the tables and variables in a command line. I downloaded lua5.2 and I started playing with the interactive interpreter. I wrote a small script that I run at the beginning of the interactive mode.

I'm having a problem when I require("gears") and require("awful") and pretty much every other library found in /usr/share/awesome/lib/. Here are some examples:

1. When attempting to require("gears"), I get the error: /usr/share/awesome/lib/gears/wallpaper.lua:17: attempt to index global 'screen' (a nil value)
2. When removing the line with require("gears"), the line require("awful"), gives me: /usr/share/awesome/lib/awful/tag.lua:603: attempt to index field 'client' (a nil value)

It seems that for every module in the awesome library, There is some component not known for the lua interpreter. How do I tell the lua interpreter to be aware of these components?

I'm not very experienced with lua coding. Am I digging in the wrong place? Is there a different and perhaps better way to test functions from awesome/rc.lua?

Answer 1

Mod4 + x runs a Lua interpreter.

rc.lua and the various Lua lib files are loaded into an environment provided by the host program (written in C). This is why you have access to the provided API elements like screen and client. See the (partially) responsible file here.

If you're just looking to debug some basic Lua functions in the config file, you could consider simply writing to a file or pipe, rather than stdout, and monitoring that instead.

Mod4 + Control + r restarts Awesome, and reloads the config file.

Answer 2

The problems you're facing are caused by the fact that you're running your script outside of the environment provided by awesome. One thing you can do to overcome this is add debug statements:

naughty = require('naughty')  -- if not yet loaded
naughty.notify({text='some message'})
naughty.notify({text=some_string})
naughty.notify({text=tostring(some_number)})
naughty.notify({text=tostring(#some_array)})  -- for array w/o holes

and restart awesome (Mod4 + Control + r).

Alternatively you can ask awesome to run a script you provide:

$ awesome-client '
  naughty = require("naughty")
  naughty.notify({
    text="some message"})
'

The thing with this method is, as long as you debug your code, it's probably fine. But if you want to figure out what's going on in some library, like lain... require doesn't require files twice. If you want to require a file that has changed since the time awesome was (re)started, you've got to dofile (with an absolute path and extension, package.path is used only by require):

bat = dofile "/usr/share/lua/5.3/lain/widget/bat.lua"
bat({})

You can also define some function in rc.lua:

function f1()
    naughty.notify{text='some text'}
end

and then call it via Mod4 + x.

You can check syntax of rc.lua by invoking awesome -k.

And in some simple cases where you don't need the awesome environment, you can just run standalone scripts (lua5.3 /tmp/a.lua, or /tmp/a.lua if it has the shabang).