The require function that comes with Garry's Mod has been modified by Garry for his needs and programming style, and as a result much of its original functionality is missing. This addon monkey patches the global environment to reimplement some of this missing functionality, and allow for traditional style modules in Garry's Mod.

• Reimplemented package.preload.
• Reimplemented package.loaders. (You can even add your own searcher functions. See source code for more information.)
• Reimplemented package.path
• Detoured require to reference package library keyvalues and allow for return values
• Added package.environment, which is used as the global table for custom modules. By default, it mirrors a basic Lua 5.1 environment.
• require 'gmod' can be used to get a reference to the default global environment, i.e. require('gmod').Msg('hello, world!')
• Basic support for Lua 5.1 modules (must be pure Lua and take note of package.environment limitations)

package.path:

'?.lua'
'?/init.lua'
'lib/share/lua/5.1/?.lua'
'lib/share/lua/5.1/?/init.lua'

package.loaders

• stock Lua module loader (loads modules from includes/modules)
• custom Lua module loader (loads modules according to package.path)
• binary Lua module loader (loads modules from includes/modules)

autorun/test.lua:

--  We still need to send the file to the client if we plan on requiring it
--  there
AddCSLuaFile 'wauterboi/data/constants.lua'

--  There is no need to pollute the global environment - `require` supports
--  return values
local x = require 'wauterboi.data.lorem_ipsum'
print(x.standard)

--  This does not re-execute the module - it's simply fetching the cached
--  return values from `package.loaded`.
y = require 'wauterboi.data.lorem_ipsum'
print(y.translation)

wauterboi/data/constants.lua:

print 'Hello'
return {
  standard = 'Lorem ipsum dolor sit amet',
  translation = 'The customer is very happy'
}

Output:

Hello
Lorem ipsum dolor sit amet
The customer is very happy

There is basic support for Lua 5.1 modules. There are some important caveats to keep in mind, however:

• The file and io libraries are completely missing in package.environment. While the missing libraries could probably be reimplemented, doing so is outside the scope of this module.
• The debug library is missing a lot of functions.
• The modules must be pure Lua.

By default, package.path expects these types of modules to exist inside the lib folder. This is so you can run luarocks install <module> --tree lib. If you're not a fan, you can modify package.path to fit your needs - preferably by appending or prepending paths.

This builds on Linux with moonc and a Makefile. Run make.