Writing a proper Lua 5.1 module with functions

Question

I'm working with a program that has standard Lua 5.1 embedded and am trying to write a module I can call functions from but have had no avail.

The current environment is quite picky, and if I make mistakes the scripts will break but will not get any errors, so here we go:

I have something like this (inside moduletests.lua):

local _ = {}

function _.prints()
    HUD.AddUpdateBoxText("Hello World!", 200) --Equivalent to print()
end

I would then attempt to require this and call it with:

mts = require 'moduletests' --seems to cause no issues
mts.prints() --breaks the scripts

Normally if the require function is incorrect, the scripts will break. The scripts work fine with the require, so I assume it is correct, but on any attempt to call the print function it will break.

On the other hand, I have another lua module installed and have been able to successfully require it and call a function and it is what I modeled my module after. This is the module's code.

Here is how I used it:

moses = require 'moses' --Works

local bok = moses.isInteger(6)
HUD.AddUpdateBoxText(tostring(bok), 700); --Works, outputs "true"

And this worked fine, perfectly as intended. Can someone tell me what is different or wrong with my module, or have any suggestions on how I could make a better functional version of this?

Thank you to everyone, I sincerely appreciate the help! Much appreciated!

Veer Singh · Accepted Answer · 2015-10-24 22:10:58Z

2

In Lua modules, you have to return something. The reason your code isn't working is because you are trying to call a method from whatever is returned by the module, but since nothing is being returned, an error can only be expected. Try returning the table:

local ar = {}
function ar.prints()
    HUD.AddUpdateBoxText("Hello World!", 200) --Equivalent to print()
end
return ar

answered Oct 24, 2015 at 22:10

Veer Singh

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1 Comment

Dan McCarthy Over a year ago

Perfect! This answered my question perfectly, was very easy to understand and very concise! Thank you, I really do appreciate the help! Makes perfect sense. :)

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