why do i get "attempt to call global 'require' (a nil value)"?

Question

I have 3 lua files, Init.lua, FreeCamera.lua and Camera.lua ,

init.lua calls require "Core.Camera.FreeCamera"

Free Camera:

module(...)
require "Core.Camera.Camera"

local M = {}
FreeCamera = M

M = Class( Camera )
function M:__constructor(x,y,z)
  self.Active = false
  self.x = x
  self.y = y
  self.z = z
end

and

module(...)

local M = {}
Camera = M

M = Class()

function M:__constructor(x,y,z)
  self.Active = false
  self.x = x
  self.y = y
  self.z = z
end

FreeCamera "inherits" Camera kind of. I am trying to require FreeCamera in my init file and I am getting this:

..\Content\Modules\Core\Camera\FreeCamera.lua:12: attempt to call global 'require' (a nil value). Any idea Why? Am I using require the right way? Clearly it is getting into FreeCamera.lua, which is great, but it gets stuck on the next require.

Norman Ramsey · Accepted Answer · 2009-11-13 05:55:12Z

11

To 'import' identifiers into a module, you might write code something like the following:

local require = require
local Class = Class
local io, table, string
    = io, table, string
local type, pairs, ipairs, assert
    = type, pairs, ipairs, assert

module(...)

local Camera = require 'Core.Camera.Camera'

and so on.

The module(...) command removes (almost) everything from your global-variable namespace—it creates a new global namespace that belongs to the new module. Aside from a couple of special identifiers like _M and _G, the new namespace is empty. But local identifiers stay visible.

The local declarations make the dependencies of your module clear, and they can also communicate your intent. As a bonus, they make access to the named identifiers more efficient. So this is very good Lua style.

answered Nov 13, 2009 at 5:55

Norman Ramsey

204k62 gold badges375 silver badges541 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Joe Over a year ago

perfect! i noticed this in the critique page on the module function, I am glad to know that it is good style!!

lhf · Accepted Answer · 2009-11-12 23:54:11Z

7

The module function creates a new empty environment and so require is not found when called. Try calling require before calling module.

answered Nov 12, 2009 at 23:54

lhf

72.9k11 gold badges117 silver badges162 bronze badges

1 Comment

Joe Over a year ago

That seems to have done the trick, now it says Class() is nil, but if i change that from a global, to require, it should work according to what you are saying.

mxcl · Accepted Answer · 2013-04-15 18:13:16Z

0

You can:

lua module(..., package.seeall)

To import the global environment into your module. This is (presumably) the easiest solution, but may not be to your taste.

answered Apr 15, 2013 at 18:13

mxcl

27k12 gold badges102 silver badges100 bronze badges

1 Comment

RBerteig Over a year ago

This is the expedient solution, but it introduces a bunch of other issues due to inclusion of the global environment inside the module's environment. The current best practice is to avoid the module() function and use local generously. Notice that in Lua 5.2, the function module() is deprecated, for example.

Collectives™ on Stack Overflow

why do i get "attempt to call global 'require' (a nil value)"?

3 Answers 3

1 Comment

1 Comment

1 Comment

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

1 Comment

1 Comment

1 Comment

Your Answer

Sign up or log in

Post as a guest

Related