How do I return multiple modules in Lua?

Question

How can I return multiple tables/objects in Lua? I have this in file1.lua:

local A = {}
function A.new()
    o = {}
    return o
end
local B = {}
function B.new()
    o = {}
    return o
end

return A        --And I want to return B

And I want to use them both in file2.lua:

local A = require "file1"
a = A.new()
b = ?

Your code defines A and B as globals, and so they are accessible in file2.lua. — lhf, Apr 03 '19 at 20:39
My original answer was, indeed, incorrect. The next best solution is probably: https://stackoverflow.com/questions/9470498/can-luas-require-function-return-multiple-results — brianolive, Apr 04 '19 at 11:09

val - disappointed in SE · Accepted Answer · 2019-04-04T15:25:48.887

You probably can return few results like this:

return A, B
…
local A,B = require "file1"

But this is a bad idea because of caching and will likely fail.

Better put them both into table:

return {A = A, B = B}
…
local file1 = require "file1"
local A,B = file1.A, file1.B

UPD: This will work only in lua 5.2+, but probably is shortest and clearest one:

return {A, B}
…
local A, B = table.unpack(require "file1")

You can use any on last two.

How do I return multiple modules in Lua?

1 Answers1