multi files with esp8266 - lua

Question

I am new to the ESP8266 and lua, is it possible to work with multiple files on the ESP8266 ?
I have 2 files the first one called foo.lua
and it contains this code :
function double(n)
return n * 2
end
and the other file new.lua just call the first file as following:
require 'foo'
print(foo.double(5))
So can i use this technique with the esp8266 ?
I tried that but when I press save to esp button i get
and
and another popup messages
and these get printed on the console :
> file.remove("foo.lua");
> file.open("foo.lua","w+");
> w = file.writeline
> w([[function double(n)]]);
stdin:1: open a file first
> w([[ return n * 2]]);
stdin:1: open a file firstw([[end]]);
stdin:1: open a file firstw([[]]);
stdin:1: open a file firstw([[print (double(2))]]);
stdin:1: open a file firstfile.close();dofile("foo.lua");
cannot open foo.lua
even when i try to run the file using send to ESP button it works but it will not be saved.

Answer 1

There is a way you can achieve that. But you can't just call like foo.double(5).
I recommend you to try to put your function inside a class. Then you just have to compile it, with the command:
node.compile("foo.lua")
If you use the explorer, write it in the bottom right of the program, where you have a send button.
To create a class you should use a template, I recommend you to use this one:
function Class(members)
local mt = {
__metatable = members;
__index = members;
}
local function new(_, init)
return setmetatable(init or {}, mt)
end
local function copy(obj, ...)
local newobj = obj:new(unpack(arg))
for n,v in pairs(obj) do newobj[n] = v end
return newobj
end
members.new = members.new or new
members.copy = members.copy or copy
return mt
end
And in your foo.lua just include this:
require'Class'
If you want to use class variables write them here and then
local foo_mt = Class(foo)
After that you can add all the defs you want.
Don't forget to finish with return foo;