Get global environment in lua package

Question

At the begining of some lua package files, sometimes there will be the line local base = _G or local base = ....

1. What's the benefits for doing this?
2. What's the differences between these two lines?

Answer 1

For the first question, you can refer: Why make global Lua functions local?

For your second one,

What's the differences between these two lines?

When you do local base = _G, you are assigning base to be a synonym for the global environment table. On the other hand, in the statement local base = ...; the ... refer to vararg feature of lua.

It can be shown in better detail with the following example:

local a = {...}
for k, v in pairs(a) do print(k, v) end

and then, executing it as follows:

─$ lua temp.lua some thing is passed "here within quotes"
1       some
2       thing
3       is
4       passed
5       here within quotes

As you see, ... is just a list of arguments passed to the program. Now, when you have

local base = ...

lua assigns the first argument to the variable base. All other parameters will be ignored in the above statement.