[kurapica.igas]

If an addon has A.lua(at the top of the toc file), B.lua

A.lua:

local addonName, addon = ...

if not getmetatable(addon) then
	setmetatable(addon, {
		__index = function(self,  key)
                        -- keep vars in the _G to the addon to reduce the access cost
			local v = _G[key]
			if v ~= nil then
				rawset(self, key, v)
				return rawget(self, key)
			end
		end,

		__metatable = true,
	})
end

setfenv(1, addon)

-- Standalone code environment, also all files in one addon share the same environment
function myFunc() end

print(_G.myFunc)  -- nil, you get print from _G, _G won't get myFunc from your addon

B.lua

local addonName, addon = ...

setfenv(1, addon)

myFunc()  -- you can call the function myFunc defined in A.lua