The global table

The one thing you really need to understand about Lua is that just about everything in it is a table. Global variables in Lua (variables not declared local) live in an invisible, global table. This table is exposed as _G. This global table is just like any other table in Lua; you can perform the exact same operations on it. This section will explore two methods of working with the functionality of the global table.

Explicit variables

The loose, typed nature of variables in Lua can be great for prototyping games quickly, but it can also lead to a lot of bugs! For example, consider the following code:

five21 = 521 -- Variable name ends with a 1

for i=1,1000 do
  if i == five21 then
    five2l = "Five Twenty One" -- ERROR! Variable name ends with an l
    break
  end
end

print("value: " .. five21)

Can you spot the problem? During the first assignment, the five21 variable ends with a 1, but in the second assignment it ends with a lower case l. Characters such as 0 and O, 1 and...