1-- 2-- strict.lua 3-- checks uses of undeclared global variables 4-- All global variables must be 'declared' through a regular assignment 5-- (even assigning nil will do) in a main chunk before being used 6-- anywhere or assigned to inside a function. 7-- 8 9local getinfo, error, rawset, rawget = debug.getinfo, error, rawset, rawget 10 11local mt = getmetatable(_G) 12if mt == nil then 13 mt = {} 14 setmetatable(_G, mt) 15end 16 17mt.__declared = {} 18 19local function what () 20 local d = getinfo(3, "S") 21 return d and d.what or "C" 22end 23 24mt.__newindex = function (t, n, v) 25 if not mt.__declared[n] then 26 local w = what() 27 if w ~= "main" and w ~= "C" then 28 error("assign to undeclared variable '"..n.."'", 2) 29 end 30 mt.__declared[n] = true 31 end 32 rawset(t, n, v) 33end 34 35mt.__index = function (t, n) 36 if not mt.__declared[n] and what() ~= "C" then 37 error("variable '"..n.."' is not declared", 2) 38 end 39 return rawget(t, n) 40end 41 42