-- strict.lua -- checks uses of undeclared global variables -- All global variables must be 'declared' through a regular assignment -- (even assigning nil will do) in a main chunk before being used -- anywhere or assigned to inside a function. -- distributed under the Lua license: http://www.lua.org/license.html local getinfo, error, rawset, rawget = debug.getinfo, error, rawset, rawget local mt = getmetatable(_G) if mt == nil then mt = {} setmetatable(_G, mt) end mt.__declared = {} local function what () local d = getinfo(3, "S") return d and d.what or "C" end mt.__newindex = function (t, n, v) if not mt.__declared[n] then local w = what() if w ~= "main" and w ~= "C" then error("assign to undeclared variable '"..n.."'", 2) end mt.__declared[n] = true end rawset(t, n, v) end mt.__index = function (t, n) if not mt.__declared[n] and what() ~= "C" then error("variable '"..n.."' is not declared", 2) end return rawget(t, n) end