-- import.lua -- -- Implement the 'use' function to make functions visible in the global -- environment. -- -- Strict mode can be enabled with use'strict'. -- In this mode, uses of undeclared global variables are checked. -- 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. -- -- Copyright (C) 2009-2013 Francesco Abbate -- -- Contributions made by Lesley De Cruz. -- Some parts are adapted from the 'strict' module included in Lua 5.1. -- local _G, rawget, rawset, error = _G, rawget, rawset, error local getinfo = debug.getinfo local function what () local d = getinfo(4, "S") return d and d.what or "C" end local function new_env() local lookup_env = {} local declared = {} local use_strict = false local function check_declared(n) if not declared[n] and what() ~= "C" then error("variable '"..n.."' is not declared", 3) end end local function check_assign(n) if not declared[n] then local w = what() if w ~= "main" and w ~= "C" then error("assign to undeclared variable '"..n.."'", 3) end declared[n] = true end end local function index(t, n) local v = rawget(_G, n) if use_strict and not v then check_declared(n) end return v end local function newindex(t, n, v) if use_strict and not rawget(_G, n) then check_assign(n) end rawset(_G, n, v) end local mt = {__index = index, __newindex = newindex} local function loader(...) local n = select('#', ...) for i = 1, n do local module_name = select(i, ...) if module_name == 'strict' then use_strict = true else local m = rawget(_G, module_name) if m and type(m) == 'table' then for k, v in pairs(m) do if k ~= 'use' then rawset(lookup_env, k, v) end end else error('module ' .. module_name .. ' not found') end end end end lookup_env.use = loader setmetatable(lookup_env, mt) return lookup_env end function restore_env() setfenv(0, _G) end function use(...) local level = debug.getinfo(3, "") and 2 or 0 local env = new_env() env.use(...) setfenv(level, env) end