Re: local variables and scope
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- Subject: Re: local variables and scope
- From: Roberto Ierusalimschy <roberto@...>
- Date: 2005年8月25日 10:18:21 -0300
Follows a nice script to detect missing "local" declarations and other
"wrong" uses of global variables.
Simply put it in your path and add require"strict" to your program
(or call "lua -lstrict").
-- Roberto
---------------------------------------------------------------------
--
-- 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.
--
local mt = getmetatable(_G)
if mt == nil then
mt = {}
setmetatable(_G, mt)
end
mt.__declared = {}
mt.__newindex = function (t, n, v)
if not mt.__declared[n] then
local w = debug.getinfo(2, "S").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] then
error("variable '"..n.."' is not declared", 2)
end
return rawget(t, n)
end