-- trace assigments to global variables
do
-- a tostring that quotes strings. note the use of the original tostring.
local _tostring=tostring
local tostring=function(a)
if type(a)=="string" then
return string.format("%q",a)
else
return _tostring(a)
end
end
local log=function (name,old,new)
local t=debug.getinfo(3,"Sl")
local line=t.currentline
io.write(t.short_src)
if line>=0 then io.write(":",line) end
io.write(": ",name," is now ",tostring(new)," (was ",tostring(old),")","\n")
end
local g={}
local set=function (t,name,value)
log(name,g[name],value)
g[name]=value
end
setmetatable(getfenv(),{__index=g,__newindex=set})
end
-- an example
a=1
b=2
a=10
b=20
b=nil
b=200
print(a,b,c)