test/trace-globals.lua

   1 -- trace assigments to global variables
   2
   3 do
   4  -- a tostring that quotes strings. note the use of the original tostring.
   5  local _tostring=tostring
   6  local tostring=function(a)
   7   if type(a)=="string" then
   8    return string.format("%q",a)
   9   else
  10    return _tostring(a)
  11   end
  12  end
  13
  14  local log=function (name,old,new)
  15   local t=debug.getinfo(3,"Sl")
  16   local line=t.currentline
  17   io.write(t.short_src)
  18   if line>=0 then io.write(":",line) end
  19   io.write(": ",name," is now ",tostring(new)," (was ",tostring(old),")","\n")
  20  end
  21
  22  local g={}
  23  local set=function (t,name,value)
  24   log(name,g[name],value)
  25   g[name]=value
  26  end
  27  setmetatable(getfenv(),{__index=g,__newindex=set})
  28 end
  29
  30 -- an example
  31
  32 a=1
  33 b=2
  34 a=10
  35 b=20
  36 b=nil
  37 b=200
  38 print(a,b,c)