1 files changed, 38 insertions, 0 deletions
diff --git a/test/trace-globals.lua b/test/trace-globals.lua
new file mode 100644
index 0000000..295e670
--- /dev/null
+++ b/test/trace-globals.lua
@@ -0,0 +1,38 @@
+-- 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)