Introspection with Lua

[Vineet Jain <vinjvinj@...>]

I'm migrating some programs from python to lua and had some questions 
about introspection in Lua. Specifically I'm looking for the equivalent 
of python's setattr and getattr in Lua.

I need to find out (dynamically) if a certain lua module has some 
functions and variables defined. I also need to set some module 
variables (dynamically).