Here is the aforementioned patch to extend Lua 5.1.2's
exception-handling capabilities. I know Colin in particular expressed
interest, though others would probably find it useful as well. It should
simplify any C++ code bound to Lua, as well as making lua_call a safer
proposition (it throws an exception rather than panicking and exiting).
There's more information in the provided README, as well as in my
previous message.