Lua, ToLua and object instances

[Mike Stoddart <stodge@...>]

I'm using Lua 4 and ToLua to embed Lua in my C++ application.

I'm a little confused about something relating to objects and instances 
of objects. I'd appreciate it if you could just point out whether my 
assumptions are correct.

1)
I use ToLua to create the bindings for my C++ class A.
I create an instance of this class in my C++ code.
That instance is now visible to C++ but not to Lua.
I then expose the instance to Lua; the instance is visible to both C++ 
and Lua.
Is the variable in Lua a reference to the C++ instance, or is it a 
completely separate entity (instance)?
I delete the instance in C++. The variable still exists in Lua, but 
what value does it have? I presume that the deletion doesn't 
automatically get filtered to Lua. How would I deal with this?

2)
I create an instance of an object in Lua. The instance is only visible 
to Lua and not C++.
I delete the instance in Lua, and the C++ code is none the wiser that a 
new instance ever existed.

Thanks, appreciate it.