Re: Questions about luabind::object

luabind::object keeps objects in the Lua registry:
http://www.lua.org/manual/5.1/manual.html#3.5
So you can safely pop your object from the stack and it won't be
garbage collected. The lifetime of the object is indeed controlled by
TheChunk - luabind::object will remove the value it holds in its
destructor (before you ask, copying luabind::objects is ok and storing
different luabind::object instances holding the same Lua object works
as expected - the Lua object is removed from the registry and
therefore left vulnerable for garbage collecting only when the last
instance of luabind::object is destroyed)

As for your first question, I believe construction of luabind::object
doesn't have any reasons to modify the stack. And it's easy to verify
that in practice.

On Thu, Dec 3, 2009 at 9:14 AM, Jason McKesson <[email protected]> wrote:
> I have a question about the interaction with the stack for
> luabind::object instances and lifetimes.
>
> OK, so I have a lua chunk. I have loaded it with lua_load. Therefore, it
> is on the stack at index -1. So if I do:
>
> luabind::object TheChunk(luabind::from_stack(pState, -1))
>
> The variable "TheChunk" will hold this function.
>
> So question 1: Is the function still on the stack? It looks like it is
> from the documentation, as it says that "This will create the object o
> and copy the value from the top of the lua stack."
>
> Question 2: If it is still on the stack, what happens to the object if I
> pop it off of the stack? Is the object in danger of being garbage
> collected after popping it, or is the object lifetime now controlled by
> the lifetime of "TheChunk"?
>
> Question 3: If the object holds a copy, exactly where is this copy? If
> the copy is considered a valid Lua reference (thus making it ineligible
> for garbage collection), how exactly does that work? How does Luabind
> accomplish this?
>
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