Re: storing a lua closure in a C object, then calling it from C?

["lists@..." <lists@...>]

Hi,

I'm relatively new to Lua, and I've hit a conceptual block about  
which I'd really appreciate some more experienced input.

I want to create objects in Lua that are tied to some C data  
structure (created from my own allocated memory pool), but also to  
user-defined Lua functions.  At a later point, I will need to iterate  
through my allocated C objects and call the associated Lua functions  
in turn (along with associated upvalues, and passing in the C data  
structure as an argument).  I'm looking for the most efficient  
solution to this problem, scalable to hundreds (or more) such  
objects.  All calls will be made in a determinate order, so there  
should be no thread-unsafe issues.  The objects shouldn't be  
allocated or gc'd by Lua, since I'm using a memory pool, but some  
kind of equivalent gc notification to trigger recycling might be  
useful on either the Lua or C side.

I understand (I think) the difference between light and full  
userdata, but I haven't figured out yet how I could associate a  
reference to a Lua function into my self-allocated C data structure.   
I've seen examples of storing function references as strings, but  
that seems both unsafe and inefficient for my purposes (and prevents  
storing anonymous functions/closures).  I can see how to push and  
read C functions from the Lua stack, but not Lua functions/closures.   
I also read something about the registry (but haven't totally  
understood it yet) - would that help?  Could I use a light userdata  
as a key in the registry?

Or is there a simpler method I'm overlooking?

Thanks in advance!

Graham