Re: linking tables to C++ objects?

[Graham Wakefield <lists@...>]

Thanks, but I think perhaps I wasn't clear enough about my needs; see  
below:

On Feb 26, 2007, at 1:56 PM, Sam Roberts wrote:

> > REGISTRY[weakvaluedtable][table] = ptr
>
> ^-- probably unnecessary, see below
>
> > // from C++ ptr to table:
> >
> > getfenv(REGISTRY[weakvaluedtable][ptr])
> >
> > // from table to C++ ptr:
> >
> > REGISTRY[weakvaluedtable][table]
>
> Why would you would you want to map the table to the ptr?
>
> lua code will have only a udata, and will pass a udata to C code,  
> your C
> code will call lua_touserdata() to get the ptr. No table required.

Because I want to call back into the lua State from C++ at a later  
point in time (after the main Lua chunk has run).  That's why I need to
	A) prevent the table being collected until I'm ready
	B) get to the userdata/table from a raw pointer

> >
>
> Optional: if you need to go from udata -> table, maybe to store some
> number of lua values with your udata, thats what lua_getfenv() is for.

Yes, but how do I get to the udata from a raw C++ pointer, after the  
main Lua chunk has run (i.e. in response to a C++ event)?