Re: void* in Lua_State for Application?

[Philipp Janda <siffiejoe@...>]

Am 01.09.2013 18:32 schröbte Jo-Philipp Wich:
> What about using container_of() [1] ?
>
> struct LuaPrivateState {
> 	lua_State *pVM;
> 	void *extra_data;
> 	struct foobar baz;
> };

This is basically what Mikhail proposed, but it will only work if the 
lua_State is included in LuaPrivateState by value and not by pointer 
(and lua_State is an incomplete type, private to `lstate.c`, so you 
can't include it by value).
There already is a LuaPrivateState equivalent in lstate.c:

    typedef struct LX {
    #if defined(LUAI_EXTRASPACE)
      char buff[LUAI_EXTRASPACE];
    #endif
      lua_State l;
    } LX;

exactly for this purpose, but it is not accessible outside of `lstate.c`.


> And in a function that gets a pointer to the lua_State, do:
>
> int whatever(lua_State *L, ...)
> {
> 	struct LuaPrivateState *state =
> 		container_of(L, struct LuaPrivateState, pVM);
>
> 	...
> }
>
>
> 1: http://www.kroah.com/log/linux/container_of.html
>
> ~ Jow

Philipp