Need for help...

[Asko Kauppi <Asko.Kauppi@...>]

Does anyone know what 'lua_newuserdata()' really is and why / where it
should be used?

I'm doing an (experimental) gluax compatibility cover over old-style C API.

The following extract is from 'luasocket.c':

    /* declare new Lua tags for used userdata values */
    p_tags tags = (p_tags) lua_newuserdata(L, sizeof(t_tags));
    tags->client = lua_newtag(L);
    tags->server = lua_newtag(L);
    tags->table = lua_newtag(L);
    tags->udp = lua_newtag(L);

'p_tags' is simply (same source file):

	typedef struct t_tags {
	    int client, server, table, udp;
	} t_tags;
	typedef t_tags *p_tags;

Question is, what is really the importance / need for 'lua_newuserdata()'?
It's not documented in 4.0 PDF and in my understanding, is just a fancy
'alloc'. I must be missing something...?

Declaration in 'luaapi.c':

	LUA_API void *lua_newuserdata (lua_State *L, size_t size) {
	  TString *ts = luaS_newudata(L, size, NULL);
	  tsvalue(L->top) = ts;
	  ttype(L->top) = LUA_TUSERDATA;
	  api_incr_top(L);
	  return ts->u.d.value;
	}

-ak

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