Re[2]: Unique object references

[Cloud Wu <cloudwu@...>]

Hello Luiz,

Saturday, December 9, 2006, 7:24:33 PM, you wrote:

>> Is there any way to get a state-wide unique reference to any
>> particular object in the state?

LHdF> The value itself is a good reference. Or you can try lua_topointer.
LHdF> --lhf

Before a lua object collected, the result of lua_topointer is never
changed. Am I right?

Can you guarantee this will not be changed in future version of lua ?
;) I saw some other language may move the objects during the garbage
collection.

I have another question.
When I use lua_newuserdata(or lua_touserdata) to get a pointer to the
memory , can I save it in my C struct directly? or I should use
lua_tousedata to convert the userdata to a pointer every time I need ?

For example:

struct array {
       int n;
       int *data;
};

int array_create(lua_State *L)
{
    int n = luaL_checkint(L, 1);
    struct array* ret=(struct array*)lua_newuserdata(L,sizeof(*ret));
    lua_createtable(L,1,0);
    ret->data=(int*)lua_newuserdata(L,sizeof(int)*n);
    lua_rawseti(L,-2,1);
    lua_setfenv(L,-2);
    return 1;
}

int array_set(lua_State *L)
{
    struct array* a=(struct array*)lua_touserdata(L, 1);
    int n = luaL_checkint(L, 2);
    int d = luaL_checkint(L, 3);
    a->data[n]=d;
    return 0;
}

-- 
Best regards,
 Cloud                            mailto:cloudwu@163.com
            http://blog.codingnow.com

[不患莫己知，求为可知也]