Lua strings as "atoms"???

[Chris Marrin <chris@...>]

I want to optimize string compares and pushes when interacting with Lua. 
For instance, in my __index() function I want to do this:

    const char* prop = lua_getstring(L, -1);
    if (prop == mygPrototypeString)
        ...
    else if (prop == mygParentString)
        ...

and so on. The global strings would be created in some init code like this:

    // global variables
    const char* mygPrototypeString = NULL;
    const char* mygParentString = NULL;

    ...

    lua_pushstring(L, "prototype");
    mygPrototypeString = lua_tostring(L, -1);
    lua_pop(L, 1);
    lua_pushstring(L, "parent");
    mygParentString = lua_tostring(L, -1);
    lua_pop(L, 1);

By doing some experimentation it looks like, whenever you push a string 
and then ask for a pointer to it, the same address is always returned 
for that pointer, whether it is still on the stack or not. Is this 
always true? Can the above reliably be used to handle strings as atoms?

Or is there another, better way to do this?

PS - I am imagining also adding some refs (luaL_ref/luaL_unref) to 
global strings like this so I can push them by just pushing the ref. I 
would do this to save the time of hashing the string. Would this save 
enough to be worth it?

--
chris marrin                ,""$,
chris@marrin.com          b`    $                             ,,.
                        mP     b'                            , 1$'
        ,.`           ,b`    ,`                              :$$'
     ,|`             mP    ,`                                       ,mm
   ,b"              b"   ,`            ,mm      m$$    ,m         ,`P$$
  m$`             ,b`  .` ,mm        ,'|$P   ,|"1$`  ,b$P       ,`  :$1
 b$`             ,$: :,`` |$$      ,`   $$` ,|` ,$$,,`"$$     .`    :$|
b$|            _m$`,:`    :$1   ,`     ,$Pm|`    `    :$$,..;"'     |$:
P$b,      _;b$$b$1"       |$$ ,`      ,$$"             ``'          $$
 ```"```'"    `"`         `""`        ""`                          ,P`
"As a general rule,don't solve puzzles that open portals to Hell"'