is __index cached during luau_load?

[morgoth990]

I have added a metatable to a table like this:

int test = 0;
static int lua_device_index(lua_State* L)
{
    const char* name = luaL_checkstring(L, 2);

    if (printCallbackPtr != nullptr)
        printCallbackPtr(CPPStringToCSString(name));

    lua_pushnumber(L, test++);

    return 1;
}

static void setupMetatable()
{
    lua_newtable(L);
    luaL_newmetatable(L, "dev");

    lua_pushstring(L, "__index");
    lua_pushcfunction(L, lua_device_index);
    lua_settable(L, -3);

    lua_setreadonly(L, -1, true);
    lua_setmetatable(L, -2);

    lua_setglobal(L, "dev");
}

the goal is to call the lua_device_index every time the code is accessing the field but it seem that the c++ function is called once during luau_load.
I'm missing something? How can I change that behaviour?

[zeux]

You'll want to add dev to the list of mutable globals by specifying it via CompilerOptions::mutableGlobals

[morgoth990]

it's not working. browsing the source I see a LuauGenericSpecialGlobals fast flag in compileOrThrow but I'm not sure how to set it or if it's involved in the my problem.

[morgoth990]

Ok, solved with this

LUAU_FASTFLAG(LuauGenericSpecialGlobals)
bool CPU::LoadSource(const std::string &source)
{
    FFlag::LuauGenericSpecialGlobals.value = true;

    const char* mutableGlobals[] = { "dev", NULL };
    Luau::CompileOptions options;
    options.mutableGlobals = &mutableGlobals[0];

    std::string bytecode = Luau::compile(source, options);
...
}

[zeux]

Ah, sorry! I forgot about this. The fast flag should be removed in a couple weeks.