struct luaTest
{
    int aaa;
    char bbb;
    float ccc;
};

int l_set(lua_State * L)
{
    luaTest * data = (luaTest*)luaL_checkudata(L, 1, "userdata");
    const c8 * key = luaL_checkstring(L, 2);

    if(strcmp(key, "aaa") == 0)
        data->a = luaL_checkint(L, 3);
    if(strcmp(key, "bbb") == 0)
        data->b = luaL_checkint(L, 3);
    if(strcmp(key, "ccc") == 0)
        data->c = luaL_checknumber(L, 3);

    return 0;
}