#define SOL_ALL_SAFETIES_ON 1 #include #include int main() { sol::state lua; lua["bark"] = 50; sol::optional x = lua["bark"]; // x will have a value if (x) { return -1; } else { std::cout << "x has no value, as expected" << std::endl; } lua["bark"] = sol::lua_nil; sol::optional y = lua["bark"]; // y will not have a value if (x) { return -1; } else { std::cout << "y has no value, as expected" << std::endl; } return 0; }