Function is_null

library/LuaTypes.cpp:272–277

}

static bool is_null(lua_State *state, int val_index)
{
    return lua_isnil(state, val_index) ||
           (lua_islightuserdata(state, val_index) &&
            !lua_touserdata(state, val_index));
}

void df::pointer_identity::lua_write(lua_State *state, int fname_idx, void *ptr,
                                     const type_identity *target, int val_index)