On 1 May 2018 at 22:36, Laurent FAILLIE <l_faillie@yahoo.com> wrote: > Hello, > > Reading example in https://www.lua.org/pil/28.2.html, I guessed that > luaL_checkudata() only return a NULL pointer if the argument doesn't match > an user data of the given type. > But unfortunately, it raise a fatal error : try luaL_testudata() [1] [1]: https://www.lua.org/manual/5.3/manual.html#luaL_testudata