Re: Lisp object that refers to a C struct

[Eli Zaretskii]

> From: Stefan Monnier <address@hidden>
> Cc: address@hidden
> Date: Mon, 15 Oct 2012 21:07:21 -0400
> 
> > There's Lisp_Save_Value, which looks very promising,
> 
> Lisp_Save_Value is a Lisp_Misc.
> 
> > but why does its documentation say it's for record_unwind_protect?
> > Is there anything in it which would preclude its use
> > outside unwinding?
> 
> It doesn't look very pretty when printed, so it's generally better not
> to expose it to users too much.  If your value will usually not be
> visible to Elisp code, then Lisp_Save_Value is perfectly fine.

OK.

> Otherwise, better define your own type so that its printed
> representation can be more helpful, indicating what it's used for

How do I define my own type?  In particular, what to do with gcmarkbit
in Lisp_Misc?

> (I presume it's for a file-watch-descriptor).

Yes.