Re: Registry warning?

[David Engster <deng@randomsample.de>]

Ted Zlatanov writes:
> On Thu, 29 Sep 2011 08:02:01 +0200 David Engster <deng@randomsample.de> wrote: 
>
> DE> Ted Zlatanov writes:
>>> On Wed, 28 Sep 2011 09:29:33 +0200 David Engster <deng@randomsample.de> wrote: 
>
> DE> No. If you look in your mails somewhere around May, you'll see I wrote
> DE> this to you when discussing ERT tests on Emacs 22. EIEIO cannot
> DE> magically save any LISP structure (what about recursive structures, for
> DE> example?). It uses prin1 and hopes for the best, but you can provide
> DE> your own printer in the ':printer' slot.
>>> 
>>> Thanks for repeating the information, I either forgot or misunderstood
>>> it.  So can we provide a custom printer for Emacs 23.1 and older?
>
> DE> Yes, for some definition of "we" (read: not me). ;-)
>
> Is there an API for this printer?  What functions must it provide?  We
> can just reuse the old registry save/load code.

It must do what `prin1' does, minus the optional PRINTCHARFUN
argument. That means, it has to print the slot in a way that can later
be understood by `read'. See also section 3.2 of the EIEIO info:

(info "(eieio)Slot options")

-David