Re: [Chicken-users] s11n among different chicken versions

[Daishi Kato]

On 8/7/06, felix winkelmann <address@hidden> wrote:
> On 8/7/06, Daishi Kato <address@hidden> wrote:
> >
> > If the procedure ID is really re-used, the fallback procedure is never
> > called, isn't it?
>
> That's correct, unfortunately.

OK, I found another weird behavior.
Procedures of hash-tables are referenced in a dump file,
but when I run deserialize (w/ different chicken version),
the fallback is called more then once for the same ID.
I'm afraid there is a bug in backref handling with the procedure
returned by the fallback.

> >
> > If I could not find any solution to this, my final resort would be
> > editting the binary dump file to change procedure IDs.
>
> I think it would be better to write a custom version of
> "deserialize", the last few lines look like this:
>
>              (switch tag
>               ...
>                (procedure-tag
>                 (let ((id (fetch)))
>                 ;; >>>>>> do some custom processing here <<<<<<<<<<<
>                   (cond ((##core#inline "set_procedure_ptr" x 
> (##sys#make-c-string id))
>                          (fetchslots x 1) )
>                         (fallback
>                          (let ((proc (fallback id)))
>                            (vector-set! backrefs r proc)
>                            proc) )
>                         (else (error 'deserialize "unable to deserialize 
> procedure - no
> table entry found" id))) ) )
>                (else (error 'deserialize "invalid tag" tag)) ) ) ) ) ) )
>     (fetch) ) )
>
> It shouldn't be to hard to add some hook there to do any custom
> handling of specific IDs. But, again, it's slippy terrain you're moving
> on.

I understand it's slippy, but I also think it's useful.
Isn't it possible to add a trap at "do some custom processing here"
that calls an optional procedure, just like the fallback procedure,
so that I don't need to modify the s11n code?
In this case, it is desired to pass not only a procedure ID but also
the lambda info that is shown when you run chicken-dump.

I hope this makes sense.
Daishi