A couple of problems with new packages

[Vin Shelton]

Dear Aidan,

Thanks for the patch.

On Dec 2, 2007 6:23 PM, Aidan Kehoe <kehoea at parhasard.net> wrote:
>
>  Ar an dara lá de mí na Nollaig, scríobh Vin Shelton:
>
>  > On Dec 2, 2007 3:29 PM, Aidan Kehoe <kehoea at parhasard.net> wrote:
>  >
>  > > That's coming from my change of
>  > > http://mid.gmane.org/18252.39139.149087.844153@parhasard.net ; the 21.5 byte
>  > > compiler adds a :default keyword to custom-declare-variable calls when it
>  > > byte compiles the init value. This allows the custom UI code to present
>  > > non-byte-compiled Lisp for editing. I don't know of a way to avoid the error
>  > > entirely.
>  > >
>  > > The error should be limited to the specific case of 21.4 loading code
>  > > compiled by 21.5 where the code has complex VALUE clauses in defcustom
>  > > calls.
>  > >
>  > > Vin, would you consider adding the very last hunk of that patch to 21.4?
>  >
>  > Yes, I'll consider it, but whether or not I apply it, we must solve
>  > the problem for users of XEmacs <= 21.4.21.  Please make a suggestion
>  > so that packages built with 21.5 will work with existing 21.4
>  > installs.
>
> With a bit of further thought, the below occurs to me, which is entirely
> compatible and very ugly. Is running packages built with 21.5 on 21.4 a
> supported use case?

Yes.

> What happens if we modify 21.5's byte codes?

We try not to do that.  At the moment, it's not possible to build the
packages with the 21.4 compiler, so it's pretty important that we be
able to build the packages with 21.5 and load them into 21.4.

>
> lisp/ChangeLog addition:
>
> 2007-12-03  Aidan Kehoe  <kehoea at parhasard.net>
>
>         * bytecomp.el (byte-compile-file-form-custom-declare-variable):
>         Instead of using a keyword argument that's incompatible with 21.4,
>         modify the byte compiled init code to change the variable's
>         standard-value property itself.
>
>
> XEmacs Trunk source patch:
> Diff command:   cvs -q diff -Nu
> Files affected: lisp/bytecomp.el
> ===================================================================
> RCS
>
> Index: lisp/bytecomp.el
> ===================================================================
> RCS file: /pack/xemacscvs/XEmacs/xemacs/lisp/bytecomp.el,v
> retrieving revision 1.22
> diff -u -u -r1.22 bytecomp.el
> --- lisp/bytecomp.el    2007/12/01 13:40:07     1.22
> +++ lisp/bytecomp.el    2007/12/02 23:19:18
> @@ -2405,10 +2405,17 @@
>         ;; And save a value to be examined in the custom UI, if that differs
>         ;; from the init value.
>         (unless (equal to-examine (car-safe (cdr (third form))))
> -         (setf (nthcdr 4 form) (nconc
> -                                (list :default
> -                                      (list 'quote to-examine))
> -                                (nthcdr 4 form)))))
> +         (setcdr (third form)
> +                 (list (byte-compile-top-level
> +                        ;; This is ugly. custom-declare-variable errors if
> +                        ;; it's passed a keyword it doesn't know about, and
> +                        ;; so to make this code run on 21.4, we add code to
> +                        ;; modify the standard-value property to the
> +                        ;; byte-compiled value for DEFAULT.
> +                        `(prog2 (put ,(second form) 'standard-value
> +                                     '(,to-examine))
> +                          ,to-examine)
> +                        nil 'file)))))
>      form))
>
>  ;;;###autoload


Thanks, I'll examine the patch and try it out.  At first blush, I
agree with you: it's ugly :-) .

Regards,
  Vin