GNU bug report logs - #78798
bibtex-font-lock-url-regexp should re-eval after setting bibtex-generate-url-list

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Package: emacs;

Reported by: MAN ONE <pRoMMMModE <at> outlook.com>

Date: Sun, 15 Jun 2025 12:09:02 UTC

Severity: normal

Done: Eli Zaretskii <eliz <at> gnu.org>

Bug is archived. No further changes may be made.

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Message #14 received at 78798 <at> debbugs.gnu.org (full text, mbox):

From: Roland Winkler <winkler <at> gnu.org>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 78798 <at> debbugs.gnu.org, Stefan Monnier <monnier <at> iro.umontreal.ca>,
 MAN ONE <pRoMMMModE <at> outlook.com>
Subject: Re: bug#78798: bibtex-font-lock-url-regexp should re-eval after
 setting bibtex-generate-url-list
Date: Tue, 08 Jul 2025 11:46:34 -0500

On Wed, Jul 02 2025, Eli Zaretskii wrote:
>> +  :set (lambda (symbol value)
>> +         (set-default symbol value)
>> +         (let ((fields (delete-dups (mapcar #'caar bibtex-generate-url-list))))
>> +           (set-default-toplevel-value
>> +            'bibtex-font-lock-url-regexp
>> +            ;; Assume that field names begin at the beginning of a line.
>> +            (concat "^[ \t]*"
>> +                    (regexp-opt fields 'paren)
>> +                    "[ \t\n]*=[ \t\n]*")))))

Small thing: What is the purpose of the intermediate let-binding?

The elisp manual says about setfunctions:

     If you specify this keyword, the variable’s documentation string
     should describe how to do the same job in hand-written Lisp code,
     either by invoking SETFUNCTION directly or by using ‘setopt’.

Isn't it then cleaner to define a helper function instead of using
a lambda expression?

>> -(defvar bibtex-font-lock-url-regexp
>> -  ;; Assume that field names begin at the beginning of a line.
>> -  (concat "^[ \t]*"
>> -          (regexp-opt (delete-dups (mapcar #'caar bibtex-generate-url-list)) t)
>> -          "[ \t\n]*=[ \t\n]*")
>> +(defvar bibtex-font-lock-url-regexp nil
>>    "Regexp for `bibtex-font-lock-url' derived from `bibtex-generate-url-list'.")

I was surprised when I tested the above that it sets
bibtex-font-lock-url-regexp even if the value of
bibtex-generate-url-list is defined outside defcustom, that is,
defcustom evaluates the above setfunction even when it ignores the
standard value for bibtex-generate-url-list.  This is sensible,
but I did not find it documented anywhere.
This bug report was last modified 12 days ago.

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