bug#44647: 27.1.50; `bibtex-contline-indentation' doesn't work as file local variable

[Teemu Likonen]

* 2020-11-14 23:27:41+02, Teemu Likonen wrote:
> * 2020-11-14 23:18:16+02, Teemu Likonen wrote:
>> Variable bibtex-contline-indentation does not work as file local
>> variable. The reason is that bibtex-mode command initializes variable
>> fill-prefix before the possible file local variable is available. It
>> gets always the global value of bibtex-contline-indentation.
>>
>> This can be fixed by locally let-binding fill-prefix every time in the
>> relevant filling function. Patch for that is attached.
>
> See: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=44647

I'll add one example. Currently if we want to use file or directory
local variable to define bibtex indentation we must do use variable
bibtex-text-indentation for normal field value indentation and then use
fill-prefix with spaces to define the indentation for continuation
lines:

    ;; .dir-locals.el
    ((bibtex-mode . ((bibtex-text-indentation . 20)
                     (fill-prefix . "                     ")))) ; 21 spaces

Quite obviously more user-friendly way would be this:

    ;; .dir-locals.el
    ((bibtex-mode . ((bibtex-text-indentation . 20)
                     (bibtex-contline-indentation . 21))))

My patch does this. It let-binds fill-prefix every time and initializes
its value by using the (possibly buffer local) value of
bibtex-contline-indentation.

Here is inline version of the patch so that it is easier to read in
debbugs.gnu.org page.

From a776cae4fcd34987e30b6eab3df45bd2ae66fbd9 Mon Sep 17 00:00:00 2001
From: Teemu Likonen <tlikonen@iki.fi>
Date: Sat, 14 Nov 2020 22:53:18 +0200
Subject: [PATCH] Make `bibtex-contline-indentation' work as file local
 variable

* lisp/textmodes/bibtex.el (bibtex-mode): Don't make fill-prefix a
buffer local variable. It would use the global value, not possible
file local variable.
* lisp/textmodes/bibtex.el (bibtex-fill-field-bounds): Let-bind
fill-prefix variable locally (and dynamically) for use with filling
bibtex fields. The variable is initialized every time by using the
current value of bibtex-contline-indentation variable.
---
 lisp/textmodes/bibtex.el | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/lisp/textmodes/bibtex.el b/lisp/textmodes/bibtex.el
index fcf63ed5ec..151dca6fab 100644
--- a/lisp/textmodes/bibtex.el
+++ b/lisp/textmodes/bibtex.el
@@ -3442,8 +3442,6 @@ bibtex-mode
   (set (make-local-variable 'defun-prompt-regexp) "^[ \t]*@[[:alnum:]]+[ \t]*")
   (set (make-local-variable 'outline-regexp) "[ \t]*@")
   (set (make-local-variable 'fill-paragraph-function) #'bibtex-fill-field)
-  (set (make-local-variable 'fill-prefix)
-       (make-string (+ bibtex-entry-offset bibtex-contline-indentation) ?\s))
   (set (make-local-variable 'font-lock-defaults)
        '(bibtex-font-lock-keywords
          nil t ((?$ . "\"")
@@ -4902,7 +4900,10 @@ bibtex-fill-field-bounds
   "Fill BibTeX field delimited by BOUNDS.
 If JUSTIFY is non-nil justify as well.
 If optional arg MOVE is non-nil move point to end of field."
-  (let ((end-field (copy-marker (bibtex-end-of-field bounds))))
+  (let ((end-field (copy-marker (bibtex-end-of-field bounds)))
+        (fill-prefix (make-string (+ bibtex-entry-offset
+                                     bibtex-contline-indentation)
+                                  ?\s)))
     (if (not justify)
         (goto-char (bibtex-start-of-text-in-field bounds))
       (goto-char (bibtex-start-of-field bounds))
-- 
2.20.1

-- 
/// Teemu Likonen - .-.. https://www.iki.fi/tlikonen/
// OpenPGP: 4E1055DC84E9DFF613D78557719D69D324539450

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