* bug#23255: Running (prettify-symbols-mode) twice adds two entries to font-lock-keywords
@ 2016-04-09 19:00 Clément Pit--Claudel
2019-07-28 20:15 ` Lars Ingebrigtsen
0 siblings, 1 reply; 2+ messages in thread
From: Clément Pit--Claudel @ 2016-04-09 19:00 UTC (permalink / raw)
To: 23255
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Changing the lists of symbols prettified by prettify-symbols-mode is more tricky than it should be; I think this is a bug in prettify-symbols-mode. Here is a test case:
(with-current-buffer (get-buffer-create "fl")
(erase-buffer)
(emacs-lisp-mode)
(prettify-symbols-mode -1)
(setq prettify-symbols-alist '(("A" . ?B)))
(prettify-symbols-mode)
(setq prettify-symbols-alist '(("A" . ?C)))
(prettify-symbols-mode)
(insert "A A A")
(pop-to-buffer (current-buffer)))
Looking at this code, I expect “C C C” to be shown. Yet it's not the case; instead, “B B B” is shown.
On the other hand, this works:
(with-current-buffer (get-buffer-create "fl")
(erase-buffer)
(emacs-lisp-mode)
(prettify-symbols-mode -1)
(setq prettify-symbols-alist '(("A" . ?B)))
(prettify-symbols-mode)
(prettify-symbols-mode -1)
(setq prettify-symbols-alist '(("A" . ?C)))
(prettify-symbols-mode)
(insert "A A A")
(pop-to-buffer (current-buffer)))
I think the line indicated by !!! in the following code sample is wrong:
(define-minor-mode prettify-symbols-mode
(...)
(if prettify-symbols-mode
;; Turn on
(when (setq prettify-symbols--keywords (prettify-symbols--make-keywords))
(font-lock-add-keywords nil prettify-symbols--keywords) ;; !!! HERE
(setq-local font-lock-extra-managed-props
(append font-lock-extra-managed-props
'(composition
prettify-symbols-start
prettify-symbols-end)))
(when prettify-symbols-unprettify-at-point
(add-hook 'post-command-hook
#'prettify-symbols--post-command-hook nil t))
(font-lock-flush))
Indeed, turning on prettify-symbols-mode twice in a row causes two entries to be added to font-lock-add-keywords. This is not an issue in general, except if one changes prettify-symbols-alist between two calls. In that case font-lock-keywords gets two distinct entries for prettify-symbols, and the second one is ignored.
The proposed fix is to move the following snippet up, so that it runs in all cases, instead of just running when prettify-symbols-mode is turned off.
(when prettify-symbols--keywords
(font-lock-remove-keywords nil prettify-symbols--keywords)
(setq prettify-symbols--keywords nil))
Cheers,
Clément.
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^ permalink raw reply [flat|nested] 2+ messages in thread
* bug#23255: Running (prettify-symbols-mode) twice adds two entries to font-lock-keywords
2016-04-09 19:00 bug#23255: Running (prettify-symbols-mode) twice adds two entries to font-lock-keywords Clément Pit--Claudel
@ 2019-07-28 20:15 ` Lars Ingebrigtsen
0 siblings, 0 replies; 2+ messages in thread
From: Lars Ingebrigtsen @ 2019-07-28 20:15 UTC (permalink / raw)
To: Clément Pit--Claudel; +Cc: 23255
Clément Pit--Claudel <clement.pitclaudel@live.com> writes:
> The proposed fix is to move the following snippet up, so that it runs
> in all cases, instead of just running when prettify-symbols-mode is
> turned off.
>
> (when prettify-symbols--keywords
> (font-lock-remove-keywords nil prettify-symbols--keywords)
> (setq prettify-symbols--keywords nil))
Makes sense. I've now done this on the trunk.
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
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2016-04-09 19:00 bug#23255: Running (prettify-symbols-mode) twice adds two entries to font-lock-keywords Clément Pit--Claudel
2019-07-28 20:15 ` Lars Ingebrigtsen
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