From: Lars Ingebrigtsen <larsi@gnus.org>
To: Oleh Krehel <ohwoeowho@gmail.com>
Cc: 20153@debbugs.gnu.org
Subject: bug#20153: 24.4.91; destructive add-face-text-property and string deep copying
Date: Wed, 09 Oct 2019 04:25:04 +0200 [thread overview]
Message-ID: <87a7aawt8f.fsf@gnus.org> (raw)
In-Reply-To: <87bnjnyhtb.fsf@gmail.com> (Oleh Krehel's message of "Fri, 20 Mar 2015 13:28:00 +0100")
Oleh Krehel <ohwoeowho@gmail.com> writes:
> Here's an example of what I'm trying to do:
>
> (setq test-str-1
> #(";; This `is' a test"
> 0 3 (fontified nil face font-lock-comment-delimiter-face)
> 3 9 (fontified nil face font-lock-comment-face)
> 9 11 (fontified nil face (font-lock-constant-face font-lock-comment-face))
> 11 19 (fontified nil face font-lock-comment-face)))
> (setq test-str-2 (concat test-str-1))
> (add-face-text-property 0 (length test-str-2) 'foobar t test-str-2)
>
> I would like to modify `test-str-2' without touching `test-str-1'.
> For that, I either need `add-face-text-property' to be non-destructive,
> either w.r.t. the string or at least w.r.t. the properties of the
> string, or a way to deep-copy a string.
It's this code (in add_properties):
/* The previous value is a list, so prepend (or
append) the new value to this list. */
if (set_type == TEXT_PROPERTY_PREPEND)
Fsetcar (this_cdr, Fcons (val1, Fcar (this_cdr)));
else
nconc2 (Fcar (this_cdr), list1 (val1));
But changing that would have pretty far-reaching consequences. I wonder
whether instead Fadd_face_text_property should just (when called with a
string parameter) just copy the `face' property list first? That should
avoid the problem and not lead to any general slowdown.
--
(domestic pets only, the antidote for overdose, milk.)
bloggy blog: http://lars.ingebrigtsen.no
next prev parent reply other threads:[~2019-10-09 2:25 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-20 12:28 bug#20153: 24.4.91; destructive add-face-text-property and string deep copying Oleh Krehel
2019-10-09 2:25 ` Lars Ingebrigtsen [this message]
2019-10-09 3:04 ` Lars Ingebrigtsen
2019-10-09 8:24 ` Oleh Krehel
2019-10-09 17:10 ` Eli Zaretskii
2019-10-09 17:45 ` Lars Ingebrigtsen
2019-10-09 18:06 ` Eli Zaretskii
2019-10-09 18:09 ` Lars Ingebrigtsen
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