From: Chong Yidong <cyd@stupidchicken.com>
To: bug-gnu-emacs@gnu.org
Subject: Re: two display bugs involving interactions between after-string and display properties of adjacent overlays
Date: Fri, 29 Feb 2008 13:27:47 -0500 [thread overview]
Message-ID: <87ve47bot8.fsf@stupidchicken.com> (raw)
In-Reply-To: 86k5pi9wrg.fsf@macs.hw.ac.uk
Joe Wells <jbw@macs.hw.ac.uk> writes:
> BUG #2: An overlay's display property and after-string property are
> not displayed if an immediately following overlay shares the same Lisp
> string as its display property. (Using two distinct display strings
> with identical contents works around the bug.)
>
> Reproduce with this expression:
>
> (test-in-fresh-buffer-and-window
> (insert "ABCD")
> (let ((o1 (make-overlay 2 3))
> (o2 (make-overlay 3 4))
> (s #1=" "))
> (overlay-put o1 'after-string "1")
> (overlay-put o1 'display #1#)
> (overlay-put o2 'display #1#)))
>
> The above expression should display “A 1 D”.
> The above expression wrongly actually displays “A D”.
This occurs because, as stated in the Emacs Lisp manual, all
consecutive characters that have the same Lisp object as their
`display' property are replaced as a single unit. In this case, it's
somewhat ambiguous what the behavior should be, but after looking at
the code I think the behavior you suggest would be much more difficult
to implement (and slower) than the current behavior.
Furthermore, you can trivially obtain the behavior you want by making
a copy of the string using copy-sequence, so that the two display
strings are different Lisp objects.
Therefore, let's leave this alone.
Thanks for the report, however.
prev parent reply other threads:[~2008-02-29 18:27 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-10-20 5:32 two display bugs involving interactions between after-string and display properties of adjacent overlays Joe Wells
2007-10-20 5:43 ` Joe Wells
2008-02-29 3:12 ` Chong Yidong
2008-02-29 18:27 ` Chong Yidong [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
List information: https://www.gnu.org/software/emacs/
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=87ve47bot8.fsf@stupidchicken.com \
--to=cyd@stupidchicken.com \
--cc=bug-gnu-emacs@gnu.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
Code repositories for project(s) associated with this public inbox
https://git.savannah.gnu.org/cgit/emacs.git
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).