From: Eli Zaretskii <eliz@gnu.org>
To: Dmitry Gutov <dgutov@yandex.ru>
Cc: monnier@iro.umontreal.ca, emacs-devel@gnu.org
Subject: Re: locked narrowing in ELisp
Date: Wed, 17 Aug 2022 17:20:02 +0300 [thread overview]
Message-ID: <83mtc3c5pp.fsf@gnu.org> (raw)
In-Reply-To: <3c4f3c87-39a1-9ee7-1ca7-384315882663@yandex.ru> (message from Dmitry Gutov on Wed, 17 Aug 2022 17:03:46 +0300)
> Date: Wed, 17 Aug 2022 17:03:46 +0300
> Cc: monnier@iro.umontreal.ca, emacs-devel@gnu.org
> From: Dmitry Gutov <dgutov@yandex.ru>
>
> On 17.08.2022 16:55, Eli Zaretskii wrote:
> >> For instance, use two overlays in the current buffer with `invisible'
> >> property rather than have the display engine refer to the new kind of
> >> narrowing bounds.
> >
> > That's a time bomb waiting to go off, because invisible text is
> > handled at a relatively high level in the display engine, and
> > otherwise the invisible property is largely ignored in Emacs.
>
> User-level features should be implementable in terms of primitives
> allowed in Lisp userland.
I don't see how this is relevant to the concern I raised. I was
talking about the effects on the display engine. It doesn't only
display, it also looks at buffer text for various purposes.
> > Moreover, it will make redisplay slower. Skipping invisible text is
> > faster than iterating through it, but it still takes time, whereas not
> > going beyond BEGV..ZV is instantaneous.
>
> Org, as one example, uses invisible text all the time. Other feature too.
And Org is indeed relatively slow when you move through a buffer which
has large parts of it hidden by invisible properties.
> > And finally, I don't think I see the benefit of this, even if it'd
> > work: you want to get rid of (save-restriction (widen)), but you are
> > willing to have to replace that with tests of overlays and invisible
> > text all over the place?
>
> No, I don't think the addition of "tests ... all over the place" will be
> needed. The display engine handles the 'invisible' property already.
>
> A number of features/commands will indeed need to know the bounds of the
> user-level narrowing (and we'll have a buffer-local variable for that),
> but that's probably it.
I don't think you realize how widespread is use of low-level
primitives and functions in user-level commands.
What you suggest is not a clean design, because it is based on
inaccurate mental model of Emacs internals. It cannot work reliably,
to the best of my knowledge.
next prev parent reply other threads:[~2022-08-17 14:20 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-16 20:18 locked narrowing in ELisp Stefan Monnier
2022-08-17 0:05 ` Dmitry Gutov
2022-08-17 0:55 ` Stefan Monnier
2022-08-17 1:00 ` Dmitry Gutov
2022-08-17 13:03 ` Stefan Monnier
2022-08-17 13:40 ` Dmitry Gutov
2022-08-17 13:55 ` Eli Zaretskii
2022-08-17 14:03 ` Dmitry Gutov
2022-08-17 14:20 ` Eli Zaretskii [this message]
2022-08-17 23:13 ` Dmitry Gutov
2022-08-18 1:58 ` Stefan Monnier
2022-08-18 21:42 ` Dmitry Gutov
2022-08-18 6:25 ` Eli Zaretskii
2022-08-18 23:10 ` Dmitry Gutov
2022-08-19 6:31 ` Eli Zaretskii
2022-08-22 0:59 ` Dmitry Gutov
2022-08-17 11:44 ` Eli Zaretskii
2022-08-17 11:54 ` Dmitry Gutov
2022-08-17 5:59 ` Po Lu
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
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=83mtc3c5pp.fsf@gnu.org \
--to=eliz@gnu.org \
--cc=dgutov@yandex.ru \
--cc=emacs-devel@gnu.org \
--cc=monnier@iro.umontreal.ca \
/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 external index
https://git.savannah.gnu.org/cgit/emacs.git
https://git.savannah.gnu.org/cgit/emacs/org-mode.git
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.