From: Jeff Norden <jnorden@tntech.edu>
To: Ihor Radchenko <yantar92@gmail.com>
Cc: emacs-devel@gnu.org
Subject: Re: A question about overlays and performance.
Date: Thu, 30 Jul 2020 13:21:45 -0500 [thread overview]
Message-ID: <fdbljw6eyu.fsf@norden.tntech.edu> (raw)
In-Reply-To: <87pn8f3x5m.fsf@localhost> (message from Ihor Radchenko on Wed, 29 Jul 2020 09:52:37 +0800)
>> ... inclined to agree with Stefan's opinion about indirect buffers.
> Another common use is narrowing to subtrees, so that you have two
> buffers with different narrowing for the same org file. It is not
> possible within a single buffer, as far I as know.
So the org case for indirect buffers is messier than I had imagined, which
shouldn't surprise me. I'm a very casual user of org - just as an
alternative to outline-mode for the cycling and the intuitive use of the
tab key.
> What do you mean by "exactly the opposite"?
I was working on changing some text-property based code to use overlays
instead, but I'm having second thoughts. Overlays simplified some things,
but not as much as I thought they would. I also ran into a couple of snags:
1) There don't seem to be 'char-property' versions of text-property-any or
text-property-not-all. I guess you could do this in lisp with a loop using
next-char-property-change, but that works against my original goal of
simplifying things.
2) A simple option that you have for protecting hidden text when using
text-properties is to temporarily mark it as read-only, e.g.:
(add-text-properties beg end '(invisible t read-only t))
Of course, you need to make sure you remove both properties when you
un-hide (and take into account that you are now changing read-only text).
It also means that you can't kill or delete a region that contains hidden
text without un-hiding it first. That may or may not be a good thing,
depending on your perspective. There might also be other side-effects that
I'm not thinking of right now.
---
I just looked at org a bit more and discovered org-catch-invisible-edits.
It works, in part, because org re-binds the keys that usually call
delete-char and delete-backward-char. I tried it, and found that even with
catch-invisible-edits set to 'error, if you put the cursor right before an
ellipsis and type M-d, the first word in the hidden text is silently
deleted. I wouldn't say this is a bug or problem, since it is hard to
imagine someone doing that accidentally. I just thought it was interesting.
Best regards,
-Jeff
next prev parent reply other threads:[~2020-07-30 18:21 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-25 16:40 A question about overlays and performance Jeff Norden
2020-07-25 16:53 ` Eli Zaretskii
2020-07-25 17:24 ` Jeff Norden
2020-07-25 17:29 ` Eli Zaretskii
2020-07-26 1:33 ` Ihor Radchenko
2020-07-26 13:56 ` Eli Zaretskii
2020-07-26 14:19 ` Ihor Radchenko
2020-07-26 14:44 ` Stefan Monnier
2020-07-27 11:20 ` Ihor Radchenko
2020-07-28 16:43 ` Jeff Norden
2020-07-28 16:58 ` Yuan Fu
2020-07-28 17:05 ` Eric Abrahamsen
2020-07-29 1:52 ` Ihor Radchenko
2020-07-30 18:21 ` Jeff Norden [this message]
2020-07-28 23:53 ` Juri Linkov
2020-07-29 1:36 ` Ihor Radchenko
2020-07-30 23:04 ` Juri Linkov
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