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From: Stefan Monnier <monnier@iro.umontreal.ca>
To: Drew Adams <drew.adams@oracle.com>
Cc: eliz@gnu.org, rms@gnu.org, emacs-devel@gnu.org
Subject: Re: Overlay insertion types, markers, etc.
Date: Sun, 17 Nov 2019 10:55:54 -0500	[thread overview]
Message-ID: <jwvblta8pug.fsf-monnier+emacs@gnu.org> (raw)
In-Reply-To: <29c934d3-712c-414e-b4aa-9ed8f3c609a2@default> (Drew Adams's message of "Sat, 16 Nov 2019 18:26:39 -0800 (PST)")

> 4. Can you retrieve the markers that are "used by"
>    an overlay, i.e., as markers?

No, you can't, and you shouldn't be able to: it's an implementation
detail, that may change in the future (IIUC the `noverlays` branch
indeed makes this change as part of a rewrite which tries to eliminate
some algorithmic complexity problems in the overlay code).

Also it would introduce all kinds of extra work:
- when an overlay is moved, the redisplay code is told about it, whereas
  no redisplay is normally caused by moving a marker, so we'd need to
  figure out what to do when an "overlay-owned" marker is moved.
- the user could now move the start-marker of an overlay to another buffer
  than the end-marker
- the user could now move the end-marker of an overlay before the
  start-marker (this can already happen but only in very specific
  cases, so we'd have to handle it in more cases).
- ...


        Stefan




  reply	other threads:[~2019-11-17 15:55 UTC|newest]

Thread overview: 13+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <<<20c74b83-6272-44e9-b4ac-829fd4cd0143@default>
     [not found] ` <<<83lfsh2zvf.fsf@gnu.org>
     [not found]   ` <<a2de3d64-2fb6-41e4-aabe-0be2ec404478@default>
     [not found]     ` <<83v9rl12t1.fsf@gnu.org>
2019-11-15 17:32       ` Overlay insertion types, markers, etc Drew Adams
2019-11-17  2:15         ` Richard Stallman
2019-11-17  2:26           ` Drew Adams
2019-11-17 15:55             ` Stefan Monnier [this message]
2019-11-17 17:35               ` Drew Adams
2019-11-20 16:17             ` Richard Stallman
2019-11-20 17:33               ` Eli Zaretskii
2019-11-20 17:38               ` Drew Adams
     [not found] <<20c74b83-6272-44e9-b4ac-829fd4cd0143@default>
     [not found] ` <<83lfsh2zvf.fsf@gnu.org>
2019-11-15 16:54   ` Drew Adams
2019-11-15 17:12     ` Eli Zaretskii
2019-11-12  0:09 Drew Adams
2019-11-13 15:36 ` Drew Adams
2019-11-15 10:33 ` Eli Zaretskii

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