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From: Alan Mackenzie <acm@muc.de>
To: Eli Zaretskii <eliz@gnu.org>
Cc: monnier@iro.umontreal.ca, emacs-devel@gnu.org
Subject: Re: Lisp primitives and their calling of the change hooks
Date: Sun, 7 Jan 2018 17:54:18 +0000	[thread overview]
Message-ID: <20180107175418.GD22254@ACM> (raw)
In-Reply-To: <83mv1p8vki.fsf@gnu.org>

Hello, Eli.

On Sun, Jan 07, 2018 at 18:47:41 +0200, Eli Zaretskii wrote:
> > Date: Sun, 7 Jan 2018 13:56:29 +0000
> > From: Alan Mackenzie <acm@muc.de>
> > Cc: monnier@iro.umontreal.ca, emacs-devel@gnu.org

> > > > zlib-decompress-region calls del_range, which calls the hooks.  Or am
> > > > I missing something?

> > > Yes, you're right, sorry.  There are change-hook calls for the second,
> > > deletion, part of the operation.  No hooks are called for the first
> > > part, the insertion of the decompressed text into the buffer.  So
> > > zlib-decompress-region is still not right.

> > > I'm going to take a careful look for any more such primitives, which
> > > have one balanced pair of change hook calls, yet these calls only cover
> > > part of the operation.

> > There appear to be no more such primitives.

> > Should I try to fix zlib-decompress-region?

> How do you want to fix it?  That function inserts the decompressed
> stuff, then deletes the original compressed stuff.  What do you want
> that to produce in terms of the change hooks?

IIUC, zlib-decompress-region decompresses in chunks into the gap,
expanding the gap after each chunk.

The strategy of one overarching before-change-functions followed by lots
of little after-change-functions can't really work here, since we don't
know in advance how big the region being written to is.  In fact, I think
this strategy is used only when the individual changes don't change the
buffer's size, e.g. when doing upcase-region, or
translate-region-internal.  We don't have this here.

One way of doing it would be to have a balanced pair of b/a-c-f for each
chunk of text inserted.  The other way would be having a single b/a-c-f
pair.

For reasons I can't articulate, I think the single pair of hooks would be
better; less "noisy", perhaps.  But either strategy would work well.

-- 
Alan Mackenzie (Nuremberg, Germany).



  parent reply	other threads:[~2018-01-07 17:54 UTC|newest]

Thread overview: 66+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-01-03 12:45 Lisp primitives and their calling of the change hooks Alan Mackenzie
2018-01-03 21:51 ` Stefan Monnier
2018-01-04 15:51   ` Alan Mackenzie
2018-01-04 18:16     ` Stefan Monnier
2018-01-04 21:11       ` Alan Mackenzie
2018-01-04 21:36         ` Stefan Monnier
2018-01-06 15:18           ` Alan Mackenzie
2018-01-06 15:51             ` Stefan Monnier
2018-01-06 16:18               ` Eli Zaretskii
2018-01-06 19:06                 ` Alan Mackenzie
2018-01-06 20:24               ` Alan Mackenzie
2018-01-07 11:36                 ` Alan Mackenzie
2018-01-07 11:49                   ` Eli Zaretskii
2018-01-07 12:08                     ` Alan Mackenzie
2018-01-07 13:56                       ` Alan Mackenzie
2018-01-07 15:21                         ` [SUSPECTED SPAM] " Stefan Monnier
2018-01-07 16:47                         ` Eli Zaretskii
2018-01-07 17:50                           ` Stefan Monnier
2018-01-07 17:58                             ` Eli Zaretskii
2018-01-07 19:04                               ` Stefan Monnier
2018-01-07 19:48                                 ` Alan Mackenzie
2018-01-07 19:58                                   ` Eli Zaretskii
2018-01-07 21:10                                     ` Alan Mackenzie
2018-01-08  3:41                                       ` Eli Zaretskii
2018-01-08 19:24                                         ` Alan Mackenzie
2018-01-08 21:15                                           ` Eli Zaretskii
2018-01-08 22:24                                             ` Stefan Monnier
2018-01-09  3:55                                               ` Eli Zaretskii
2018-01-09 13:30                                                 ` Stefan Monnier
2018-01-09 18:50                                                   ` Eli Zaretskii
2018-01-09 19:53                                             ` Alan Mackenzie
2018-01-09 20:05                                               ` Eli Zaretskii
2018-01-10 18:29                                                 ` Alan Mackenzie
2018-01-12 16:40                                                   ` Alan Mackenzie
2018-01-09 20:07                                               ` Stefan Monnier
2018-01-10 18:45                                                 ` Alan Mackenzie
2018-01-10 19:30                                                   ` Stefan Monnier
2018-01-10 19:48                                                     ` Alan Mackenzie
2018-01-10 20:33                                                       ` Stefan Monnier
2018-01-10 21:03                                                         ` Alan Mackenzie
2018-01-11 13:36                                                           ` Stefan Monnier
2018-01-11 17:39                                                             ` Alan Mackenzie
2018-01-11 19:35                                                               ` Stefan Monnier
2018-01-11 19:46                                                                 ` Alan Mackenzie
2018-01-11 20:15                                                                   ` Stefan Monnier
2018-01-11 21:20                                                                     ` Alan Mackenzie
2018-01-11 23:42                                                                       ` Stefan Monnier
2018-01-12 16:14                                                                         ` Alan Mackenzie
2018-01-10 22:06                                                       ` Clément Pit-Claudel
2018-01-10 22:20                                                         ` Alan Mackenzie
2018-01-08  4:29                                   ` Stefan Monnier
2018-01-07 17:54                           ` Alan Mackenzie [this message]
2018-01-07 18:05                             ` Eli Zaretskii
2018-01-05  6:55         ` Eli Zaretskii
2018-01-05 11:41           ` Alan Mackenzie
2018-01-05 13:00             ` Eli Zaretskii
2018-01-05 13:34               ` Alan Mackenzie
2018-01-05 14:08                 ` Eli Zaretskii
2018-01-05 15:54                   ` Alan Mackenzie
2018-01-05 16:50           ` Stefan Monnier
2018-01-05 17:38             ` Alan Mackenzie
2018-01-05 18:09               ` Stefan Monnier
2018-01-05 19:53             ` Eli Zaretskii
2018-01-05 22:28               ` Stefan Monnier
2018-01-06  9:05                 ` Eli Zaretskii
2018-01-06 15:26                   ` Stefan Monnier

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