bug#74637: [PATCH] Make view-read-only behave like view-file

bug#74637: [PATCH] Make view-read-only behave like view-file

[Björn Bidar via Bug reports for GNU Emacs, the Swiss army knife of text editors]

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Tags: patch


Make view-mode behave like when called in view-file when entered because
`view-read-only' is true on a file which is not writable.
The change makes the view-read-only behave better on files which are
not writable. 
Now it makes Emacs behave more like less on these files.



In GNU Emacs 31.0.50 (build 1, x86_64-suse-linux-gnu, GTK+ Version
3.24.43, cairo version 1.18.2)
Repository revision: eee0ed8442aa78320a3e578ab290df145fb49624
Repository branch: master
Windowing system distributor 'The X.Org Foundation', version 11.0.12101014
System Description: openSUSE Tumbleweed

Configured using:
 'configure --disable-build-details --without-pop --with-mailutils
 --without-hesiod --with-gameuser=:games --with-kerberos
 --with-kerberos5 --with-file-notification=inotify --with-modules
 --enable-autodepend --enable-link-time-optimization --prefix=/usr
 --mandir=/usr/share/man --infodir=/usr/share/info --datadir=/usr/share
 --localstatedir=/var --sharedstatedir=/var/lib
 --libexecdir=/usr/libexec --with-file-notification=yes
 --libdir=/usr/lib64 --with-native-compilation=aot
 --enable-locallisppath=/usr/share/emacs/31.0.50/site-lisp:/usr/share/emacs/site-lisp
 --with-x --with-xim --with-sound --with-xpm --with-jpeg --with-tiff
 --with-gif --with-png --with-rsvg --with-dbus --with-xft --without-gpm
 --with-tree-sitter --with-x-toolkit=gtk --without-pgtk
 --with-toolkit-scroll-bars --x-includes=/usr/include
 --x-libraries=/usr/lib64 --with-libotf --with-m17n-flt --with-cairo
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 build_alias=x86_64-suse-linux 'CC=sccache cc' 'CFLAGS=-O2 -Wall
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From d77d0880871061820b1cdf61f1d74f2a7e5224aa Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Bj=C3=B6rn=20Bidar?= <bjorn.bidar@thaodan.de>
Date: Sun, 1 Dec 2024 22:22:24 +0200
Subject: [PATCH] Make view-read-only behave like view-file

Make view-mode also behave like less when entered through the
view-read-only option similarly as done in in
'1997-06-14 "Make view mode more similar to `less'' (ab7782fc244).
* lisp/files.el (after-find-file):
When opening a file which is read only and `view-read-only' is true
leave view-mode with `kill-buffer-if-not-modified'.
* lisp/view.el (view-mode): Document new behavior.
---
 lisp/files.el | 2 +-
 lisp/view.el  | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/lisp/files.el b/lisp/files.el
index a65bc4a4ea2..2f062b45daf 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -2874,7 +2874,7 @@ after-find-file
     (when (and buffer-read-only
 	       view-read-only
 	       (not (eq (get major-mode 'mode-class) 'special)))
-      (view-mode-enter))
+      (view-mode-enter nil 'kill-buffer-if-not-modified))
     (run-hooks 'find-file-hook)))
 
 (define-obsolete-function-alias 'report-errors 'with-demoted-errors "25.1")
diff --git a/lisp/view.el b/lisp/view.el
index 2ac7479739f..422d8a1f537 100644
--- a/lisp/view.el
+++ b/lisp/view.el
@@ -416,7 +416,7 @@ view-mode
 The effect of \\[View-leave], \\[View-quit] and \\[View-kill-and-leave] depends on how view-mode was entered.  If it was
 entered by view-file, view-file-other-window, view-file-other-frame, or
 \\[dired-view-file] \(\\[view-file], \\[view-file-other-window],
-\\[view-file-other-frame], or the Dired mode v command),
+\\[view-file-other-frame], `view-read-only', or the Dired mode v command),
 then \\[View-quit] will try to kill the current buffer.
 If view-mode was entered from another buffer, by \\[view-buffer],
 \\[view-buffer-other-window], \\[view-buffer-other frame], \\[view-file],
-- 
2.45.2

bug#74637: [PATCH] Make view-read-only behave like view-file

[Eli Zaretskii]

> Date: Sun, 01 Dec 2024 22:40:16 +0200
> From:  Björn Bidar via "Bug reports for GNU Emacs,
>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> 
> Make view-mode behave like when called in view-file when entered because
> `view-read-only' is true on a file which is not writable.
> The change makes the view-read-only behave better on files which are
> not writable. 
> Now it makes Emacs behave more like less on these files.

That's an incompatible behavior change.  Is that justified?  How can
we be sure that everyone agrees with your interpretation of this mode?

bug#74637: [PATCH] Make view-read-only behave like view-file

[Björn Bidar via Bug reports for GNU Emacs, the Swiss army knife of text editors]

Eli Zaretskii <eliz@gnu.org> writes:

>> Date: Sun, 01 Dec 2024 22:40:16 +0200
>> From:  Björn Bidar via "Bug reports for GNU Emacs,
>>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
>> 
>> Make view-mode behave like when called in view-file when entered because
>> `view-read-only' is true on a file which is not writable.
>> The change makes the view-read-only behave better on files which are
>> not writable. 
>> Now it makes Emacs behave more like less on these files.
>
> That's an incompatible behavior change.  Is that justified?  How can
> we be sure that everyone agrees with your interpretation of this mode?

All other view-file like modes behave like this, you view the file and
leave the file with q.

But even going with that point: You open a file file which isn't
writable. Once you hit q the window is quit and the buffer is buried.
What do you do now next time you visit that file?
The buffer was buried, view-mode isn't active anymore, you would have
to activate view-mode again to go where you left off.

If you would want to edit the file the you visited this way you would
have not pressed q but e to exit view mode and the proceeded to exit
read-only-mode and edit the file.

bug#74637: [PATCH] Make view-read-only behave like view-file

[Eli Zaretskii]

> From: Björn Bidar <bjorn.bidar@thaodan.de>
> Cc: 74637@debbugs.gnu.org
> Date: Mon, 02 Dec 2024 20:08:46 +0200
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> Date: Sun, 01 Dec 2024 22:40:16 +0200
> >> From:  Björn Bidar via "Bug reports for GNU Emacs,
> >>  the Swiss army knife of text editors" <bug-gnu-emacs@gnu.org>
> >> 
> >> Make view-mode behave like when called in view-file when entered because
> >> `view-read-only' is true on a file which is not writable.
> >> The change makes the view-read-only behave better on files which are
> >> not writable. 
> >> Now it makes Emacs behave more like less on these files.
> >
> > That's an incompatible behavior change.  Is that justified?  How can
> > we be sure that everyone agrees with your interpretation of this mode?
> 
> All other view-file like modes behave like this, you view the file and
> leave the file with q.

That doesn't change the fact that view-mode didn't behave like that,
until now.

> But even going with that point: You open a file file which isn't
> writable. Once you hit q the window is quit and the buffer is buried.
> What do you do now next time you visit that file?
> The buffer was buried, view-mode isn't active anymore, you would have
> to activate view-mode again to go where you left off.
> 
> If you would want to edit the file the you visited this way you would
> have not pressed q but e to exit view mode and the proceeded to exit
> read-only-mode and edit the file.

What about entering view-mode by typing "C-x C-q" in a buffer whose
file is writable?  Why should we kill the buffer when the user turns
off view-mode in that file's buffer?