bug#61652: 28.2; Read-only mode and View mode

bug#61652: 28.2; Read-only mode and View mode

[Bernd Rellermeyer]

I have the following scenario:

1. View a buffer in View mode.
2. Turn off Read-Only mode, e.g. by pressing `C-x C-q`.
3. Turn on Read-Only mode and View mode again, eg. by pressing `C-x
C-q`-
4. Exit View mode by `View-exit`, e.g. by pressing `e`.

Now the buffer is in Read-Only mode. In my opinion it should be
writable. The reason is the variable `view-old-buffer-read-only`, which
is set on entering View mode (`view--enable`) to the (old) value of
`buffer-read-only`. But in my scenario, the value of `buffer-read-only`
is already the new one, as set in `read-only-mode`.

I think the solution is to reset `read-only-mode` to nil in the specific
branch of `read-only-mode` and depend on the fact that it is set to t in
`view--enable`:

```
  (cond
   ((and (not buffer-read-only) view-mode)
    (View-exit-and-edit)
    (setq-local view-read-only t))		; Must leave view mode.
   ((and buffer-read-only view-read-only
         ;; If view-mode is already active, `view-mode-enter' is a nop.
         (not view-mode)
         (not (eq (get major-mode 'mode-class) 'special)))
    (setq buffer-read-only nil)
    (view-mode-enter))))
```


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bug#61652: 28.2; Read-only mode and View mode

[Eli Zaretskii]

> From: Bernd Rellermeyer <bernd.rellermeyer@t-online.de>
> Date: Mon, 20 Feb 2023 09:41:33 +0100
> 
> 
> I have the following scenario:
> 
> 1. View a buffer in View mode.
> 2. Turn off Read-Only mode, e.g. by pressing `C-x C-q`.
> 3. Turn on Read-Only mode and View mode again, eg. by pressing `C-x
> C-q`-
> 4. Exit View mode by `View-exit`, e.g. by pressing `e`.
> 
> Now the buffer is in Read-Only mode. In my opinion it should be
> writable. The reason is the variable `view-old-buffer-read-only`, which
> is set on entering View mode (`view--enable`) to the (old) value of
> `buffer-read-only`. But in my scenario, the value of `buffer-read-only`
> is already the new one, as set in `read-only-mode`.

If the buffer is already read-only when you enter View mode, why
should we reset read-only when exiting View mode?  We are trying to
leave the buffer as we found it, which in this case is read-only.

Or what am I missing?

bug#61652: 28.2; Read-only mode and View mode

[Bernd Rellermeyer]

In step 3, View mode is entered implicitly, because `view-read-only` is non-nil. From the user perspective it is only one command. I.e. the user just turns off and on Read-only mode. That means the user enters View mode vie Read-Only mode from a writable buffer. I think this should not alter the behavior of `View-exit` and after calling `View-exit` he should be in a writable buffer. Or am I wrong?

> Am 20.02.2023 um 15:42 schrieb Eli Zaretskii <eliz@gnu.org>:
> 
>> From: Bernd Rellermeyer <bernd.rellermeyer@t-online.de>
>> Date: Mon, 20 Feb 2023 09:41:33 +0100
>> 
>> 
>> I have the following scenario:
>> 
>> 1. View a buffer in View mode.
>> 2. Turn off Read-Only mode, e.g. by pressing `C-x C-q`.
>> 3. Turn on Read-Only mode and View mode again, eg. by pressing `C-x
>> C-q`-
>> 4. Exit View mode by `View-exit`, e.g. by pressing `e`.
>> 
>> Now the buffer is in Read-Only mode. In my opinion it should be
>> writable. The reason is the variable `view-old-buffer-read-only`, which
>> is set on entering View mode (`view--enable`) to the (old) value of
>> `buffer-read-only`. But in my scenario, the value of `buffer-read-only`
>> is already the new one, as set in `read-only-mode`.
> 
> If the buffer is already read-only when you enter View mode, why
> should we reset read-only when exiting View mode?  We are trying to
> leave the buffer as we found it, which in this case is read-only.
> 
> Or what am I missing?

bug#61652: 28.2; Read-only mode and View mode

[Eli Zaretskii]

> From: Bernd Rellermeyer <bernd.rellermeyer@t-online.de>
> Date: Tue, 21 Feb 2023 13:46:50 +0100
> Cc: 61652@debbugs.gnu.org
> 
> In step 3, View mode is entered implicitly, because `view-read-only` is non-nil. From the user perspective it is only one command. I.e. the user just turns off and on Read-only mode. That means the user enters View mode vie Read-Only mode from a writable buffer. I think this should not alter the behavior of `View-exit` and after calling `View-exit` he should be in a writable buffer. Or am I wrong?

I'm not sure I agree with your interpretation.

Does anyone else have an opinion?

bug#61652: 28.2; Read-only mode and View mode

[Stefan Kangas]

Eli Zaretskii <eliz@gnu.org> writes:

>> From: Bernd Rellermeyer <bernd.rellermeyer@t-online.de>
>> Date: Tue, 21 Feb 2023 13:46:50 +0100
>> Cc: 61652@debbugs.gnu.org
>>
>> In step 3, View mode is entered implicitly, because `view-read-only` is
>> non-nil. From the user perspective it is only one command. I.e. the user just
>> turns off and on Read-only mode. That means the user enters View mode vie
>> Read-Only mode from a writable buffer. I think this should not alter the
>> behavior of `View-exit` and after calling `View-exit` he should be in a
>> writable buffer. Or am I wrong?
>
> I'm not sure I agree with your interpretation.
>
> Does anyone else have an opinion?

I don't think I agree either.  Once the user starts changing
read-only-mode, I think disabling it when leaving view-mode would be
surprising.

In any case, leaving it as read-only is only a minor annoyance.
Changing it to read-write means the user can suddenly start doing
destructive things in a situation where that might be unexpected.

So I'm not sure we should do anything at all here.

bug#61652: 28.2; Read-only mode and View mode

[Eli Zaretskii]

> From: Stefan Kangas <stefankangas@gmail.com>
> Date: Tue, 5 Sep 2023 16:48:02 -0700
> Cc: Bernd Rellermeyer <bernd.rellermeyer@t-online.de>, 61652@debbugs.gnu.org
> 
> Eli Zaretskii <eliz@gnu.org> writes:
> 
> >> From: Bernd Rellermeyer <bernd.rellermeyer@t-online.de>
> >> Date: Tue, 21 Feb 2023 13:46:50 +0100
> >> Cc: 61652@debbugs.gnu.org
> >>
> >> In step 3, View mode is entered implicitly, because `view-read-only` is
> >> non-nil. From the user perspective it is only one command. I.e. the user just
> >> turns off and on Read-only mode. That means the user enters View mode vie
> >> Read-Only mode from a writable buffer. I think this should not alter the
> >> behavior of `View-exit` and after calling `View-exit` he should be in a
> >> writable buffer. Or am I wrong?
> >
> > I'm not sure I agree with your interpretation.
> >
> > Does anyone else have an opinion?
> 
> I don't think I agree either.  Once the user starts changing
> read-only-mode, I think disabling it when leaving view-mode would be
> surprising.
> 
> In any case, leaving it as read-only is only a minor annoyance.
> Changing it to read-write means the user can suddenly start doing
> destructive things in a situation where that might be unexpected.
> 
> So I'm not sure we should do anything at all here.

Since no one has chimed in during all this time, I think we should
leave this alone.

bug#61652: 28.2; Read-only mode and View mode

[Stefan Kangas]

tags 61652 wontfix notabug
close 61652
thanks

Eli Zaretskii <eliz@gnu.org> writes:

> Since no one has chimed in during all this time, I think we should
> leave this alone.

Agreed, closing.