Buffer local `switch-to-buffer-preserve-window-point'

Buffer local `switch-to-buffer-preserve-window-point'

[Evgeny Zajcev]

[-- Attachment #1: Type: text/plain, Size: 1137 bytes --]

I think we should add to the documentation that buffer local values for
`switch-to-buffer-obey-display-actions' and
`switch-to-buffer-preserve-window-point' won't work as user would expect.

The problem with their buffer local values is that they are used for buffer
logic *before* buffer is set as current, see `switch-to-buffer'.  We should
either use `(buffer-local-value NAME buffer)' to get their values in
`switch-to-buffer', or add to the documentation that they should not have
buffer local values.

Here is code snippet to trigger unexpected behaviour:

  ;; Switch to scratch and eval
  (progn
    (setq switch-to-buffer-preserve-window-point t)
    (with-current-buffer (get-buffer-create "pwp")
     (setq-local switch-to-buffer-preserve-window-point nil)
     (insert "asnoteh asoensnaot heusnatoeh usanotehu aeosntuhaoe")
     (point))
    (switch-to-buffer "pwp")
    (switch-to-other-buffer 1)

    (with-current-buffer "pwp"
     (goto-char 10)
     (point))
    (switch-to-buffer "pwp")
    ;; Expecting point to be at 10 position, but it remains at the end
    ;; of the line
    )

What do you think?

Thanks

-- 
lg

[-- Attachment #2: Type: text/html, Size: 1553 bytes --]

Re: Buffer local `switch-to-buffer-preserve-window-point'

[martin rudalics]

 >      (switch-to-other-buffer 1)

Please also provide the code for this function.

Thanks, martin

Re: Buffer local `switch-to-buffer-preserve-window-point'

[Evgeny Zajcev]

[-- Attachment #1: Type: text/plain, Size: 304 bytes --]

пн, 30 нояб. 2020 г. в 12:06, martin rudalics <rudalics@gmx.at>:

>  >      (switch-to-other-buffer 1)
>
> Please also provide the code for this function.
>

Ah, sorry, I thought that is in Emacs, but it was from my init.el :)),
replace with (switch-to-buffer (other-buffer))

-- 
lg

[-- Attachment #2: Type: text/html, Size: 682 bytes --]

Re: Buffer local `switch-to-buffer-preserve-window-point'

[martin rudalics]

 > Ah, sorry, I thought that is in Emacs, but it was from my init.el :)),
 > replace with (switch-to-buffer (other-buffer))

OK.

 > The problem with their buffer local values is that they are used for buffer
 > logic *before* buffer is set as current, see `switch-to-buffer'.  We should
 > either use `(buffer-local-value NAME buffer)' to get their values in
 > `switch-to-buffer',

Good idea.  Could you write a patch?

martin

Re: Buffer local `switch-to-buffer-preserve-window-point'

[Evgeny Zajcev]

[-- Attachment #1.1: Type: text/plain, Size: 723 bytes --]

пн, 30 нояб. 2020 г. в 20:30, martin rudalics <rudalics@gmx.at>:

>  > Ah, sorry, I thought that is in Emacs, but it was from my init.el :)),
>  > replace with (switch-to-buffer (other-buffer))
>
> OK.
>
>  > The problem with their buffer local values is that they are used for
> buffer
>  > logic *before* buffer is set as current, see `switch-to-buffer'.  We
> should
>  > either use `(buffer-local-value NAME buffer)' to get their values in
>  > `switch-to-buffer',
>
> Good idea.  Could you write a patch?
>
>
Sure, here it is

Probably same should be done for `switch-to-buffer-obey-display-actions',
but at the moment I care more about `switch-to-buffer-preserve-window-point'

-- 
lg

[-- Attachment #1.2: Type: text/html, Size: 1193 bytes --]

[-- Attachment #2: 0001-Fix-use-of-switch-to-buffer-preserve-window-point.patch --]
[-- Type: text/x-patch, Size: 1417 bytes --]

From 2e25a05e0b9eb3a891be369bc7428fb017d8902f Mon Sep 17 00:00:00 2001
From: Zajcev Evgeny <zevlg@yandex.ru>
Date: Mon, 30 Nov 2020 20:51:18 +0300
Subject: [PATCH] Fix use of switch-to-buffer-preserve-window-point

* lisp/window.el (switch-to-buffer): Regard buffer local value
for switch-to-buffer-preserve-window-point variable
---
 lisp/window.el | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/lisp/window.el b/lisp/window.el
index 82976bf836..ea3f581a2f 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -8566,13 +8566,13 @@ switch-to-buffer
 
       (when set-window-start-and-point
         (let* ((entry (assq buffer (window-prev-buffers)))
-	       (displayed (and (eq switch-to-buffer-preserve-window-point
-				   'already-displayed)
+               (preserver-win-point
+                (buffer-local-value 'switch-to-buffer-preserve-window-point
+                                    buffer))
+	       (displayed (and (eq preserver-win-point 'already-displayed)
 			       (get-buffer-window buffer 0))))
 	  (set-window-buffer nil buffer)
-	  (when (and entry
-		     (or (eq switch-to-buffer-preserve-window-point t)
-		         displayed))
+	  (when (and entry (or (eq preserver-win-point t) displayed))
 	    ;; Try to restore start and point of buffer in the selected
 	    ;; window (Bug#4041).
 	    (set-window-start (selected-window) (nth 1 entry) t)
-- 
2.25.1

Re: Buffer local `switch-to-buffer-preserve-window-point'

[Evgeny Zajcev]

[-- Attachment #1.1: Type: text/plain, Size: 912 bytes --]

пн, 30 нояб. 2020 г. в 20:54, Evgeny Zajcev <lg.zevlg@gmail.com>:

>
>
> пн, 30 нояб. 2020 г. в 20:30, martin rudalics <rudalics@gmx.at>:
>
>>  > Ah, sorry, I thought that is in Emacs, but it was from my init.el :)),
>>  > replace with (switch-to-buffer (other-buffer))
>>
>> OK.
>>
>>  > The problem with their buffer local values is that they are used for
>> buffer
>>  > logic *before* buffer is set as current, see `switch-to-buffer'.  We
>> should
>>  > either use `(buffer-local-value NAME buffer)' to get their values in
>>  > `switch-to-buffer',
>>
>> Good idea.  Could you write a patch?
>>
>>
> Sure, here it is
>
> Probably same should be done for `switch-to-buffer-obey-display-actions',
> but at the moment I care more about `switch-to-buffer-preserve-window-point'
>

Sorry, there was a typo: preserver instead of preserve, here is the update

-- 
lg

[-- Attachment #1.2: Type: text/html, Size: 1680 bytes --]

[-- Attachment #2: 0001-Fix-use-of-switch-to-buffer-preserve-window-point.patch --]
[-- Type: text/x-patch, Size: 1418 bytes --]

From 2e25a05e0b9eb3a891be369bc7428fb017d8902f Mon Sep 17 00:00:00 2001
From: Zajcev Evgeny <zevlg@yandex.ru>
Date: Mon, 30 Nov 2020 20:51:18 +0300
Subject: [PATCH 1/2] Fix use of switch-to-buffer-preserve-window-point

* lisp/window.el (switch-to-buffer): Regard buffer local value
for switch-to-buffer-preserve-window-point variable
---
 lisp/window.el | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/lisp/window.el b/lisp/window.el
index 82976bf836..ea3f581a2f 100644
--- a/lisp/window.el
+++ b/lisp/window.el
@@ -8566,13 +8566,13 @@ switch-to-buffer
 
       (when set-window-start-and-point
         (let* ((entry (assq buffer (window-prev-buffers)))
-	       (displayed (and (eq switch-to-buffer-preserve-window-point
-				   'already-displayed)
+               (preserve-win-point
+                (buffer-local-value 'switch-to-buffer-preserve-window-point
+                                    buffer))
+	       (displayed (and (eq preserve-win-point 'already-displayed)
 			       (get-buffer-window buffer 0))))
 	  (set-window-buffer nil buffer)
-	  (when (and entry
-		     (or (eq switch-to-buffer-preserve-window-point t)
-		         displayed))
+	  (when (and entry (or (eq preserve-win-point t) displayed))
 	    ;; Try to restore start and point of buffer in the selected
 	    ;; window (Bug#4041).
 	    (set-window-start (selected-window) (nth 1 entry) t)
-- 
2.25.1

Re: Buffer local `switch-to-buffer-preserve-window-point'

[martin rudalics]

 >> Sure, here it is
 >>
 >> Probably same should be done for `switch-to-buffer-obey-display-actions',

Probably.

 >> but at the moment I care more about `switch-to-buffer-preserve-window-point'
 >>
 >
 > Sorry, there was a typo: preserver instead of preserve, here is the update

Thanks.  I suppose you can't install it yourself so I will do so tomorrow
if the state of my machines permits it.

martin

Re: Buffer local `switch-to-buffer-preserve-window-point'

[martin rudalics]

 > Thanks.  I suppose you can't install it yourself so I will do so tomorrow
 > if the state of my machines permits it.

I've got the permission so this is done.

martin