GNU bug report logs - #13251
Wishlist: Add ability to set initial buffer for new frames.

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Constantin Kulikov <zxnotdead <at> gmail.com>
To: bug-gnu-emacs <at> gnu.org
Subject: Wishlist: Add ability to set initial buffer for new frames.
Date: Sat, 22 Dec 2012 00:16:58 +0300

[Message part 1 (text/plain, inline)]

// Discussion in devel.
https://lists.gnu.org/archive/html/emacs-devel/2012-12/msg00521.html
Short:
I want to be able to set buffer that will be displayed in window of newly
created frame.
I need it for my emacs package, that will save and restore some emacs state
including
last window configurations, opened and displayed buffers and such.
I tried this: add hook to `after-make-frame-functions'. Inside this hook I
do
`(switch-to-buffer <some-buffer>)' and frame is switched to that
<some-buffer> at first,
but after a short time it's switched to *scratch*.

The one way I found how to overcome this behaviour is by setting the
`initial-buffer-choice' in the `after-make-frame-functions' hook. One
drawback of this
approach is that it could only be set to name of file, t or nil and so
there is no way to
force switching to buffer without underlying file. This could be fixed int
server.el:1258
replacing

  (unless (or files commands)
        (if (stringp initial-buffer-choice)
        (find-file initial-buffer-choice)
          (switch-to-buffer (get-buffer-create "*scratch*")
                'norecord)))

to
          (unless (or files commands)
            (switch-to-buffer
             (get-buffer-create
              (or (cond
                   ((stringp initial-buffer-choice) (find-file-noselect
initial-buffer-choice))
                   ((functionp initial-buffer-choice) (funcall
initial-buffer-choice)))
                  "*scratch*"))
             'norecord))

and modified defcustom in in startup.el:41 would be:

(defcustom initial-buffer-choice nil
  "Buffer to show after starting Emacs.
If the value is nil and `inhibit-startup-screen' is nil, show the
startup screen.  If the value is a string, visit the specified file
or directory using `find-file'.  If t, open the `*scratch*'
buffer. If function, switch to a buffer returned by this function.

A string value also causes emacsclient to open the specified file
or directory when no target file is specified."
  :type '(choice
      (const     :tag "Startup screen" nil)
      (directory :tag "Directory" :value "~/")
      (file      :tag "File" :value "~/.emacs")
      (function  :tag "Function")
      (const     :tag "Lisp scratch buffer" t))
  :version "23.1"
  :group 'initialization)

This code allows setting `initial-buffer-choice' to a function returning
needed buffer.

[Message part 2 (text/html, inline)]

Message #8 received at 13251 <at> debbugs.gnu.org (full text, mbox):

From: Constantin Kulikov <zxnotdead <at> gmail.com>
To: 13251 <at> debbugs.gnu.org
Subject: Re: Wishlist: Add ability to set initial buffer for new frames.
Date: Sat, 22 Dec 2012 00:30:03 +0300

[Message part 1 (text/plain, inline)]

ah sorry, don't need that `or' in server.el:
          (unless (or files commands)
            (switch-to-buffer
             (get-buffer-create
              (cond
               ((stringp initial-buffer-choice) (find-file-noselect
initial-buffer-choice))
               ((functionp initial-buffer-choice) (funcall
initial-buffer-choice))
               (t "*scratch*")))
             'norecord))



2012/12/22 Constantin Kulikov <zxnotdead <at> gmail.com>

> // Discussion in devel.
> https://lists.gnu.org/archive/html/emacs-devel/2012-12/msg00521.html
> Short:
> I want to be able to set buffer that will be displayed in window of newly
> created frame.
> I need it for my emacs package, that will save and restore some emacs
> state including
> last window configurations, opened and displayed buffers and such.
> I tried this: add hook to `after-make-frame-functions'. Inside this hook I
> do
> `(switch-to-buffer <some-buffer>)' and frame is switched to that
> <some-buffer> at first,
> but after a short time it's switched to *scratch*.
>
> The one way I found how to overcome this behaviour is by setting the
> `initial-buffer-choice' in the `after-make-frame-functions' hook. One
> drawback of this
> approach is that it could only be set to name of file, t or nil and so
> there is no way to
> force switching to buffer without underlying file. This could be fixed int
> server.el:1258
> replacing
>
>   (unless (or files commands)
>         (if (stringp initial-buffer-choice)
>         (find-file initial-buffer-choice)
>           (switch-to-buffer (get-buffer-create "*scratch*")
>                 'norecord)))
>
> to
>           (unless (or files commands)
>             (switch-to-buffer
>              (get-buffer-create
>               (or (cond
>                    ((stringp initial-buffer-choice) (find-file-noselect
> initial-buffer-choice))
>                    ((functionp initial-buffer-choice) (funcall
> initial-buffer-choice)))
>                   "*scratch*"))
>              'norecord))
>
> and modified defcustom in in startup.el:41 would be:
>
> (defcustom initial-buffer-choice nil
>   "Buffer to show after starting Emacs.
> If the value is nil and `inhibit-startup-screen' is nil, show the
> startup screen.  If the value is a string, visit the specified file
> or directory using `find-file'.  If t, open the `*scratch*'
> buffer. If function, switch to a buffer returned by this function.
>
> A string value also causes emacsclient to open the specified file
> or directory when no target file is specified."
>   :type '(choice
>       (const     :tag "Startup screen" nil)
>       (directory :tag "Directory" :value "~/")
>       (file      :tag "File" :value "~/.emacs")
>       (function  :tag "Function")
>       (const     :tag "Lisp scratch buffer" t))
>   :version "23.1"
>   :group 'initialization)
>
> This code allows setting `initial-buffer-choice' to a function returning
> needed buffer.
>
>

[Message part 2 (text/html, inline)]

Message #11 received at 13251 <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Constantin Kulikov <zxnotdead <at> gmail.com>
Cc: 13251 <at> debbugs.gnu.org
Subject: Re: bug#13251: Wishlist: Add ability to set initial buffer for new
	frames.
Date: Sat, 22 Dec 2012 16:42:21 +0100

> (defcustom initial-buffer-choice nil
>   "Buffer to show after starting Emacs.
> If the value is nil and `inhibit-startup-screen' is nil, show the
> startup screen.  If the value is a string, visit the specified file
> or directory using `find-file'.  If t, open the `*scratch*'
> buffer. If function, switch to a buffer returned by this function.

As for the last sentence I'd prefer "If it is a function, switch to the
buffer returned by that function."

> A string value also causes emacsclient to open the specified file
> or directory when no target file is specified."
>   :type '(choice
>       (const     :tag "Startup screen" nil)
>       (directory :tag "Directory" :value "~/")
>       (file      :tag "File" :value "~/.emacs")
>       (function  :tag "Function")
>       (const     :tag "Lisp scratch buffer" t))
>   :version "23.1"

Too late for "23.1" use "24.4" instead.

>   :group 'initialization)
>
> This code allows setting `initial-buffer-choice' to a function returning
> needed buffer.

Could you please send us a patch based on these remarks (including the
change you sketched in your second mail)?

Thanks, martin

Message #14 received at 13251 <at> debbugs.gnu.org (full text, mbox):

From: Constantin Kulikov <zxnotdead <at> gmail.com>
To: martin rudalics <rudalics <at> gmx.at>
Cc: 13251 <at> debbugs.gnu.org
Subject: Re: bug#13251: Wishlist: Add ability to set initial buffer for new
	frames.
Date: Sat, 22 Dec 2012 22:51:25 +0300

[Message part 1 (text/plain, inline)]

Thanks for the tips.



2012/12/22 martin rudalics <rudalics <at> gmx.at>

> > (defcustom initial-buffer-choice nil
> >   "Buffer to show after starting Emacs.
> > If the value is nil and `inhibit-startup-screen' is nil, show the
> > startup screen.  If the value is a string, visit the specified file
> > or directory using `find-file'.  If t, open the `*scratch*'
> > buffer. If function, switch to a buffer returned by this function.
>
> As for the last sentence I'd prefer "If it is a function, switch to the
> buffer returned by that function."
>
> > A string value also causes emacsclient to open the specified file
> > or directory when no target file is specified."
> >   :type '(choice
> >       (const     :tag "Startup screen" nil)
> >       (directory :tag "Directory" :value "~/")
> >       (file      :tag "File" :value "~/.emacs")
> >       (function  :tag "Function")
> >       (const     :tag "Lisp scratch buffer" t))
> >   :version "23.1"
>
> Too late for "23.1" use "24.4" instead.
>
> >   :group 'initialization)
> >
> > This code allows setting `initial-buffer-choice' to a function returning
> > needed buffer.
>
> Could you please send us a patch based on these remarks (including the
> change you sketched in your second mail)?
>
> Thanks, martin
>

[Message part 2 (text/html, inline)]

[initial-buffer-choice-as-function.patch (application/octet-stream, attachment)]

Message #17 received at 13251 <at> debbugs.gnu.org (full text, mbox):

From: Constantin Kulikov <zxnotdead <at> gmail.com>
To: martin rudalics <rudalics <at> gmx.at>
Cc: 13251 <at> debbugs.gnu.org
Subject: Re: bug#13251: Wishlist: Add ability to set initial buffer for new
	frames.
Date: Sat, 22 Dec 2012 23:18:28 +0300

[Message part 1 (text/plain, inline)]

argh. :( Sorry made a small typo in patch attached in previous message.



2012/12/22 Constantin Kulikov <zxnotdead <at> gmail.com>

> Thanks for the tips.
>
>
>
> 2012/12/22 martin rudalics <rudalics <at> gmx.at>
>
>> > (defcustom initial-buffer-choice nil
>> >   "Buffer to show after starting Emacs.
>> > If the value is nil and `inhibit-startup-screen' is nil, show the
>> > startup screen.  If the value is a string, visit the specified file
>> > or directory using `find-file'.  If t, open the `*scratch*'
>> > buffer. If function, switch to a buffer returned by this function.
>>
>> As for the last sentence I'd prefer "If it is a function, switch to the
>> buffer returned by that function."
>>
>> > A string value also causes emacsclient to open the specified file
>> > or directory when no target file is specified."
>> >   :type '(choice
>> >       (const     :tag "Startup screen" nil)
>> >       (directory :tag "Directory" :value "~/")
>> >       (file      :tag "File" :value "~/.emacs")
>> >       (function  :tag "Function")
>> >       (const     :tag "Lisp scratch buffer" t))
>> >   :version "23.1"
>>
>> Too late for "23.1" use "24.4" instead.
>>
>> >   :group 'initialization)
>> >
>> > This code allows setting `initial-buffer-choice' to a function returning
>> > needed buffer.
>>
>> Could you please send us a patch based on these remarks (including the
>> change you sketched in your second mail)?
>>
>> Thanks, martin
>>
>
>

[Message part 2 (text/html, inline)]

[initial-buffer-choice-as-function.patch (application/octet-stream, attachment)]

Message #20 received at 13251 <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Constantin Kulikov <zxnotdead <at> gmail.com>
Cc: 13251 <at> debbugs.gnu.org
Subject: Re: bug#13251: Wishlist: Add ability to set initial buffer for new
	frames.
Date: Sun, 23 Dec 2012 11:14:10 +0100

> Thanks for the tips.

Thanks for the patch.  Unfortunately, we are not yet done :-(

> === modified file 'lisp/server.el'
> --- lisp/server.el	2012-11-09 06:28:27 +0000
> +++ lisp/server.el	2012-12-22 19:36:57 +0000
> @@ -1256,12 +1256,18 @@
>            (mapc 'funcall (nreverse commands))
>
>  	  ;; If we were told only to open a new client, obey
> -	  ;; `initial-buffer-choice' if it specifies a file.
> -	  (unless (or files commands)
> -	    (if (stringp initial-buffer-choice)
> -		(find-file initial-buffer-choice)
> -	      (switch-to-buffer (get-buffer-create "*scratch*")
> -				'norecord)))
> +	  ;; `initial-buffer-choice' if it specifies a file
> +          ;; or a function
> +          (unless (or files commands)

Here we have to make sure that we do _not_ switch to *scratch* when
`initial-buffer-choice' is nil but show the initial start screen.

> +            (switch-to-buffer
> +             (get-buffer-create
> +              (cond
> +               ((stringp initial-buffer-choice)
> +                (find-file-noselect initial-buffer-choice))
> +               ((functionp initial-buffer-choice)
> +                (funcall initial-buffer-choice))

Let's make sure that both `find-file-noselect' and the function called
via `initial-buffer-choice' really returned a live buffer.  So please
add a call to `buffer-live-p' for these cases.  Which also means that
Stefan's initial proposal for a let-bound `buf' is the better choice ;-)
(he's usually always right in these things).

> +               (t "*scratch*")))
> +             'norecord))
>
>            ;; Delete the client if necessary.
>            (cond
>
> === modified file 'lisp/startup.el'
> --- lisp/startup.el	2012-12-01 02:08:30 +0000
> +++ lisp/startup.el	2012-12-22 20:09:27 +0000
> @@ -43,7 +43,7 @@
>  If the value is nil and `inhibit-startup-screen' is nil, show the
>  startup screen.  If the value is a string, visit the specified file
>  or directory using `find-file'.

I suppose this is no longer true.  Let's say "switch to a buffer
visiting the file or directory specified by the string" instead.

>   If t, open the `*scratch*'
> -buffer.

This should come after the function item.  Note that we are not overly
precise in the doc-string - any non-nil value of `initial-buffer-choice'
will show *scratch*.  But it's better to not tell that in the doc-string
so we have room for future changes - just like the one you proposed.

> +buffer. If function, switch to a buffer returned by this function.

"If the value is a function, switch to the buffer returned by that
function." seems more precise here.

>  A string value also causes emacsclient to open the specified file
>  or directory when no target file is specified."
> @@ -51,8 +51,9 @@
>  	  (const     :tag "Startup screen" nil)
>  	  (directory :tag "Directory" :value "~/")
>  	  (file      :tag "File" :value "~/.emacs")
> +          (function  :tag "Function")
>  	  (const     :tag "Lisp scratch buffer" t))
> -  :version "23.1"
> +  :version "24.4"
>    :group 'initialization)
>
>  (defcustom inhibit-startup-screen nil

And now comes the last problem.  The function `command-line-1' (in
startup.el) contains these lines:

    (when (eq initial-buffer-choice t)
      ;; When initial-buffer-choice equals t make sure that *scratch*
      ;; exists.
      (get-buffer-create "*scratch*"))

I'd remove them because we can handle them here:

    (when initial-buffer-choice
      (cond ((eq initial-buffer-choice t)
	     (switch-to-buffer (get-buffer-create "*scratch*")))
	    ((stringp initial-buffer-choice)
	     (find-file initial-buffer-choice))))

If we allow `initial-buffer-choice' to specify a function, we have to
handle it here in the same way as in server.el.

martin

Message #23 received at 13251 <at> debbugs.gnu.org (full text, mbox):

From: Constantin Kulikov <zxnotdead <at> gmail.com>
To: 13251 <at> debbugs.gnu.org
Subject: Fwd: bug#13251: Wishlist: Add ability to set initial buffer for new
	frames.
Date: Sun, 23 Dec 2012 20:04:24 +0300

[Message part 1 (text/plain, inline)]

---------- Forwarded message ----------
From: Constantin Kulikov <zxnotdead <at> gmail.com>
Date: 2012/12/23
Subject: Re: bug#13251: Wishlist: Add ability to set initial buffer for new
frames.
To: martin rudalics <rudalics <at> gmx.at>


another attempt...

[Message part 2 (text/html, inline)]

[initial-buffer-choice-as-function.patch (application/octet-stream, attachment)]

Message #26 received at 13251 <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Constantin Kulikov <zxnotdead <at> gmail.com>
Cc: 13251 <at> debbugs.gnu.org
Subject: Re: bug#13251: Wishlist: Add ability to set initial buffer for new
	frames.
Date: Mon, 24 Dec 2012 19:05:09 +0100

> another attempt...

Committed as a combination of your previous and present patch.  Please
have a look.

Thanks, martin

Message #29 received at 13251 <at> debbugs.gnu.org (full text, mbox):

From: Constantin Kulikov <zxnotdead <at> gmail.com>
To: martin rudalics <rudalics <at> gmx.at>
Cc: 13251 <at> debbugs.gnu.org
Subject: Re: bug#13251: Wishlist: Add ability to set initial buffer for new
	frames.
Date: Mon, 24 Dec 2012 22:37:04 +0300

[Message part 1 (text/plain, inline)]

seems it works as I need. Thanks.


2012/12/24 martin rudalics <rudalics <at> gmx.at>

> > another attempt...
>
> Committed as a combination of your previous and present patch.  Please
> have a look.
>
> Thanks, martin
>

[Message part 2 (text/html, inline)]

Message #34 received at 13251-done <at> debbugs.gnu.org (full text, mbox):

From: martin rudalics <rudalics <at> gmx.at>
To: Constantin Kulikov <zxnotdead <at> gmail.com>
Cc: 13251-done <at> debbugs.gnu.org
Subject: Re: bug#13251: Wishlist: Add ability to set initial buffer for new
	frames.
Date: Wed, 02 Jan 2013 09:03:18 +0100

> seems it works as I need. Thanks.

Bug closed.

Thanks, martin

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