bug#13251: Wishlist: Add ability to set initial buffer for new frames.

[martin rudalics <rudalics@gmx.at>]

 > 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