From dc646358274fbfdab6ef3dfb7717bc4a52f607f3 Mon Sep 17 00:00:00 2001
From: Constantin Kulikov <zxnotdead@gmail.com>
Date: Mon, 24 Dec 2012 18:49:19 +0100
Subject: [PATCH] Allow function as value of initial-buffer-choice (Bug#13251).

* startup.el (initial-buffer-choice): Allow function as value
(Bug#13251).
(command-line-1): Handle case where initial-buffer-choice
specifies a function.
* server.el (server-execute): Handle case where
initial-buffer-choice specifies a function.
---
 etc/NEWS        |  3 +++
 lisp/ChangeLog  |  9 +++++++++
 lisp/server.el  | 17 +++++++++++------
 lisp/startup.el | 22 ++++++++++++++--------
 4 files changed, 37 insertions(+), 14 deletions(-)

diff --git a/etc/NEWS b/etc/NEWS
index 6d97e9a5772..3c4a76b188e 100644
--- a/etc/NEWS
+++ b/etc/NEWS
@@ -39,6 +39,9 @@ if there is one.
 This unfinished feature was introduced by accident in Emacs 23.1;
 simply disabling Transient Mark mode does the same thing.
 
+** `initial-buffer-choice' can now specify a function to set up the
+initial buffer.
+
 ** ACL support has been added.
 +++
 *** Emacs preserves the ACL entries of files when backing up.
diff --git a/lisp/ChangeLog b/lisp/ChangeLog
index 1438a230550..2181a6dde7e 100644
--- a/lisp/ChangeLog
+++ b/lisp/ChangeLog
@@ -1,3 +1,12 @@
+2012-12-24  Constantin Kulikov <zxnotdead@gmail.com>  (tiny change)
+
+	* startup.el (initial-buffer-choice): Allow function as value
+	(Bug#13251).
+	(command-line-1): Handle case where initial-buffer-choice
+	specifies a function.
+	* server.el (server-execute): Handle case where
+	initial-buffer-choice specifies a function.
+
 2012-12-24  Lars Ingebrigtsen  <larsi@gnus.org>
 
 	* mail/smtpmail.el (smtpmail-try-auth-method): Refactored out into
diff --git a/lisp/server.el b/lisp/server.el
index c78e3e376aa..59f75722ccb 100644
--- a/lisp/server.el
+++ b/lisp/server.el
@@ -1256,12 +1256,17 @@ The following commands are accepted by the client:
           (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)
+            (let ((buf
+                   (cond ((stringp initial-buffer-choice)
+			  (find-file-noselect initial-buffer-choice))
+			 ((functionp initial-buffer-choice)
+			  (funcall initial-buffer-choice)))))
+	      (switch-to-buffer
+	       (if (buffer-live-p buf) buf (get-buffer-create "*scratch*"))
+	       'norecord)))
 
           ;; Delete the client if necessary.
           (cond
diff --git a/lisp/startup.el b/lisp/startup.el
index ec6d45a294d..6a207bab0bf 100644
--- a/lisp/startup.el
+++ b/lisp/startup.el
@@ -41,9 +41,10 @@
 (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.
+startup screen.  If the value is a string, switch to a buffer
+visiting the file or directory specified by that string.  If the
+value is a function, switch to the buffer returned by that
+function.  If t, open the `*scratch*' buffer.
 
 A string value also causes emacsclient to open the specified file
 or directory when no target file is specified."
@@ -51,8 +52,9 @@ or directory when no target file is specified."
 	  (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
@@ -2323,10 +2325,14 @@ A fancy display is used on graphic displays, normal otherwise."
 	     (set-buffer-modified-p nil))))
 
     (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))))
+      (let ((buf
+             (cond ((stringp initial-buffer-choice)
+		    (find-file-noselect initial-buffer-choice))
+		   ((functionp initial-buffer-choice)
+		    (funcall initial-buffer-choice)))))
+	(switch-to-buffer
+	 (if (buffer-live-p buf) buf (get-buffer-create "*scratch*"))
+	 'norecord)))
 
     (if (or inhibit-startup-screen
 	    initial-buffer-choice
-- 
2.39.5