From 183e55e2d8a6203d14cefbe6b55ee4bc66628525 Mon Sep 17 00:00:00 2001
From: Mark Wooding <mdw@distorted.org.uk>
Date: Sun, 1 May 2022 13:37:54 +0100
Subject: [PATCH] dot/emacs, el/dot-emacs.el: Add new command for switching
 window configs.

Not sure if I'll like this new approach to working, but it seems OK so
far.
---
 dot/emacs       |  1 +
 el/dot-emacs.el | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/dot/emacs b/dot/emacs
index d661617..3967646 100644
--- a/dot/emacs
+++ b/dot/emacs
@@ -774,6 +774,7 @@
   (global-set-key [?\C-c ?w ?k] 'windmove-up)
   (global-set-key [?\C-c ?w ?l] 'windmove-right)
   (global-set-key [?\C-c ?w ?r] 'winner-redo)
+  (global-set-key [?\C-c ?w ?s] 'mdw-switch-window-configuration)
   (global-set-key [?\C-c ?w ?u] 'winner-undo)
   (global-set-key [?\C-c ?w ?w] 'mdw-set-frame-width)
   (global-set-key [?\C-c ?w up] 'windmove-up)
diff --git a/el/dot-emacs.el b/el/dot-emacs.el
index bc512b4..8b4f8f8 100644
--- a/el/dot-emacs.el
+++ b/el/dot-emacs.el
@@ -287,6 +287,59 @@ This is sadly necessary because Emacs 26 is broken in this regard."
   (set-frame-parameter frame 'background-color (car colour))
   (set-frame-parameter frame 'foreground-color (cdr colour)))
 
+;; Window configuration switching.
+
+(defvar mdw-current-window-configuration nil
+  "The current window configuration register name, or `nil'.")
+
+(defun mdw-switch-window-configuration (register &optional no-save)
+  "Switch make REGISTER be the new current window configuration.
+If a current window configuration register is established, and
+NO-SAVE is nil, then save the current window configuration to
+that register first.
+
+Signal an error if the new register contains something other than
+a window configuration.  If the register is unset then save the
+current window configuration to it immediately.
+
+With one or three C-u, or an odd numeric prefix argument, set
+NO-SAVE, so the previous window configuration register is left
+unchanged.
+
+With two or three C-u, or a prefix argument which is an odd
+multiple of 2, just clear the record of the current window
+configuration register, so that the next switch doesn't save the
+prevailing configuration."
+  (interactive
+   (let ((arg current-prefix-arg))
+     (list (if (or (and (consp arg) (= (car arg) 16) (= (car arg) 64))
+		   (and (integerp arg) (not (zerop (logand arg 2)))))
+	       nil
+	     (register-read-with-preview "Switch to window configuration: "))
+	   (or (and (consp arg) (= (car arg) 4) (= (car arg) 64))
+	       (and (integerp arg) (not (zerop (logand arg 1))))))))
+
+  (let ((current-windows (list (current-window-configuration)
+			       (point-marker)))
+	(register-value (and register (get-register register))))
+    (when (and mdw-current-window-configuration (not no-save))
+      (set-register mdw-current-window-configuration current-windows))
+    (cond ((null register)
+	   (setq mdw-current-window-configuration nil))
+	  ((not (or (null register-value)
+		    (and (consp register-value)
+			 (window-configuration-p (car register-value))
+			 (integer-or-marker-p (cadr register-value))
+			 (null (caddr register-value)))))
+	   (error "Register `%c' is not a window configuration" register))
+	  (t
+	   (cond ((null register-value)
+		  (set-register register current-windows))
+		 (t
+		  (set-window-configuration (car register-value))
+		  (goto-char (cadr register-value))))
+	   (setq mdw-current-window-configuration register)))))
+
 ;; Don't raise windows unless I say so.
 
 (defcustom mdw-inhibit-raise-frame nil
-- 
2.11.0