basic: stop creating a scratch buffer when not demanded

* basic.el (durand-read-buffer-to-switch, #'read-buffer-to-switch):
  The default behaviour of read-buffer-to-switch creates a scratch
  buffer, if there is no other good buffer to switch to.  But this is
  not what I demand, and is oft a surprise to me.  If there is no
  other buffer to switch to, just present me with the current buffer.
  The modified version does just this.

1 files changed, 37 insertions, 0 deletions

diff --git a/basic.el b/basic.el
index b2ab6d0..aa087f1 100644
--- a/basic.el
+++ b/basic.el
@@ -527,6 +527,43 @@ Don't ask me to confirm my choice. --- Durand"
 
 (define-key global-map (vector ?\s-Z) #'undo-only)
 
+;;; Don't create a scratch buffer
+
+(defun durand-read-buffer-to-switch (prompt)
+  "Read the name of a buffer to switch to, prompting with PROMPT.
+Return the name of the buffer as a string.
+
+This function is intended for the `switch-to-buffer' family of
+commands since these need to omit the name of the current buffer
+from the list of completions and default values.
+
+Modified to stop creating a buffer, when there is only one buffer
+left.  --- 2022-11-17 22:56:20.746698"
+  (let ((rbts-completion-table (internal-complete-buffer-except))
+        (default-buffer (other-buffer (current-buffer))))
+    (cond
+     ((string= (buffer-name default-buffer) "*scratch*")
+      (kill-buffer default-buffer)
+      (setq default-buffer (current-buffer))))
+    (minibuffer-with-setup-hook
+        (lambda ()
+          (setq minibuffer-completion-table rbts-completion-table)
+          ;; Since rbts-completion-table is built dynamically, we
+          ;; can't just add it to the default value of
+          ;; icomplete-with-completion-tables, so we add it
+          ;; here manually.
+          (if (and (boundp 'icomplete-with-completion-tables)
+                   (listp icomplete-with-completion-tables))
+              (setq-local icomplete-with-completion-tables
+                          (cons rbts-completion-table
+                                icomplete-with-completion-tables))))
+      (read-buffer
+       prompt default-buffer
+       (confirm-nonexistent-file-or-buffer)))))
+
+(advice-add #'read-buffer-to-switch :override
+            #'durand-read-buffer-to-switch)
+
 ;;; Save close
 
 ;;;###autoload