Do not use switch-to-buffer for working in a temp buffer

* lisp/play/dunnet.el (dunnet): Use pop-to-buffer-same-window instead,
cf. Bug#22244.
(dun-load-d, dun-eval, dun-save-game, dun-do-logfile): Use
with-temp-buffer instead.

1 files changed, 83 insertions, 106 deletions

diff --git a/lisp/play/dunnet.el b/lisp/play/dunnet.el
index e7f45659e9b..d13c967dad5 100644
--- a/lisp/play/dunnet.el
+++ b/lisp/play/dunnet.el
@@ -1176,7 +1176,7 @@ treasures for points?" "4" "four")
 (defun dunnet ()
   "Switch to *dungeon* buffer and start game."
   (interactive)
-  (switch-to-buffer "*dungeon*")
+  (pop-to-buffer-same-window "*dungeon*")
   (dun-mode)
   (setq dun-dead nil)
   (setq dun-room 0)
@@ -2343,20 +2343,16 @@ for a moment, then straighten yourself up.
 ;;; Load an encrypted file, and eval it.
 
 (defun dun-load-d (filename)
-  (let ((old-buffer (current-buffer))
-        (result t))
-    (switch-to-buffer (get-buffer-create "*loadc*"))
-    (erase-buffer)
-    (condition-case nil
-        (insert-file-contents filename)
-      (error (setq result nil)))
-    (when result
+  (let ((result t))
+    (with-temp-buffer
       (condition-case nil
-          (dun-rot13)
-        (error (yank)))
-      (eval-buffer)
-      (kill-buffer (current-buffer)))
-      (switch-to-buffer old-buffer)
+          (insert-file-contents filename)
+        (error (setq result nil)))
+      (when result
+        (condition-case nil
+            (dun-rot13)
+          (error (yank)))
+        (eval-buffer)))
     result))
 
 ;;; Functions to remove an object either from a room, or from inventory.
@@ -2466,23 +2462,11 @@ for a moment, then straighten yourself up.
         (dun-eval varname value)))))
 
 (defun dun-eval (varname value)
-  (let (eval-error)
-    (switch-to-buffer (get-buffer-create "*dungeon-eval*"))
-    (erase-buffer)
-    (insert "(setq ")
-    (insert varname)
-    (insert " ")
-    (insert value)
-    (insert ")")
-    (setq eval-error nil)
+  (with-temp-buffer
+    (insert "(setq " varname " " value ")")
     (condition-case nil
-        (eval-buffer)
-      (error (setq eval-error t)))
-    (kill-buffer (current-buffer))
-    (switch-to-buffer "*dungeon*")
-    (if eval-error
-        (dun-mprincl "Invalid syntax."))))
-
+        (eval-buffer)
+      (error (dun-mprincl "Invalid syntax.")))))
 
 (defun dun-unix-interface ()
   (dun-login)
@@ -3012,49 +2996,43 @@ File not found")))
 (defun dun-save-game (filename)
   (if (not (setq filename (car filename)))
       (dun-mprincl "You must supply a filename for the save.")
-    (if (file-exists-p filename)
-        (delete-file filename))
+    (when (file-exists-p filename) (delete-file filename))
     (setq dun-numsaves (1+ dun-numsaves))
-    (dun-make-save-buffer)
-    (dun-save-val "dun-current-room")
-    (dun-save-val "dun-computer")
-    (dun-save-val "dun-combination")
-    (dun-save-val "dun-visited")
-    (dun-save-val "dun-diggables")
-    (dun-save-val "dun-key-level")
-    (dun-save-val "dun-floppy")
-    (dun-save-val "dun-numsaves")
-    (dun-save-val "dun-numcmds")
-    (dun-save-val "dun-logged-in")
-    (dun-save-val "dungeon-mode")
-    (dun-save-val "dun-jar")
-    (dun-save-val "dun-lastdir")
-    (dun-save-val "dun-black")
-    (dun-save-val "dun-nomail")
-    (dun-save-val "dun-unix-verbs")
-    (dun-save-val "dun-hole")
-    (dun-save-val "dun-uncompressed")
-    (dun-save-val "dun-ethernet")
-    (dun-save-val "dun-sauna-level")
-    (dun-save-val "dun-room-objects")
-    (dun-save-val "dun-room-silents")
-    (dun-save-val "dun-inventory")
-    (dun-save-val "dun-endgame-questions")
-    (dun-save-val "dun-endgame")
-    (dun-save-val "dun-cdroom")
-    (dun-save-val "dun-cdpath")
-    (dun-save-val "dun-correct-answer")
-    (dun-save-val "dun-inbus")
-    (if (dun-compile-save-out filename)
-        (dun-mprincl "Error saving to file.")
-      (dun-do-logfile 'save nil)
-      (switch-to-buffer "*dungeon*")
-      (princ "")
-      (dun-mprincl "Done."))))
-
-(defun dun-make-save-buffer ()
-  (switch-to-buffer (get-buffer-create "*save-dungeon*"))
-  (erase-buffer))
+    (with-temp-buffer
+      (dun-save-val "dun-current-room")
+      (dun-save-val "dun-computer")
+      (dun-save-val "dun-combination")
+      (dun-save-val "dun-visited")
+      (dun-save-val "dun-diggables")
+      (dun-save-val "dun-key-level")
+      (dun-save-val "dun-floppy")
+      (dun-save-val "dun-numsaves")
+      (dun-save-val "dun-numcmds")
+      (dun-save-val "dun-logged-in")
+      (dun-save-val "dungeon-mode")
+      (dun-save-val "dun-jar")
+      (dun-save-val "dun-lastdir")
+      (dun-save-val "dun-black")
+      (dun-save-val "dun-nomail")
+      (dun-save-val "dun-unix-verbs")
+      (dun-save-val "dun-hole")
+      (dun-save-val "dun-uncompressed")
+      (dun-save-val "dun-ethernet")
+      (dun-save-val "dun-sauna-level")
+      (dun-save-val "dun-room-objects")
+      (dun-save-val "dun-room-silents")
+      (dun-save-val "dun-inventory")
+      (dun-save-val "dun-endgame-questions")
+      (dun-save-val "dun-endgame")
+      (dun-save-val "dun-cdroom")
+      (dun-save-val "dun-cdpath")
+      (dun-save-val "dun-correct-answer")
+      (dun-save-val "dun-inbus")
+      (if (dun-compile-save-out filename)
+          (dun-mprincl "Error saving to file.")
+        (dun-do-logfile 'save nil)))
+    (princ "")
+    (dun-mprincl "Done.")))
 
 (defun dun-compile-save-out (filename)
   (let (ferror)
@@ -3100,40 +3078,39 @@ File not found")))
 
 (defun dun-do-logfile (type how)
   (let (ferror)
-    (setq ferror nil)
-    (switch-to-buffer (get-buffer-create "*score*"))
-    (erase-buffer)
-    (condition-case nil
-        (insert-file-contents dun-log-file)
-      (error (setq ferror t)))
-    (unless ferror
-            (goto-char (point-max))
-            (dun-minsert (current-time-string))
-            (dun-minsert " ")
-            (dun-minsert (user-login-name))
-            (dun-minsert " ")
-            (if (eq type 'save)
-                (dun-minsert "saved ")
-              (if (= (dun-endgame-score) 110)
-                  (dun-minsert "won ")
-                (if (not how)
-                    (dun-minsert "quit ")
-                  (dun-minsert "killed by ")
-                  (dun-minsert how)
-                  (dun-minsert " "))))
-            (dun-minsert "at ")
-            (dun-minsert (cadr (nth (abs dun-room) dun-rooms)))
-            (dun-minsert ". score: ")
-            (if (> (dun-endgame-score) 0)
-                (dun-minsert (+ 90 (dun-endgame-score)))
-              (dun-minsert (dun-reg-score)))
-            (dun-minsert " saves: ")
-            (dun-minsert dun-numsaves)
-            (dun-minsert " commands: ")
-            (dun-minsert dun-numcmds)
-            (dun-minsert "\n")
-            (write-region 1 (point-max) dun-log-file nil 1))
-    (kill-buffer (current-buffer))))
+    (with-temp-buffer
+      (condition-case err
+          (insert-file-contents dun-log-file)
+        (error
+         (setq ferror t)
+         (dun-mprincl (error-message-string err))))
+      (when (null ferror)
+        (goto-char (point-max))
+        (dun-minsert (current-time-string))
+        (dun-minsert " ")
+        (dun-minsert (user-login-name))
+        (dun-minsert " ")
+        (if (eq type 'save)
+            (dun-minsert "saved ")
+          (if (= (dun-endgame-score) 110)
+              (dun-minsert "won ")
+            (if (not how)
+                (dun-minsert "quit ")
+              (dun-minsert "killed by ")
+              (dun-minsert how)
+              (dun-minsert " "))))
+        (dun-minsert "at ")
+        (dun-minsert (cadr (nth (abs dun-room) dun-rooms)))
+        (dun-minsert ". score: ")
+        (if (> (dun-endgame-score) 0)
+            (dun-minsert (+ 90 (dun-endgame-score)))
+          (dun-minsert (dun-reg-score)))
+        (dun-minsert " saves: ")
+        (dun-minsert dun-numsaves)
+        (dun-minsert " commands: ")
+        (dun-minsert dun-numcmds)
+        (dun-minsert "\n")
+        (write-region 1 (point-max) dun-log-file nil 1)))))
 
 
 ;;;;