Subject: files.el: use mapc in (mapcar 'switch-to-buffer ...)

From: Ivan Shmakov <[email-masked]>
Date: Sat, 02 Aug 2014 21:55:39 +0000

Package:  emacs
Severity: wishlist

	Given that switch-to-buffer returns its argument, /and/ given
	that mapc returns the sequence it’s given, I suggest that the
	(mapcar 'switch-to-buffer LIST) forms in lisp/files.el be
	replaced with (mapc 'switch-to-buffer LIST), – if only to avoid
	the unnecessary consing when the list is effectively copied in
	the mapcar case.

	The lists mapcar is applied to in such cases are returned from
	find-file-noselect, and so, as it seems, are “fresh” ones
	anyway.

	A possible patch is MIMEd.

-- 
FSF associate member #7257  http://boycottsystemd.org/  … 3013 B6A0 230E 334A
diff --git a/lisp/files.el b/lisp/files.el
index 9272e98..e604ce7 100644
--- a/lisp/files.el
+++ b/lisp/files.el
@@ -1428,7 +1428,7 @@ automatically choosing a major mode, use \\[find-file-literally]."
                         (confirm-nonexistent-file-or-buffer)))
   (let ((value (find-file-noselect filename nil nil wildcards)))
     (if (listp value)
-	(mapcar 'switch-to-buffer (nreverse value))
+	(mapc 'switch-to-buffer (nreverse value))
       (switch-to-buffer value))))
 
 (defun find-file-other-window (filename &optional wildcards)
@@ -1451,7 +1451,7 @@ expand wildcards (if any) and visit multiple files."
 	(progn
 	  (setq value (nreverse value))
 	  (cons (switch-to-buffer-other-window (car value))
-		(mapcar 'switch-to-buffer (cdr value))))
+		(mapc 'switch-to-buffer (cdr value))))
       (switch-to-buffer-other-window value))))
 
 (defun find-file-other-frame (filename &optional wildcards)
@@ -1474,7 +1474,7 @@ expand wildcards (if any) and visit multiple files."
 	(progn
 	  (setq value (nreverse value))
 	  (cons (switch-to-buffer-other-frame (car value))
-		(mapcar 'switch-to-buffer (cdr value))))
+		(mapc 'switch-to-buffer (cdr value))))
       (switch-to-buffer-other-frame value))))
 
 (defun find-file-existing (filename)