GNU bug report logs - #18175
files.el: use mapc in (mapcar 'switch-to-buffer ...)

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From: help-debbugs <at> gnu.org (GNU bug Tracking System)
To: Ivan Shmakov <ivan <at> siamics.net>
Cc: tracker <at> debbugs.gnu.org
Subject: bug#18175: closed (files.el: use mapc in (mapcar 'switch-to-buffer
 ...) )
Date: Fri, 23 Jan 2015 15:28:02 +0000

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Your message dated Fri, 23 Jan 2015 15:27:19 +0000
with message-id <87a919o6ug.fsf <at> violet.siamics.net>
and subject line Re: bug#18175: files.el: use mapc in (mapcar 'switch-to-buffer ...)
has caused the debbugs.gnu.org bug report #18175,
regarding files.el: use mapc in (mapcar 'switch-to-buffer ...) 
to be marked as done.

(If you believe you have received this mail in error, please contact
help-debbugs <at> gnu.org.)


-- 
18175: http://debbugs.gnu.org/cgi/bugreport.cgi?bug=18175
GNU Bug Tracking System
Contact help-debbugs <at> gnu.org with problems

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From: Ivan Shmakov <ivan <at> siamics.net>
To: submit <at> debbugs.gnu.org
Subject: files.el: use mapc in (mapcar 'switch-to-buffer ...) 
Date: Sat, 02 Aug 2014 21:55:39 +0000

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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

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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)

[Message part 5 (message/rfc822, inline)]

From: Ivan Shmakov <ivan <at> siamics.net>
To: 18175-done <at> debbugs.gnu.org
Subject: Re: bug#18175: files.el: use mapc in (mapcar 'switch-to-buffer ...)
Date: Fri, 23 Jan 2015 15:27:19 +0000

Version: 25.1

>>>>> Stefan Monnier <monnier <at> iro.umontreal.ca> writes:

[…]

 >> However, I believe that the last two hunks of the one another
 >> variant of the diff (MIMEd) actually make the intent to return the
 >> reverse of the list returned by find-file-noselect /clearer,/ –
 >> although at the expense of adding one extra LoC in each case.

 > Agreed, and neither relies on the return value of `mapc', so those
 > two hunks are indeed good.  Please install them.

	Done; closing.

commit 3e824b05af3a75768a61001fad68e2340af810eb
CommitDate: 2015-01-17 19:33:08 +0000

    Avoid mapcar in two cases in files.el.
    
    * lisp/files.el (find-file-other-window, find-file-other-frame):
    Use mapc instead of mapcar.
    
    Fixes: debbugs:18175

-- 
FSF associate member #7257  np. Chemical Wedding – Bruce Dickinson  230E 334A

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