From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: pjb@informatimago.com (Pascal J. Bourguignon) Newsgroups: gmane.emacs.help Subject: Re: Setting the nth element of a list Date: Fri, 05 Jun 2009 17:08:59 +0200 Organization: Anevia SAS Message-ID: <7cab4mogz8.fsf@pbourguignon.anevia.com> References: <8a7c4d36-195d-4517-827e-7fbeca7ae03f@r34g2000vba.googlegroups.com> <10cee0d4-43ff-4d2b-9a9b-735c8f83ffd4@x6g2000vbg.googlegroups.com> <7ceityols1.fsf@pbourguignon.informatimago.com> NNTP-Posting-Host: lo.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1244216447 19326 80.91.229.12 (5 Jun 2009 15:40:47 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Fri, 5 Jun 2009 15:40:47 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Fri Jun 05 17:40:43 2009 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([199.232.76.165]) by lo.gmane.org with esmtp (Exim 4.50) id 1MCbX7-000823-3h for geh-help-gnu-emacs@m.gmane.org; Fri, 05 Jun 2009 17:40:41 +0200 Original-Received: from localhost ([127.0.0.1]:56912 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MCbX6-0002u8-Lk for geh-help-gnu-emacs@m.gmane.org; Fri, 05 Jun 2009 11:40:40 -0400 Original-Path: news.stanford.edu!headwall.stanford.edu!news.glorb.com!news2.glorb.com!proxad.net!feeder1-2.proxad.net!cleanfeed3-a.proxad.net!nnrp6-2.free.fr!not-for-mail Original-Newsgroups: gnu.emacs.help Face: iVBORw0KGgoAAAANSUhEUgAAADAAAAAwAQMAAABtzGvEAAAABlBMVEUAAAD///+l2Z/dAAAA oElEQVR4nK3OsRHCMAwF0O8YQufUNIQRGIAja9CxSA55AxZgFO4coMgYrEDDQZWPIlNAjwq9 033pbOBPtbXuB6PKNBn5gZkhGa86Z4x2wE67O+06WxGD/HCOGR0deY3f9Ijwwt7rNGNf6Oac l/GuZTF1wFGKiYYHKSFAkjIo1b6sCYS1sVmFhhhahKQssRjRT90ITWUk6vvK3RsPGs+M1RuR mV+hO/VvFAAAAABJRU5ErkJggg== X-Accept-Language: fr, es, en X-Disabled: X-No-Archive: no User-Agent: Gnus/5.101 (Gnus v5.10.10) Emacs/22.2 (gnu/linux) Cancel-Lock: sha1:MzA2NWMyOWExMjY0NjdjMDVkNzhmMzk4ZDEwZDQzOWM4MTI4YWVlNw== Original-Lines: 39 Original-NNTP-Posting-Date: 05 Jun 2009 17:08:59 MEST Original-NNTP-Posting-Host: 88.170.236.224 Original-X-Trace: 1244214539 news-3.free.fr 27384 88.170.236.224:45538 Original-X-Complaints-To: abuse@proxad.net Original-Xref: news.stanford.edu gnu.emacs.help:169740 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:64971 Archived-At: Nordlöw writes: > I really believe such a function increases the readability of the code > that uses it, don't you? > What if I define it as a macro (defmacro) or inline (defsubst)? > Doesn't that give the best of both worlds+ Readability is somewhat in the eyes of the reader. That said, I can just repeat wat I wrote: setf is a standard and well known operator designed to assign a value to any kind of place, so it will be understood readily by any lisp programmer. Defining redundant and specific operators just give you more work -- if you change the type of a sequence between list and vector, you'll have to edit all the place where you used setnthcar or setnthref instead of (setf (elt ...) ...) -- and it will give more work to the reader who will have to refer to your functions definitions to know what they mean. If you were talking about a new kind of data structure, I'd agree that it would be ok to define a setter, but then it would have to be defined with the arguments in the 'correct' order: (defun set-my-own-data-structure (new-value data-structure index1 ...) ...) so you could bind it to setf: (defsetf my-own-data-structure set-my-own-data-structure) and right away forget about set-my-own-data-structure, but write: (setf (my-own-data-structure my-ds i...) new-value) -- __Pascal Bourguignon__