From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: "Pascal J. Bourguignon" Newsgroups: gmane.emacs.help Subject: Re: How to delete all nil properties from a plist? Date: Sun, 02 Aug 2015 03:36:22 +0200 Organization: Informatimago Message-ID: <871tfmv5d5.fsf@kuiper.lan.informatimago.com> References: <87oaiq3buh.fsf@mbork.pl> <87mvya3bij.fsf@mbork.pl> NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Trace: ger.gmane.org 1438479618 9711 80.91.229.3 (2 Aug 2015 01:40:18 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Sun, 2 Aug 2015 01:40:18 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Sun Aug 02 03:40:17 2015 Return-path: Envelope-to: geh-help-gnu-emacs@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by plane.gmane.org with esmtp (Exim 4.69) (envelope-from ) id 1ZLiG8-0000Xn-Om for geh-help-gnu-emacs@m.gmane.org; Sun, 02 Aug 2015 03:40:16 +0200 Original-Received: from localhost ([::1]:55055 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZLiG7-0006sm-R7 for geh-help-gnu-emacs@m.gmane.org; Sat, 01 Aug 2015 21:40:15 -0400 Original-Path: usenet.stanford.edu!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail Original-Newsgroups: gnu.emacs.help Original-Lines: 34 Original-X-Trace: individual.net FHBSQE+aFthuGtn2Kw3MpQqFSKjEi0LgxY2RsIVxZA/3rk+y5o Cancel-Lock: sha1:NDlhYTMwYjVjNTk4YmRkOWYzYWJkODM2Njk5ZTRjMGU0NjhmZjc4ZA== sha1:JZ+4/Z7KADO/g8EPcAnknufUjE4= Face: iVBORw0KGgoAAAANSUhEUgAAADAAAAAwAQMAAABtzGvEAAAABlBMVEUAAAD///+l2Z/dAAAA oElEQVR4nK3OsRHCMAwF0O8YQufUNIQRGIAja9CxSA55AxZgFO4coMgYrEDDQZWPIlNAjwq9 033pbOBPtbXuB6PKNBn5gZkhGa86Z4x2wE67O+06WxGD/HCOGR0deY3f9Ijwwt7rNGNf6Oac l/GuZTF1wFGKiYYHKSFAkjIo1b6sCYS1sVmFhhhahKQssRjRT90ITWUk6vvK3RsPGs+M1RuR mV+hO/VvFAAAAABJRU5ErkJggg== X-Accept-Language: fr, es, en User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.3 (gnu/linux) Original-Xref: usenet.stanford.edu gnu.emacs.help:213917 X-BeenThere: help-gnu-emacs@gnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Users list for the GNU Emacs text editor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Original-Sender: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Xref: news.gmane.org gmane.emacs.help:106202 Archived-At: Emanuel Berg writes: > Marcin Borkowski writes: > >>> Hi all, so I'm still using plists, though I'm less >>> and less sure that they are actually better than >>> alists for my use-case. Now I need to delete all >>> properties whose value is nil. I'm using this >>> function: > > Try this: > > (require 'cl) > > (defun plist-drop-nil-props (l) > (let((new) > (prop nil) ) > (cl-loop for x in l > do (if (or (setq prop (not prop)) x) > (setq new (append new (list x))) > (setq new (butlast new)))) > new)) This is horrible. Again, you can't prevent yourself writing O(n²) code when O(n) would do perfectly. -- __Pascal Bourguignon__ http://www.informatimago.com/ “The factory of the future will have only two employees, a man and a dog. The man will be there to feed the dog. The dog will be there to keep the man from touching the equipment.” -- Carl Bass CEO Autodesk