From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.help Subject: Re: Concern around use of eval Date: Thu, 19 Mar 2015 10:07:55 -0400 Message-ID: References: NNTP-Posting-Host: plane.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: ger.gmane.org 1426774148 19459 80.91.229.3 (19 Mar 2015 14:09:08 GMT) X-Complaints-To: usenet@ger.gmane.org NNTP-Posting-Date: Thu, 19 Mar 2015 14:09:08 +0000 (UTC) To: help-gnu-emacs@gnu.org Original-X-From: help-gnu-emacs-bounces+geh-help-gnu-emacs=m.gmane.org@gnu.org Thu Mar 19 15:09:01 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 1YYb88-0008T1-4i for geh-help-gnu-emacs@m.gmane.org; Thu, 19 Mar 2015 15:09:00 +0100 Original-Received: from localhost ([::1]:39347 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YYb87-0004I7-Dm for geh-help-gnu-emacs@m.gmane.org; Thu, 19 Mar 2015 10:08:59 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:60678) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YYb7c-000497-Jv for help-gnu-emacs@gnu.org; Thu, 19 Mar 2015 10:08:36 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1YYb7N-0000Mk-Ul for help-gnu-emacs@gnu.org; Thu, 19 Mar 2015 10:08:28 -0400 Original-Received: from plane.gmane.org ([80.91.229.3]:38376) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1YYb7N-0000M3-NC for help-gnu-emacs@gnu.org; Thu, 19 Mar 2015 10:08:13 -0400 Original-Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1YYb7L-0007sp-7E for help-gnu-emacs@gnu.org; Thu, 19 Mar 2015 15:08:11 +0100 Original-Received: from 69-165-152-31.dsl.teksavvy.com ([69.165.152.31]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 19 Mar 2015 15:08:11 +0100 Original-Received: from monnier by 69-165-152-31.dsl.teksavvy.com with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Thu, 19 Mar 2015 15:08:11 +0100 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 34 Original-X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: 69-165-152-31.dsl.teksavvy.com User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.0.50 (gnu/linux) Cancel-Lock: sha1:AytUlscrELABMjFZBdfVN6/PRDM= X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 80.91.229.3 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:103216 Archived-At: > | (defvar lh/labels '("label1" "label2" "label3")) > | > | (defmacro lh/gen-predicate (label) > | `(defun ,(intern (concat "lh/" label "-p")) () > | (member ,label *lh/system-label-store*))) > | > | (defun lh/define-predicates () > | (dolist (label lh/labels) > | (eval `(lh/gen-predicate ,label)))) > | (lh/define-predicates) ; -*- lexical-binding:t -*- (defvar lh/labels '("label1" "label2" "label3")) (defun lh/gen-predicate (label) (defalias (intern (concat "lh/" label "-p")) (lambda () (member label *lh/system-label-store*)))) (defun lh/define-predicates () (mapc #'lh/gen-predicate lh/labels)) (lh/define-predicates) > Stylistically, is there a better way to do this or am I just being > weird about (eval) and should just get over it? You're not weird about `eval'. It's kind of like self-modifying code: there are cases where you *really* need it, but they're extremely rare and every time you use it when it's not *really* indispensable, kittens die. Stefan