From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: Lexical binding: why? Date: Tue, 28 May 2019 13:21:22 -0400 Message-ID: References: <20190528100850.GA5296@ACM> <20190528134451.GB5296@ACM> Mime-Version: 1.0 Content-Type: text/plain Injection-Info: blaine.gmane.org; posting-host="blaine.gmane.org:195.159.176.226"; logging-data="126107"; mail-complaints-to="usenet@blaine.gmane.org" User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) Cc: emacs-devel@gnu.org To: Alan Mackenzie Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Tue May 28 19:22:13 2019 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([209.51.188.17]) by blaine.gmane.org with esmtps (TLS1.0:RSA_AES_256_CBC_SHA1:256) (Exim 4.89) (envelope-from ) id 1hVfng-000Wdm-Bo for ged-emacs-devel@m.gmane.org; Tue, 28 May 2019 19:22:12 +0200 Original-Received: from localhost ([127.0.0.1]:39982 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hVfne-0006l2-HZ for ged-emacs-devel@m.gmane.org; Tue, 28 May 2019 13:22:10 -0400 Original-Received: from eggs.gnu.org ([209.51.188.92]:39262) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1hVfn4-0006kn-Sz for emacs-devel@gnu.org; Tue, 28 May 2019 13:21:35 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1hVfn3-0003y0-TS for emacs-devel@gnu.org; Tue, 28 May 2019 13:21:34 -0400 Original-Received: from mailscanner.iro.umontreal.ca ([132.204.25.50]:1971) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1hVfn3-0003pv-KP for emacs-devel@gnu.org; Tue, 28 May 2019 13:21:33 -0400 Original-Received: from pmg1.iro.umontreal.ca (localhost.localdomain [127.0.0.1]) by pmg1.iro.umontreal.ca (Proxmox) with ESMTP id 2D6B4101204; Tue, 28 May 2019 13:21:25 -0400 (EDT) Original-Received: from mail02.iro.umontreal.ca (unknown [172.31.2.1]) by pmg1.iro.umontreal.ca (Proxmox) with ESMTP id 734671011B6; Tue, 28 May 2019 13:21:23 -0400 (EDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=iro.umontreal.ca; s=mail; t=1559064083; bh=+H++Wz9N27rISvQ3tVtu8bTKH3gCmoF/PG92eQ+pseE=; h=From:To:Cc:Subject:References:Date:In-Reply-To:From; b=ja0CG1uyx5hpMe1ruOoXIBUhlJ/V8msYN5LHzFBxglNc7seIzh09yW2OE8ZC/ass8 VqvwZR2WyzToP1odoas8j0BUUYtg/9RzdSJghWPnt3f1+I0oQRd4FBujncfv7vq+fq j7RQ/IWrwdj66iNweXEsnzvnjWVWdoVI0twK4GmPQpmnjlbrQ6Q3PjgFBxHxQQPPZa 0p45rZZycIfOQVEDV8TXxV6p+3QlK3/Vv13mwJGBXlW1c5FRAQXUr2oL4nMHsQJKFz 0nHj4gRh61ggtCigyPgbY+kh6RLxxESbex8vRrMRmCMXLX3HdeqADfwaD6tjg8VZno abxW9jqkSPoMw== Original-Received: from alfajor (192-171-44-92.cpe.pppoe.ca [192.171.44.92]) by mail02.iro.umontreal.ca (Postfix) with ESMTPSA id 4AA40120775; Tue, 28 May 2019 13:21:23 -0400 (EDT) In-Reply-To: <20190528134451.GB5296@ACM> (Alan Mackenzie's message of "Tue, 28 May 2019 13:44:51 +0000") X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 132.204.25.50 X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.21 Precedence: list List-Id: "Emacs development discussions." List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.org gmane.emacs.devel:237112 Archived-At: > Just in passing, the Elisp manual doesn't seem to be as helpful as it > might be, here. It doesn't positively recommend using lexical binding > in new programs, for example. Thanks for the heads up. > Just in passing2, it seems to be difficult to enable lexical binding > conditionally. The best that I can come up with is something like: > > -*- eval: (setq lexical-binding (> emacs-major-version 25)) -*- Hmm... why do you need that? Is that because of a performance problem in Emacs-24's lexical-binding support (likely the one that affects condition-case and friends)? Stefan