From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: LdBeth Newsgroups: gmane.emacs.devel Subject: Re: using finalizers Date: Fri, 31 Dec 2021 10:46:20 +0800 Message-ID: References: <878rw1pvcw.fsf@logand.com> Mime-Version: 1.0 (generated by SEMI-EPG 1.14.7 - "Harue") Content-Type: text/plain; charset=US-ASCII Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="26260"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Wanderlust/2.15.9 (Almost Unreal) SEMI-EPG/1.14.7 (Harue) FLIM-LB/1.14.9 (=?ISO-8859-4?Q?Goj=F2?=) APEL-LB/10.8 EasyPG/1.0.0 Emacs/27.2 (x86_64-apple-darwin18.7.0) MULE/6.0 (HANACHIRUSATO) Cc: emacs-devel@gnu.org To: Tomas Hlavaty Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Fri Dec 31 03:47:37 2021 Return-path: Envelope-to: ged-emacs-devel@m.gmane-mx.org Original-Received: from lists.gnu.org ([209.51.188.17]) by ciao.gmane.io with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.92) (envelope-from ) id 1n37xB-0006bT-2B for ged-emacs-devel@m.gmane-mx.org; Fri, 31 Dec 2021 03:47:37 +0100 Original-Received: from localhost ([::1]:48212 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1n37x9-0003Ji-8q for ged-emacs-devel@m.gmane-mx.org; Thu, 30 Dec 2021 21:47:35 -0500 Original-Received: from eggs.gnu.org ([209.51.188.92]:59070) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n37wI-0002TP-1X for emacs-devel@gnu.org; Thu, 30 Dec 2021 21:46:42 -0500 Original-Received: from out162-62-57-87.mail.qq.com ([162.62.57.87]:40727) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n37w6-00051J-MC for emacs-devel@gnu.org; Thu, 30 Dec 2021 21:46:34 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=foxmail.com; s=s201512; t=1640918782; bh=NciSHQJRGNcxKzAcKIF0XtDg1ci/2CnAnnefGPuXjhE=; h=Date:From:To:Cc:Subject:In-Reply-To:References; b=KLibG9ud9vyywYk4NxfW1if2ddodct6qJ6Ly8E+djBPdgMa3/nMO7YXFih+rgbixD W+aaOZRLdggDI15vs+21SX3WKL+1tapn9W/XryF8eBcBrl1Wbbc59dooOhyGYyZocF 4cxchskkUDWvPUt66/0RpZ06603od5FwZnL9rGMQ= Original-Received: from Costume-Party.local ([61.174.174.112]) by newxmesmtplogicsvrszc7.qq.com (NewEsmtp) with SMTP id B950C488; Fri, 31 Dec 2021 10:46:21 +0800 X-QQ-mid: xmsmtpt1640918781tf9vho1kf X-QQ-XMAILINFO: Mrgh6nGOssQak5g+frkflFLUJxJYG4GRSXkWMOQ30jsn75JSj8acQUfHk9yUs7 iWsz3LUSWW4Utb5aoQlGrKWS2/ikAdOqQ1mY16nU2mM3UCRF4mQNzTE1DFpuNhFaxVKUfo1/4DTM M7YrGzJWn2V3t3/M7H0PN5jmlKQ5j/zLW+I/wMuKFc6dxYkXwJ0WWUnnawZ8L7Qk9T4RtW6482yQ vrqfslf0wU9tdo41t+UKf+bASYop3p1b8xwVd9/QAfSWPWsK2BZ80hee0MQkTnFk3fIxLdWE+hMU GptUmpdf4pGJUxXEriFB9fxOhBI4DNw1AtBsLI2TKf9vzVo4Skh+zAtNnVXz9e7PxJ7ANmn2PyW2 PgfmYRHpw2Rj7XnXD1QuJK8hlRnjh5TXf0KM5o0knMBLcFHjo46YGHlXM3rWsfW3KmM3eOF8chfi EFVdO/A5r+GWNC8Pugcy9gVjqtc/DEfMujbS5zxxDJyskmNUiMQ+wA2/OelYM6FRQ0aIYj/r6eh7 YTP0RMCZ18XaHTniTkQTkcXqOWVquk4/wuY5p9I2uGkqk6dkbiEIkczfEHjqYS9O7Gk/XKev8YUW bE1BoS0L7PxjvFVcpxFM+1PcDEyiDgQtwDCcMS6NYJtoFiVxbIghEpMxqn4o36nIGUx1SyVQ4Xmu pnV9T8ay2V6x60zw+SvfJ5m/sE/yjLrCUjxhdcHtEavlTEoreiCnDgiVu8dV6s0I3MFpbRkSzmVE y/1YEhZBz5Z7+XLk+jajEsQ5aUVWPfniE+O+pnt0RsFSjlkkI5GxU40sLj38ugvOuSH1KG6t5vK0 Gfidmew949j2YHBLnVrW/5vEnivnm7gWvP2G/Jgl Original-Received: by Costume-Party.local (Postfix, from userid 501) id A5B41203D611DC; Fri, 31 Dec 2021 10:46:20 +0800 (CST) X-OQ-MSGID: In-Reply-To: <878rw1pvcw.fsf@logand.com> X-Face: %[!P\u/BKFRGn_9h9|yO"ho?C0ej^LmM}WMb-`Jfj8OsS^^AKmHYGlD@^|7SEA3UzOGPFbB"OFczY?'\JtJ\lR'@&Y5j; s8{$&|3D>^i.U4l2h?1qpD.+{[$~j]vBeHZf^|BGyL8{/`4 X-Attribution: ldb Received-SPF: pass client-ip=162.62.57.87; envelope-from=andpuke@foxmail.com; helo=out162-62-57-87.mail.qq.com X-Spam_score_int: 27 X-Spam_score: 2.7 X-Spam_bar: ++ X-Spam_report: (2.7 / 5.0 requ) DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001, HELO_DYNAMIC_IPADDR=1.951, MSGID_FROM_MTA_HEADER=0.001, RCVD_IN_DNSWL_NONE=-0.0001, RDNS_DYNAMIC=0.982, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=no autolearn_force=no X-Spam_action: no action X-BeenThere: emacs-devel@gnu.org X-Mailman-Version: 2.1.29 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-mx.org@gnu.org Original-Sender: "Emacs-devel" Xref: news.gmane.io gmane.emacs.devel:283695 Archived-At: >>>>> In <878rw1pvcw.fsf@logand.com> >>>>> Tomas Hlavaty wrote: > Hi, > I am trying to understand finalizers in Emacs Lisp but I am unable to > triger it. > Here is an example (with lexical-binding): > (defun finito () > (let ((x '(a b c))) > (letrec ((more (make-finalizer close)) > (close (lambda () > (print "close-resource") > (setq more nil)))) > (lambda () > (when more > (pop x)))))) > (setq foo (finito)) > (equal '(a b c nil nil) (mapcar (lambda (x) (funcall foo)) '(1 2 3 4 5))) > (setq foo nil) > (garbage-collect) > After garbage collection, I would expect to see close-resource text in > the *Messages* buffer but there is none. You are probably taking the wrong assumption about the effect of letrec (macroexpand '(letrec ((more (make-finalizer close)) (close (lambda () (setq bar t)))) (lambda () (when more (pop x))))) ==> (let (more close) (setq more (make-finalizer close)) (setq close (lambda nil (setq bar t))) (lambda nil (when more (pop x)))) So, `close' is nil and the lambda is never set as the finalizer. I think Common Lisp doesn't have letrec in the standard. And you are proabaly taking the assumption that ELisp's letrec works as well as Scheme's one. But it is not. > What is the expected example usage of finalizers in Emacs Lisp? > How can I verify, that my finalizer works? (setq bar nil) (setq foo (make-finalizer (lambda () (setq bar t)))) (setq foo nil) (garbage-collect) bar ; => t -- LDB