From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Stefan Monnier via "Emacs development discussions." Newsgroups: gmane.emacs.devel Subject: Re: macroexpand and bytecomp.el Date: Mon, 12 Feb 2024 16:24:07 -0500 Message-ID: References: <723bc16c-a73c-45a7-9362-99056261d932@Spark> Reply-To: Stefan Monnier Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Transfer-Encoding: 8bit Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="8713"; mail-complaints-to="usenet@ciao.gmane.io" User-Agent: Gnus/5.13 (Gnus v5.13) To: emacs-devel@gnu.org Cancel-Lock: sha1:Hn23H8F9CiAtVaNp3KdsgQtsorw= Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Mon Feb 12 22:25:08 2024 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 1rZdnX-00026v-C9 for ged-emacs-devel@m.gmane-mx.org; Mon, 12 Feb 2024 22:25:07 +0100 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rZdmm-00078W-6l; Mon, 12 Feb 2024 16:24:20 -0500 Original-Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rZdmk-00078G-JJ for emacs-devel@gnu.org; Mon, 12 Feb 2024 16:24:18 -0500 Original-Received: from ciao.gmane.io ([116.202.254.214]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rZdmj-0000n4-7v for emacs-devel@gnu.org; Mon, 12 Feb 2024 16:24:18 -0500 Original-Received: from list by ciao.gmane.io with local (Exim 4.92) (envelope-from ) id 1rZdmg-00010D-F3 for emacs-devel@gnu.org; Mon, 12 Feb 2024 22:24:14 +0100 X-Injected-Via-Gmane: http://gmane.org/ Received-SPF: pass client-ip=116.202.254.214; envelope-from=ged-emacs-devel@m.gmane-mx.org; helo=ciao.gmane.io X-Spam_score_int: -16 X-Spam_score: -1.7 X-Spam_bar: - X-Spam_report: (-1.7 / 5.0 requ) BAYES_00=-1.9, HEADER_FROM_DIFFERENT_DOMAINS=0.249, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Xref: news.gmane.io gmane.emacs.devel:316152 Archived-At: > (defmacro byte-extrude-byte-code-vectors () > (prog1 (list 'setq 'byte-code-vector > (get 'byte-code-vector 'tmp-compile-time-value) > 'byte-stack+-info > (get 'byte-stack+-info 'tmp-compile-time-value)) > (put 'byte-code-vector 'tmp-compile-time-value nil) > (put 'byte-stack+-info 'tmp-compile-time-value nil))) [...] > (defvar tmp-var [1 2 3]) > (defvar my-var nil) > (defmacro my-extrude () >  (prog1 (list 'setq 'my-var 'tmp-var) >  (setq tmp-var nil))) > (my-extrude) I don't fully understand your question, but notice that in your macro you use 'tmp-var in the `setq`, i.e. your macro returns code that uses the name of the variable and not its content (so the variable will be read *after* when the code is run rather than when it's macro-expanded), whereas in `byte-extrude-byte-code-vectors` the macro executes (get 'byte-code-vector 'tmp-compile-time-value) during the macro expansion and thus returns code which contains the value therein. IOW, `byte-extrude-byte-code-vectors` is more akin to: (defmacro my-extrude () (prog1 (list 'setq 'my-var tmp-var) (setq tmp-var nil))) - Stefan