From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.io!.POSTED.blaine.gmane.org!not-for-mail From: Alan Mackenzie Newsgroups: gmane.emacs.devel Subject: buffer-string considered as a Bad Thing. Date: Tue, 4 Jun 2024 19:05:22 +0000 Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Injection-Info: ciao.gmane.io; posting-host="blaine.gmane.org:116.202.254.214"; logging-data="17589"; mail-complaints-to="usenet@ciao.gmane.io" To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane-mx.org@gnu.org Tue Jun 04 21:06:31 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 1sEZUM-0004OE-HK for ged-emacs-devel@m.gmane-mx.org; Tue, 04 Jun 2024 21:06:30 +0200 Original-Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1sEZTZ-0004dk-Fs; Tue, 04 Jun 2024 15:05:41 -0400 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 1sEZTX-0004dG-TP for emacs-devel@gnu.org; Tue, 04 Jun 2024 15:05:39 -0400 Original-Received: from mail.muc.de ([193.149.48.3]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1sEZTU-0000VD-Ru for emacs-devel@gnu.org; Tue, 04 Jun 2024 15:05:39 -0400 Original-Received: (qmail 62409 invoked by uid 3782); 4 Jun 2024 21:05:23 +0200 Original-Received: from muc.de (pd953a1a0.dip0.t-ipconnect.de [217.83.161.160]) (using STARTTLS) by colin.muc.de (tmda-ofmipd) with ESMTP; Tue, 04 Jun 2024 21:05:22 +0200 Original-Received: (qmail 11199 invoked by uid 1000); 4 Jun 2024 19:05:22 -0000 Content-Disposition: inline X-Submission-Agent: TMDA/1.3.x (Ph3nix) X-Primary-Address: acm@muc.de Received-SPF: pass client-ip=193.149.48.3; envelope-from=acm@muc.de; helo=mail.muc.de X-Spam_score_int: -18 X-Spam_score: -1.9 X-Spam_bar: - X-Spam_report: (-1.9 / 5.0 requ) BAYES_00=-1.9, SPF_HELO_PASS=-0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 autolearn=ham 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:319825 Archived-At: Hello, Emacs. In master (or any other non-prehistoric version of Emacs), buffer-string gets misused. In particular, function attempting to "print to a string" first print to a temporary buffer, then call buffer-string to get that printed object into the string. As an example, in pp, the function pp-to-string does this. To see the effect, try M-: (pp "foo \"bar\" baz") .. This gets printed correctly to the temporary buffer *temp* as: "foo \"bar\" baz" ;; (a 13 character string) , but buffer-string wrongly converts those literal characters to "foo \\\"bar\\\" baz" ;; (a 15 character string) .. Printing to a temporary buffer then converting that to a string (without reading it) appears to be a workaround for the Emacs core failing to allow a string as a possibility for PRINTCHARFUN in functions like prin1 and princ. An ideal solution seems to be somehow allowing a string to be PRINTCHARFUN for these functions. However print1 and friends don't return values; instead they append to buffers or output to output streams like stdout. Allowing a string output would be somewhat awkward. If this awkwardness rules out output to strings, we need better machinery than buffer-string to get a correct string from a buffer. We need to expose some more functionality from the reader to Lisp. With that we could write a function for filter-buffer-substring-function and thus correctly convert the temp buffer back to a string. Or something like that. Before I raise a bug report, what do people think about this? -- Alan Mackenzie (Nuremberg, Germany).