From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Stefan Monnier Newsgroups: gmane.emacs.devel Subject: Re: `aset` on strings, changing the size in bytes Date: Sat, 08 Sep 2018 14:36:46 -0400 Message-ID: References: <88must56x4.fsf@gnu.org> <83efe4trsa.fsf@gnu.org> <83lg8bsvfm.fsf@gnu.org> NNTP-Posting-Host: blaine.gmane.org Mime-Version: 1.0 Content-Type: text/plain X-Trace: blaine.gmane.org 1536432265 2308 195.159.176.226 (8 Sep 2018 18:44:25 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 8 Sep 2018 18:44:25 +0000 (UTC) User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/27.0.50 (gnu/linux) To: emacs-devel@gnu.org Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Sep 08 20:44:21 2018 Return-path: Envelope-to: ged-emacs-devel@m.gmane.org Original-Received: from lists.gnu.org ([208.118.235.17]) by blaine.gmane.org with esmtp (Exim 4.84_2) (envelope-from ) id 1fyiDU-0000Qz-84 for ged-emacs-devel@m.gmane.org; Sat, 08 Sep 2018 20:44:20 +0200 Original-Received: from localhost ([::1]:44885 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fyi7A-0007bN-MO for ged-emacs-devel@m.gmane.org; Sat, 08 Sep 2018 14:37:48 -0400 Original-Received: from eggs.gnu.org ([2001:4830:134:3::10]:35572) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fyi6L-000722-TC for emacs-devel@gnu.org; Sat, 08 Sep 2018 14:36:58 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fyi6I-0003Zs-Lj for emacs-devel@gnu.org; Sat, 08 Sep 2018 14:36:57 -0400 Original-Received: from [195.159.176.226] (port=44393 helo=blaine.gmane.org) by eggs.gnu.org with esmtps (TLS1.0:RSA_AES_128_CBC_SHA1:16) (Exim 4.71) (envelope-from ) id 1fyi6I-0003VR-Ds for emacs-devel@gnu.org; Sat, 08 Sep 2018 14:36:54 -0400 Original-Received: from list by blaine.gmane.org with local (Exim 4.84_2) (envelope-from ) id 1fyi49-0007il-S9 for emacs-devel@gnu.org; Sat, 08 Sep 2018 20:34:41 +0200 X-Injected-Via-Gmane: http://gmane.org/ Original-Lines: 20 Original-X-Complaints-To: usenet@blaine.gmane.org Cancel-Lock: sha1:eS2Bu01IhBkDvl1dJJRou/AtuZc= X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 195.159.176.226 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:229512 Archived-At: > That's not my reading of the code. It doesn't seem to cons a new > string. It does not allocate a new Lisp_String object, but it does allocate a new sdata object. Allocating a new Lisp_Object is not really an option, because `aset` couldn't return that new object (it has to work in-place). > But if I'm mistaken, and the current implementation does cons a new > string, then what is your problem with it? The need for an indirection (a String_Object has to hold a pointer to an sdata object rather than being able to keep its payload directly in the Lisp_String object (using FLEXIBLE_ARRAY_MEMBER)) and the unexpected memory allocation behavior (users who aren't privy to the underlying implementation would never expect a primitive like `aset` to internally perform a copy of the string's bytes). Stefan