From mboxrd@z Thu Jan 1 00:00:00 1970 Path: news.gmane.org!.POSTED!not-for-mail From: Eli Zaretskii Newsgroups: gmane.emacs.devel Subject: Re: `aset` on strings, changing the size in bytes Date: Sat, 08 Sep 2018 23:59:47 +0300 Message-ID: <83k1nvso1o.fsf@gnu.org> References: <88must56x4.fsf@gnu.org> <83efe4trsa.fsf@gnu.org> <83lg8bsvfm.fsf@gnu.org> NNTP-Posting-Host: blaine.gmane.org X-Trace: blaine.gmane.org 1536440270 28746 195.159.176.226 (8 Sep 2018 20:57:50 GMT) X-Complaints-To: usenet@blaine.gmane.org NNTP-Posting-Date: Sat, 8 Sep 2018 20:57:50 +0000 (UTC) Cc: emacs-devel@gnu.org To: Stefan Monnier Original-X-From: emacs-devel-bounces+ged-emacs-devel=m.gmane.org@gnu.org Sat Sep 08 22:57:46 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 1fykIb-0007P0-JE for ged-emacs-devel@m.gmane.org; Sat, 08 Sep 2018 22:57:45 +0200 Original-Received: from localhost ([::1]:45216 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fykKe-00033L-RX for ged-emacs-devel@m.gmane.org; Sat, 08 Sep 2018 16:59:52 -0400 Original-Received: from eggs.gnu.org ([208.118.235.92]:48902) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fykKZ-00033E-1u for emacs-devel@gnu.org; Sat, 08 Sep 2018 16:59:47 -0400 Original-Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fykKV-00065Z-TV for emacs-devel@gnu.org; Sat, 08 Sep 2018 16:59:47 -0400 Original-Received: from fencepost.gnu.org ([2001:4830:134:3::e]:54831) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fykKV-00065S-OY; Sat, 08 Sep 2018 16:59:43 -0400 Original-Received: from [176.228.60.248] (port=1382 helo=home-c4e4a596f7) by fencepost.gnu.org with esmtpsa (TLS1.2:RSA_AES_256_CBC_SHA1:256) (Exim 4.82) (envelope-from ) id 1fykKV-00057h-9C; Sat, 08 Sep 2018 16:59:43 -0400 In-reply-to: (message from Stefan Monnier on Sat, 08 Sep 2018 14:36:46 -0400) X-detected-operating-system: by eggs.gnu.org: GNU/Linux 2.2.x-3.x [generic] X-Received-From: 2001:4830:134:3::e 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:229517 Archived-At: > From: Stefan Monnier > Date: Sat, 08 Sep 2018 14:36:46 -0400 > > 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)) Why is that a problem? > 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). Only C-level programming sees that, and it will never see it if strings are treated like buffers, i.e. not passed as C pointers to text. So I don't see why this would be a problem, given the small number of people who work at that level, and an even smaller number of people who make changes in the low-level code which depends on that.