From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: X-Spam-Status: No, score=-3.8 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS shortcircuit=no autolearn=ham autolearn_force=no version=3.4.6 Received: from out1.vger.email (out1.vger.email [IPv6:2620:137:e000::1:20]) by dcvr.yhbt.net (Postfix) with ESMTP id C98191F428 for ; Thu, 23 Mar 2023 23:30:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231298AbjCWXav convert rfc822-to-8bit (ORCPT ); Thu, 23 Mar 2023 19:30:51 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57426 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229576AbjCWXat (ORCPT ); Thu, 23 Mar 2023 19:30:49 -0400 Received: from secure.elehost.com (secure.elehost.com [185.209.179.11]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 380DE28E5F for ; Thu, 23 Mar 2023 16:30:48 -0700 (PDT) X-Virus-Scanned: Debian amavisd-new at secure.elehost.com Received: from Mazikeen (cpebc4dfb928313-cmbc4dfb928310.cpe.net.cable.rogers.com [99.228.251.108] (may be forged)) (authenticated bits=0) by secure.elehost.com (8.15.2/8.15.2/Debian-22ubuntu3) with ESMTPSA id 32NNTuUV2921525 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Thu, 23 Mar 2023 23:29:57 GMT Reply-To: From: To: "'Felipe Contreras'" , Cc: "'demerphq'" , "'Junio C Hamano'" , "'Emily Shaffer'" , "'Git List'" , "'Jonathan Nieder'" , "'Jose Lopes'" , "'Aleksandr Mikhailov'" References: <4222af90-bd6b-d970-2829-1ddfaeb770bf@dunelm.org.uk> In-Reply-To: Subject: RE: Proposal/Discussion: Turning parts of Git into libraries Date: Thu, 23 Mar 2023 19:30:30 -0400 Organization: Nexbridge Inc. Message-ID: <008101d95ddf$7863d900$692b8b00$@nexbridge.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 8BIT X-Mailer: Microsoft Outlook 16.0 Thread-Index: AQG8LXqmDy16wlKS+NWZyvs9ueIudgFiwiOjAhx6XsUBunDI+AMx1EoXrwAHrFA= Content-Language: en-ca Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Thursday, March 23, 2023 7:22 PM, Felipe Contreras wrote: >On Sat, Feb 18, 2023 at 5:12 AM Phillip Wood wrote: >> >> On 18/02/2023 01:59, demerphq wrote: >> > On Sat, 18 Feb 2023 at 00:24, Junio C Hamano wrote: >> >> >> >> Emily Shaffer writes: >> >> >> >>> Basically, if this effort turns out not to be fruitful as a whole, >> >>> I'd like for us to still have left a positive impact on the codebase. >> >>> ... >> >>> So what's next? Naturally, I'm looking forward to a spirited >> >>> discussion about this topic - I'd like to know which concerns >> >>> haven't been addressed and figure out whether we can find a way >> >>> around them, and generally build awareness of this effort with the community. >> >> >> >> On of the gravest concerns is that the devil is in the details. >> >> >> >> For example, "die() is inconvenient to callers, let's propagate >> >> errors up the callchain" is an easy thing to say, but it would take >> >> much more than "let's propagate errors up" to libify something like >> >> check_connected() to do the same thing without spawning a separate >> >> process that is expected to exit with failure. >> > >> > >> > What does "propagate errors up the callchain" mean? One >> > interpretation I can think of seems quite horrible, but another >> > seems quite doable and reasonable and likely not even very invasive >> > of the existing code: >> > >> > You can use setjmp/longjmp to implement a form of "try", so that >> > errors dont have to be *explicitly* returned *in* the call chain. >> > And you could probably do so without changing very much of the >> > existing code at all, and maintain a high level of conceptual >> > alignment with the current code strategy. >> >> Using setjmp/longjmp is an interesting suggestion, I think lua does >> something similar to what you describe for perl. However I think both >> of those use a allocator with garbage collection. I worry that using >> longjmp in git would be more invasive (or result in more memory leaks) >> as we'd need to to guard each allocation with some code to clean it up >> and then propagate the error. That means we're back to manually >> propagating errors up the call chain in many cases. > >We could just use talloc [1]. talloc is not portable. This would break various platforms. --Randall