From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-3.9 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,RP_MATCHES_RCVD shortcircuit=no autolearn=ham autolearn_force=no version=3.4.0 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id 591A51FCA0 for ; Tue, 28 Mar 2017 05:17:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752848AbdC1FRe (ORCPT ); Tue, 28 Mar 2017 01:17:34 -0400 Received: from cloud.peff.net ([104.130.231.41]:52730 "EHLO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752760AbdC1FRe (ORCPT ); Tue, 28 Mar 2017 01:17:34 -0400 Received: (qmail 16255 invoked by uid 109); 28 Mar 2017 05:17:27 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.84) with SMTP; Tue, 28 Mar 2017 05:17:27 +0000 Received: (qmail 20513 invoked by uid 111); 28 Mar 2017 05:17:41 -0000 Received: from sigill.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.7) by peff.net (qpsmtpd/0.84) with SMTP; Tue, 28 Mar 2017 01:17:41 -0400 Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Tue, 28 Mar 2017 01:17:23 -0400 Date: Tue, 28 Mar 2017 01:17:23 -0400 From: Jeff King To: =?utf-8?B?w4Z2YXIgQXJuZmrDtnLDsA==?= Bjarmason Cc: Git Mailing List , Junio C Hamano , "brian m . carlson" , Matthieu Moy , Duy Nguyen , Brandon Williams Subject: Re: [PATCH/RFC] parse-options: add facility to make options configurable Message-ID: <20170328051723.h2xi2do6iclm64pi@sigill.intra.peff.net> References: <20170324231013.23346-1-avarab@gmail.com> <20170325213107.u2l5eunqgqbxpcbb@sigill.intra.peff.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Sat, Mar 25, 2017 at 11:32:02PM +0100, Ævar Arnfjörð Bjarmason wrote: > > So hopefully it's clear that the two are functionally equivalent, and > > differ only in syntax (in this case we manually decided which options > > are safe to pull from the config, but we'd have to parse the options.log > > string, too, and we could make the same decision there). > > I like the simplicity of this approach a lot. I.e. (to paraphrase it > just to make sure we're on the same page): Skip all the complexity of > reaching into the getopt guts, and just munge argc/argv given a config > we can stick ahead of the getopt (struct options) spec, inject some > options at the beginning if they're in the config, and off we go > without any further changes to the getopt guts. Yep, I think that's an accurate description. > There's two practical issues with this that are easy to solve with my > current approach, but I can't find an easy solution to using this > method. > > The first is that we're replacing the semantics of: > > "If you're specifying it on the command-line, we take it from there, > otherwise we use your config, if set, regardless of how the option > works" > > with: > > "We read your config, inject options implicitly at the start of the > command line, and then append whatever command-line you give us" > > These two are not the same. Consider e.g. the commit.verbose config. > With my current patch if have commit.verbose=1 in your config and do > "commit --verbose" you just end up with a result equivalent to not > having it in your config, but since the --verbose option can be > supplied multiple times to increase verbosity with the injection > method you'd end up with the equivalent of commit.verbose=2. Right, for anything where multiple options are meaningful, they'd have to give "--no-verbose" to reset the option. In a sense that's less friendly, because it's more manual. But it's also less magical, because the semantics are clear: the config option behaves exactly as if you gave the option on the command line. So for an OPT_STRING_LIST(), you could append to the list, or reset it to empty, etc, as you see fit. But I do agree that it's more manual, and probably would cause some confusion. > I can't think of a good way around that with your proposed approach > that doesn't essentially get us back to something very similar to my > patch, i.e. we'd need to parse the command-line using the options spec > before applying our implicit config. Yes, the semantics you gave require parsing the options first. I think it would be sufficient to just give each "struct option" a "seen" flag (rather than having it understand the config mechanism), having parse_options() set the flag, and then feeding the result to a separate config/cmdline mapping mechanism. That keeps the complexity out of the options code. It does tie us back in to requiring parse-options, which not all the options use. In a lot of cases that "seen" flag is effectively a sentinel value in whatever variable the option value is stored in. But some of the options don't have reasonable sentinel values (as you noticed with the "revert -m" handling recently). > The second issue is related, i.e. I was going to add some flag an > option could supply to say "if I'm provided none of these other > maybe-from-config options get to read their config". This is needed > for hybrid plumbing/porcelain like "git status --porcelain". Yeah, I agree you can't make that decision until you've seen the command-line options. I think we currently do some hairy stuff where we speculatively read config into a variable, and then apply the config-based defaults only when we know we're in non-porcelain mode (see status_deferred_config in builtin/commit.c). That came about because we didn't want to parse the config a second time. These days the deferred config should probably just be read from the cached configset, after we've read the other options. But I think this can be done after the full option-parsing is finished by applying the mapping then. I.e., something like: parse_options(argc, argv, options, ...); if (status_format != STATUS_FORMAT_PORCELAIN) apply_config_mapping(status_mapping, options); -Peff