From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.2 (2018-09-13) on dcvr.yhbt.net X-Spam-Level: X-Spam-ASN: AS31976 209.132.180.0/23 X-Spam-Status: No, score=-4.0 required=3.0 tests=AWL,BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI shortcircuit=no autolearn=ham autolearn_force=no version=3.4.2 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by dcvr.yhbt.net (Postfix) with ESMTP id E9FDE20248 for ; Fri, 15 Mar 2019 03:17:08 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727022AbfCODRH (ORCPT ); Thu, 14 Mar 2019 23:17:07 -0400 Received: from cloud.peff.net ([104.130.231.41]:51856 "HELO cloud.peff.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1725991AbfCODRH (ORCPT ); Thu, 14 Mar 2019 23:17:07 -0400 Received: (qmail 14494 invoked by uid 109); 15 Mar 2019 03:17:08 -0000 Received: from Unknown (HELO peff.net) (10.0.1.2) by cloud.peff.net (qpsmtpd/0.94) with SMTP; Fri, 15 Mar 2019 03:17:08 +0000 Authentication-Results: cloud.peff.net; auth=none Received: (qmail 28619 invoked by uid 111); 15 Mar 2019 03:16:15 -0000 Received: from sigill.intra.peff.net (HELO sigill.intra.peff.net) (10.0.0.7) by peff.net (qpsmtpd/0.94) with (ECDHE-RSA-AES256-GCM-SHA384 encrypted) SMTP; Thu, 14 Mar 2019 23:16:15 -0400 Authentication-Results: peff.net; auth=none Received: by sigill.intra.peff.net (sSMTP sendmail emulation); Thu, 14 Mar 2019 23:15:53 -0400 Date: Thu, 14 Mar 2019 23:15:53 -0400 From: Jeff King To: Johannes Schindelin via GitGitGadget Cc: git@vger.kernel.org, Junio C Hamano , Johannes Schindelin Subject: Re: [PATCH v2 2/3] parse-options: make OPT_ARGUMENT() more useful Message-ID: <20190315031553.GB28943@sigill.intra.peff.net> References: <10775638ad8f2ef9b64b8dbaf71b80d8546e81d8.1552562701.git.gitgitgadget@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <10775638ad8f2ef9b64b8dbaf71b80d8546e81d8.1552562701.git.gitgitgadget@gmail.com> Sender: git-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: git@vger.kernel.org On Thu, Mar 14, 2019 at 04:25:04AM -0700, Johannes Schindelin via GitGitGadget wrote: > diff --git a/Documentation/technical/api-parse-options.txt b/Documentation/technical/api-parse-options.txt > index 2b036d7838..2e2e7c10c6 100644 > --- a/Documentation/technical/api-parse-options.txt > +++ b/Documentation/technical/api-parse-options.txt > @@ -198,8 +198,10 @@ There are some macros to easily define options: > The filename will be prefixed by passing the filename along with > the prefix argument of `parse_options()` to `prefix_filename()`. > > -`OPT_ARGUMENT(long, description)`:: > +`OPT_ARGUMENT(long, &int_var, description)`:: > Introduce a long-option argument that will be kept in `argv[]`. > + If this option was seen, `int_var` will be set to one (except > + if a `NULL` pointer was passed). So this effectively makes it into a "bool" that we keep. I think that's fine. It always uses NOARG, so it is not like we would ever need to see "we got --foo, and this is the argument it had". I did wonder if it was possible for "--no-foo" to trigger this (leaving the caller who looks at the int unsure if they saw "--foo" or "--no-foo"), but it seems that the parse-options code checks for OPTION_ARGUMENT before it ever looks at negation. Curiously, it also checks it before doing the usual prefix-matching magic. So you could otherwise say "--no-inde", but OPT_ARGUMENT() will not allow it. I think that's probably sane and not worth thinking further about, but it is an interesting quirk that a user could possibly run into. > diff --git a/parse-options.c b/parse-options.c > index cec74522e5..1d57802da0 100644 > --- a/parse-options.c > +++ b/parse-options.c > @@ -286,6 +286,8 @@ static enum parse_opt_result parse_long_opt( > optname(options, flags)); > if (*rest) > continue; > + if (options->value) > + *(int *)options->value = options->defval; Cute. You could actually assign any defval you like, though of course the convenient OPT_ARGUMENT() macro just always uses 1. I wondered if you might need another cast for defval itself, but it's an intptr_t (so it's the types that use it as a string that need to cast to "const char *"). This looks very clean overall, and I agree it's much nicer than the alternatives for your use case. -Peff