RE: [PATCH] config: add an includeIf.env{Exists,Bool,Is,Match}

From: "Randall S. Becker" <rsbecker@nexbridge.com>
To: "'Jeff King'" <peff@peff.net>
Cc: "'Junio C Hamano'" <gitster@pobox.com>,
	"'Ævar Arnfjörð Bjarmason'" <avarab@gmail.com>,
	git@vger.kernel.org, "'The Grey Wolf'" <greywolf@starwolf.com>
Subject: RE: [PATCH] config: add an includeIf.env{Exists,Bool,Is,Match}
Date: Mon, 27 Sep 2021 17:56:10 -0400	[thread overview]
Message-ID: <00f701d7b3ea$7eb59eb0$7c20dc10$@nexbridge.com> (raw)
In-Reply-To: <YVI5rYamHBkGQ/jy@coredump.intra.peff.net>

On September 27, 2021 5:38 PM, Jeff King wrote:
>Subject: Re: [PATCH] config: add an includeIf.env{Exists,Bool,Is,Match}
>
>On Mon, Sep 27, 2021 at 04:53:59PM -0400, Randall S. Becker wrote:
>
>> What about something like:
>>
>> 	[includeIf "env:PATH ~= '^(.*😊)/usr/bin(:.*)*$' "]
>>
>> Using single quotes and a full regex pattern instead of trying to
>> provide a syntax to extract a pattern and then match. One call to
>> regexec() would be easier. Then escaping is regcomp's problem
>> (mostly). Potentially, you could even remove the outer ", but that
>> would be wonky. You could omit the ^ and $ by default assuming a full
>> match.
>
>I almost suggested that, but then...how do you put single-quotes in your pattern? You can backslash-escape them, but:
>
>  - do you need to escape the backslash to get it through the config
>    parser intact?
>
>  - it seems extra funny to me because single quotes usually imply a
>    lack of interpolation

Exactly so. I think it would be more clear to have a regular expression be provided literally without interpretation other than by regcomp - other than the emergency ' escape, of course.