From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Jeff King <peff@peff.net>
Cc: Junio C Hamano <gitster@pobox.com>,
Patrick Steinhardt <ps@pks.im>,
git@vger.kernel.org
Subject: Re: [PATCH 2/2] config: allow specifying config entries via envvar pairs
Date: Wed, 18 Nov 2020 14:44:59 +0100 [thread overview]
Message-ID: <87ft56rd7o.fsf@evledraar.gmail.com> (raw)
In-Reply-To: <20201117235736.GC642410@coredump.intra.peff.net>
On Wed, Nov 18 2020, Jeff King wrote:
> On Tue, Nov 17, 2020 at 03:22:05PM +0100, Ævar Arnfjörð Bjarmason wrote:
>
>> > then I'd feel comfortable making it a public-facing feature. And for
>> > most cases it would be pretty pleasant to use (and for the unpleasant
>> > ones, I'm not sure that a little quoting is any worse than the paired
>> > environment variables found here).
>>
>> I wonder if something like the git config -z format wouldn't be easier,
>> with the twist that we'd obviously not support \0. So we'd need an
>> optional length prefix. : = unspecified.
>>
>> :user.name
>> Jeff K
>> :alias.ci
>> commit
>> :10:bin.ary
>> <10 byte string, might have a \n>
>> :other.key
>> Other Value
>>
>> Maybe that's overly fragile, or maybe another format would be better.
>
> Yeah, length-delimited strings are an alternative that some people think
> is less error-prone than quoting. And we do use pkt-lines. They're also
> a pain for humans to write (it's nicer if they're optional, but when you
> _do_ have to start using them, now you are stuck counting things up).
>
>> I was trying to come up with one where the common case wouldn't
>> require knowing about shell quoting/unquoting, and where you could
>> still do:
>>
>> GIT_CONFIG_PARAMETERS=":my.new\nvalue\n$GIT_CONFIG_PARAMETERS"
>>
>> Or equivalent, and still just keep $GIT_CONFIG_PARAMETERS as-is to pass
>> it along.
>>
>> Your "do not require quoting" accomplishes that, and it's arguably a lot
>n
> Looks like your mail got cut off.
Nothing important, probably :)
> But yeah, the goal of making the quoting optional was to make it
> easier for humans to use for simple cases. It doesn't help at all with
> other programs inserting values, which can just as easily err on the
> side of caution.
>
> BTW, there is another problem with GIT_CONFIG_PARAMETERS (and "git -c"
> in general). The dotted config-key format:
>
> section.subsection.key
>
> is unambiguous by itself, even though "subsection" can contain arbitrary
> bytes, including dots. Because neither "section" nor "key" can contain
> dots, we can parse from either end, and take the whole middle as a
> subsection (and this is how we do it in the code).
>
> But an assignment string like:
>
> section.subsection.key=value
>
> _is_ ambiguous. We have to parse left-to-right up to the first equals
> (since "value" can contain arbitrary characters, including an equals).
> But "subsection" can have one, too, so we want to parse right-to-left
> there. E.g., in:
>
> one.two=three.four=five
>
> this could be either of:
>
> - section is "one", key is "two", value is "three.four=five"
>
> - section is "one", subsection is "two=three", key is "four", value is
> "five"
>
> We currently always parse it as the former (which I think is least-bad
> of the two, since values are more likely than subsections to contain
> arbitrary text with an equals).
Yeah, it's a pain to parse if it's on one line. FWIW that's the main
reason for why the format I suggested moved it to \n-delimited, because
keys can't contain an \n, so you can unambiguously have them be
\n-delimited (as git config -z does).
You do need to worry about a \n in the value, but for the common case
where you don't have a \n there we wouldn't need to provide the length.
Or just provide tooling as you suggested in
<20201118015907.GD650959@coredump.intra.peff.net>, which I like better
than any one format suggestion (including the one I suggsted). I.e. we
can document that:
- The variable exists
- You read/write/add to it using a return value from this tool
Which allows for keeping the value itself opaque and open to a future
change.
next prev parent reply other threads:[~2020-11-18 13:46 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-13 12:16 [PATCH 0/2] config: allow specifying config entries via envvar pairs Patrick Steinhardt
2020-11-13 12:16 ` [PATCH 1/2] config: extract function to parse config pairs Patrick Steinhardt
2020-11-13 12:16 ` [PATCH 2/2] config: allow specifying config entries via envvar pairs Patrick Steinhardt
2020-11-13 13:04 ` Ævar Arnfjörð Bjarmason
2020-11-16 19:39 ` Junio C Hamano
2020-11-17 2:34 ` Jeff King
2020-11-17 6:37 ` Patrick Steinhardt
2020-11-17 7:01 ` Jeff King
2020-11-17 14:22 ` Ævar Arnfjörð Bjarmason
2020-11-17 23:57 ` Jeff King
2020-11-18 13:44 ` Ævar Arnfjörð Bjarmason [this message]
2020-11-18 0:50 ` brian m. carlson
2020-11-18 1:59 ` Jeff King
2020-11-18 2:25 ` brian m. carlson
2020-11-18 7:04 ` Patrick Steinhardt
2020-11-19 2:11 ` brian m. carlson
2020-11-19 6:37 ` Patrick Steinhardt
2020-11-18 5:44 ` Junio C Hamano
2020-11-17 6:28 ` Patrick Steinhardt
2020-11-17 7:06 ` Junio C Hamano
2020-11-18 13:49 ` Ævar Arnfjörð Bjarmason
2020-11-18 13:56 ` Patrick Steinhardt
2020-11-18 16:01 ` Junio C Hamano
2020-11-17 14:03 ` Ævar Arnfjörð Bjarmason
2020-11-13 16:37 ` Philip Oakley
2020-11-17 6:40 ` Patrick Steinhardt
2020-11-13 13:11 ` [PATCH 0/2] " Ævar Arnfjörð Bjarmason
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