Re: Add configuration options for some commonly used command-line options

From: "Ævar Arnfjörð Bjarmason" <avarab@gmail.com>
To: Junio C Hamano <gitster@pobox.com>
Cc: Brandon Williams <bmwill@google.com>,
	Duy Nguyen <pclouds@gmail.com>,
	"brian m. carlson" <sandals@crustytoothpaste.net>,
	Matthieu Moy <Matthieu.Moy@grenoble-inp.fr>,
	Jeff King <peff@peff.net>, Git Mailing List <git@vger.kernel.org>
Subject: Re: Add configuration options for some commonly used command-line options
Date: Mon, 20 Mar 2017 22:57:03 +0100	[thread overview]
Message-ID: <CACBZZX59KXPOEjiUKtZLN6zjO_xpiWve7Xga6q-53J2LwvfZyw@mail.gmail.com> (raw)
In-Reply-To: <xmqq7f3jwzdo.fsf@gitster.mtv.corp.google.com>

On Mon, Mar 20, 2017 at 7:56 PM, Junio C Hamano <gitster@pobox.com> wrote:
> One thing we may want to consider is why we have to even worry about
> scripts getting broken.  It is because people script around
> Porcelain, and that is because we have been too eager to improve
> Porcelain while neglecting plumbing for too long, to the point that
> some things are only doable with Porcelain (or doing the same with
> plumbing while possible are made too cumbersome).  I find it quite
> disturbing that nobody brought that up as an issue that needs to be
> addressed in this entire thread.

I very much doubt this describes anything but a tiny number of cases
where people are using the porcelain as an API.

People aren't going through the process of trying to find out how to
do something with a plumbing command, and then failing and falling
back to a porcelain command because the plumbing isn't complete
enough. They just use the porcelain because they're familiar with it
and scripting it works for them.

E.g. I just looked at both major Emacs modes for git now, magit &
vc-git, neither use "mktag", they just shell out to "git tag" for
making tags. I just went to the git-scm.com website and looked at one
open source GUI client I could "git clone", Giggle. It just shells out
to e.g. "git commit" to make commits, not "git commit-tree". The other
commands they're using are porcelain too. If they've used some
plumbing it's probably by sheer accident. E.g. they use ls-tree which
is plumbing, but don't use for-each-ref.

What's that Google SRE-ism again? Something like "People use the
reliability you provide them with in practice, not what you
advertise". Our porcelain is very stable, and so people use it as a
stable API, and not just for trivial scripts.

Which I think has some big implications for how we maintain the
porcelain & plumbing. Since people *will* use the porcelain, probably
no matter what we advertise to them or how good the plumbing is.