Re: [PATCH v4 31/45] rebase: trivial cleanup

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 11, 2013, 16:12 UTC
Message-ID: <7vhah4d3sk.fsf@alter.siamese.dyndns.org>
In-Reply-To: <20130609191518.GB12122@paksenarrion.iveqy.com>

Fredrik Gustafsson <iveqy@iveqy.com> writes:

> Here we have two sh-scripts (git rebase
> and git am) interacting with each other.
> Both uses GIT_QUIET,

Correct.

> so if GIT_QUIET already is set by the caller (git rebase) the
> callee doesn't have to set it to.

Incorrect. "git rebase" invokes "git am", not dot-sources it, so it does not propagate.

Both do dot-source git-sh-setup, which clears GIT_QUIET pretty early, so even GIT_QUIET exported into the environment by mistake will not affect them.

> However GIT_QUIET is undocumented for git-am (in Git Manual). If we
> translate git am to C/ruby/python/perl/etc. will we catch this?

I think it is irrelevant. git-am uses many shell variables, e.g. HAS_HEAD, interactive, abort_safety, etc. but they are implementation details of the program and there is no point documenting it, and somebody rewriting it in C does not have to stick to the same name.

What may deserve to be documented in Documentation/technical/ somewhere is the way how some shell variables (OPTIONS_SPEC, OPTIONS_KEEPDASHDASH, LONG_USAGE, USAGE, GIT_REFLOG_ACTION, etc.) are used in git-sh-setup, which is a collection of helper shell functions for use in scripted Porcelains that dot-source it. It allows the scripted Porcelains to say things like:

	die "message"
        say "message"

and the latter pays attention to GIT_QUIET.

> This raises a few more generall questions:
> do we already pass information between processes(!) with enviroment
> variables? And is this documented the way it should be?

There are a few used as implementation details, I think. GIT_QUIET is not among them.