From: Jeff King <peff@peff.net>
To: Junio C Hamano <gitster@pobox.com>
Cc: Bryan Turner <bturner@atlassian.com>, Git Users <git@vger.kernel.org>
Subject: Re: Fully peel tags via for-each-ref?
Date: Thu, 22 Aug 2019 00:24:45 -0400 [thread overview]
Message-ID: <20190822042445.GB4347@sigill.intra.peff.net> (raw)
In-Reply-To: <xmqqmug1rj7y.fsf@gitster-ct.c.googlers.com>
On Wed, Aug 21, 2019 at 08:07:29PM -0700, Junio C Hamano wrote:
> But after we learn that a ref "refs/tags/foo" points at a tag object
> that points at another tag object, what can the script do? It
> cannot feed the other tag found that way back into --format=%(*<thing>)
> machinery of for-each-ref, as the command and its variants, the "--list"
> mode of "branch" and "tag" commands, only work on the object at the
> tip of refs. The script must manually peel the tag one layer at a time.
>
> And that "manually" has to be really manual. No ^{<type>} suffix
> allows scripts to peel just one layer, so inside a loop, the script
> has to say "cat-file tag <object>" and parse the "object" header
> from the output.
>
> The only thing that gets affected if we changed %(*<thing>) to fully
> peel tags is a tag that points at another tag, and the traditional
> behaviour to peel only one layer, while it _might_ have been done as
> a good first step to add more support for chain of trust, is not all
> that useful for such a tag, I am not sure if the current behaviour
> is defensible.
Yeah, well said, and I think this is the heart of the matter. There
isn't good tooling for this case, but even if there was, for-each-ref is
definitely not the place for it.
I took a brief look at making a patch, and it's unfortunately
non-trivial because of the way the deref logic in ref-filter is
implemented. So it may not be worth digging too far into for now if
nobody cares much either way.
I still have dreams of writing a more efficient and more reusable
version of ref-filter, and it would probably make sense to use
peel_ref() as part of that rewrite.
-Peff
prev parent reply other threads:[~2019-08-22 4:24 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-08-19 23:22 Fully peel tags via for-each-ref? Bryan Turner
2019-08-20 5:50 ` Junio C Hamano
2019-08-20 21:39 ` Bryan Turner
2019-08-21 23:00 ` Jeff King
2019-08-22 3:07 ` Junio C Hamano
2019-08-22 4:24 ` Jeff King [this message]
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