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Date:   Wed, 10 Mar 2021 17:19:44 -0500
From:   Jeff King <peff@peff.net>
To:     Taylor Blau <me@ttaylorr.com>
Cc:     Patrick Steinhardt <ps@pks.im>, git@vger.kernel.org,
        Christian Couder <christian.couder@gmail.com>
Subject: Re: [PATCH 0/7] rev-parse: implement object type filter
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On Wed, Mar 10, 2021 at 04:58:16PM -0500, Taylor Blau wrote:

> On Mon, Mar 01, 2021 at 01:20:26PM +0100, Patrick Steinhardt wrote:
> > - A new object type filter `--filter=object:type=<type>` for
> >   git-rev-list(1), which is implemented both for normal graph walks and
> >   for the packfile bitmap index.
> 
> I understand what you're looking for here, but I worry that '--filter'
> might be too leaky of an abstraction.
> 
> I was a little surprised to learn that you can clone a repository with
> --filter=object:type=tree (excluding commits), but it does work. I'm
> fine reusing a lot of the object filtering code if it makes this an
> easier task, but I think it may be worthwhile to hide this new kind of
> filter from upload-pack.

I had a similar thought, but wouldn't the existing uploadpackfilter
config take care of this?

I guess the catch-all "allow" option defaults to "true", so we'd support
any new filters that are added. Which seems like a poor choice in
general, but flipping it would mean that servers have to update their
config.

I do wonder if it's that bad for clients to be able to specify something
like this, though. Even though there's not that much use for it with a
regular partial clone, it could conceivably used for some special cases.
I do think it would be more useful if you could OR together multiple
types. Asking for "commits|tags|trees" is really the same as the already
useful "blob:none". And "commits|tags" is the same as tree:depth=0.

-Peff