Re: [PATCH 3/4] cat-file: add --batch-disk-sizes option

From: Jeff King <peff@peff.net>
Date: Jul 10, 2013, 11:16 UTC
Message-ID: <20130710111652.GE9724@sigill.intra.peff.net>
In-Reply-To: <CALkWK0k0xiNFaFmqL2t4ba2g+HSrQ8kU+W_HvnSMcMYY8VgJyg@mail.gmail.com>

On Mon, Jul 08, 2013 at 07:07:01PM +0530, Ramkumar Ramachandra wrote:

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> > There's also syntax sharing. I don't think each command should have
> > its own syntax. f-e-r already has %(objectsize). If we plan to have a
> > common syntax, perhaps %(disk-size) should be %(objectsize:disk) or
> > something.
> 
> Ofcourse.  I didn't notice %(objectsize); %(objectsize[:disk]) is a
> fine suggestion.
> 
> > Adding formatting to cat-file --batch from scratch could be
> > another big chunk of code (that also comes with bugs, usually) and may
> > or may not be compatible with the common syntax because of some
> > oversight.
> 
> Oh, I'm proposing that Peff implements just %H and
> %(objectsize[:disk]) for _now_, because that's what he wants.  It
> should be a tiny 20-line parser that's easy to swap out.

I went with %(objectname), %(objectsize), and %(objectsize:disk). The former match for-each-ref, and the latter extends it in a natural-ish way (though it is arguable whether "foo:modifier" should mean "do something with the foo value" or "this is like foo, but not quite"). In the long run, I would like to see long names for each atom, with short aliases (so "%H" and "%h" for "%(objectname) and "%(objectname:short)", available everywhere).

But I think it is OK to start without the aliases, and then pick them up as the implementations and interfaces are unified. IOW, it is OK to say "cat-file has not learned about %H yet", and later add it; we cannot teach it "%H" now and then change our minds later.

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> > --batch-cols=... or --batch-disk-size would be simpler, but
> > we might never be able to remove that code.
> 
> Agreed.  The approach paints us into a design-corner, and must
> therefore be avoided.

I would say it is worth one of the other routes if it turned out to be dramatically simpler. But having just done the work to add formats for cat-file, it is really not too bad. It lacks some of the niceties of the other formatters (e.g., colors), but again, we can always add them in later as the implementations unify.

-Peff