Re: Design of multiple hash support

From: brian m. carlson <sandals@crustytoothpaste.net>
Date: Nov 6, 2018, 00:13 UTC
Message-ID: <20181106001340.GC890086@genre.crustytoothpaste.net>
In-Reply-To: <20181105220042.GA162375@google.com>

On Mon, Nov 05, 2018 at 02:00:42PM -0800, Jonathan Nieder wrote:

Show 25 quoted lines

> Hi,
> 
> Duy Nguyen wrote:
> > On Mon, Nov 5, 2018 at 2:02 AM brian m. carlson
> > <sandals@crustytoothpaste.net> wrote:
> 
> >> There are basically two approaches I can take.  The first is to provide
> >> each command that needs to learn about this with its own --hash
> >> argument.  So we'd have:
> >>
> >>   git init --hash=sha256
> >>   git show-index --hash=sha256 <some-file
> >>
> >> The other alternative is that we provide a global option to git, which
> >> is parsed by all programs, like so:
> >>
> >>   git --hash=sha256 init
> >>   git --hash=sha256 show-index <some-file
> [...]
> > I'm leaning towards "git foo --hash=".
> 
> Can you say a little more about the semantics of the option?  For
> commands like "git init", I tend to agree with Duy here, since it
> allows each command's manual to describe what the option means in the
> context of that command.

Sure. The semantics for git init are "produce a repository with this hash algorithm". The semantics for git index-pack are "the pack I want you to index uses this hash algorithm". Essentially, more generically, the semantics are "the repository or data object uses this hash algorithm".

> For "git show-index", ideally Git should use the object format named
> in the idx file.

I agree that will be the eventual goal. It will also be what I ship in the final series, in all likelihood. I have most of pack v3 implemented, but it's not complete yet.

-- 
brian m. carlson: Houston, Texas, US
OpenPGP: https://keybase.io/bk2204