Re: [PATCH 2/4] builtin/rev-parse: learn --null-oid

From: Taylor Blau <me@ttaylorr.com>
Date: Sep 18, 2020, 14:11 UTC
Message-ID: <20200918141125.GB1602321@nand.local>
In-Reply-To: <004f2e4c92918a7a4e452d49e98ef15f1c5ac545.1600427894.git.liu.denton@gmail.com>

Hi Denton,

On Fri, Sep 18, 2020 at 04:19:03AM -0700, Denton Liu wrote:

Show 5 quoted lines

> When a user needed the null OID for scripting purposes, it used to be
> very easy: hardcode 40 zeros. However, since Git started supporting
> SHA-256, this assumption became false which may break some scripts.
> Allow users to fix their broken scripts by providing users with a
> hash-agnostic method of obtaining the null OID.

I have not been very involved in the hash transition, so please take my comments with a grain of salt (and if they are misplaced, feel free to ignore them).

This '--null-oid' thing makes me wonder exactly what it does. Yours gives a type-less object back, but what about scripts that want the OID of the empty blob or tree?

Would having something like '--null-oid[=<type>]' be useful for them? On the one hand, it seems like a thing that would be useful, but on the other, those aren't *the* null OID when 'type' is 'blob' or 'tree'. A more appropriate name in that case might be '--empty-oid=tree'.

So, that's an argument that '--null-oid' and '--empty-oid[=<type>]' should be two distinct things. I think I like that best. Do you have any thoughts about it?

Thanks, Taylor