From mboxrd@z Thu Jan  1 00:00:00 1970
From: ludo@gnu.org (Ludovic =?utf-8?Q?Court=C3=A8s?=)
Subject: Re: swh-plugins-lv2: New variable [WIP] v2
Date: Tue, 08 Dec 2015 09:52:30 +0100
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In-Reply-To: <87r3ixzifw.fsf@netris.org> (Mark H. Weaver's message of "Mon, 07
	Dec 2015 23:13:23 -0500")
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To: Mark H Weaver <mhw@netris.org>
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Mark H Weaver <mhw@netris.org> skribis:

> Ricardo Wurmus <rekado@elephly.net> writes:
>
>>> +(define-public swh-plugins-lv2
>>> +  (let ((commit "5098e09e255eaed14e0d40ca5e7e6dfcb782d7ea"))
>>
>> We usually don=E2=80=99t use full commit hashes.  You could probably tri=
m it to
>> the first six characters or so.
>
> I would recommend using at least 10 characters, maybe more.  We should
> use enough characters to ensure that the commit id remains unique for as
> long as this package version remains in use -- keeping in mind that for
> purposes of reproducing old experiments, someone might try to build this
> package+version several years from now.

I sympathize with this.  I would think 10 digits is more than needed,
though: With 6 hex digits, it takes on average 16^6 =3D 16M commits before
the 6-digit ID is ambiguous, and with 8 hex digits that goes to
4=C2=A0billion commits (Emacs has around 123,000 commits as an example.)

But anyway, to be super-safe, we could use the full SHA1 in the URL, but
strip it in the =E2=80=98version=E2=80=99 field so that it remains readable.

Thoughts?

Thanks,
Ludo=E2=80=99.