From mboxrd@z Thu Jan  1 00:00:00 1970
From: Leo Famulari <leo@famulari.name>
Subject: Re: swh-plugins-lv2: New variable [WIP] v2
Date: Wed, 9 Dec 2015 16:24:43 -0500
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To: Ludovic =?iso-8859-1?Q?Court=E8s?= <ludo@gnu.org>
Cc: guix-devel@gnu.org

On Wed, Dec 09, 2015 at 09:56:37PM +0100, Ludovic Courtès wrote:
> Leo Famulari <leo@famulari.name> skribis:
> 
> > On Tue, Dec 08, 2015 at 09:52:30AM +0100, Ludovic Courtès wrote:
> >> Mark H Weaver <mhw@netris.org> skribis:
> >> 
> >> > Ricardo Wurmus <rekado@elephly.net> writes:
> >> >
> >> >>> +(define-public swh-plugins-lv2
> >> >>> +  (let ((commit "5098e09e255eaed14e0d40ca5e7e6dfcb782d7ea"))
> >> >>
> >> >> We usually don’t use full commit hashes.  You could probably trim 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 = 16M commits before
> >> the 6-digit ID is ambiguous, and with 8 hex digits that goes to
> >> 4 billion 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 ‘version’ field so that it remains readable.
> >> 
> >> Thoughts?
> >
> > I don't see a reason to not use the full hash. I know the odds but why
> > discard the information? We can't complain about it being ugly given the
> > aesthetics of /gnu/store. ;)
> 
> The ‘version’ field shows up in user interfaces, where aesthetics do
> matter IMO.  WDYT?
> 
> (In some cases, it’s also a good way to avoid hitting limitations on the
> shebang length and on the AF_UNIX socket name length.)

Okay, then I like your idea of using the full SHA1 in URLs but
truncating it in the 'version' field.

> 
> Ludo’.