Re: swh-plugins-lv2: New variable [WIP] v2

[Leo Famulari <leo@famulari.name>]

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. ;)

> 
> Thanks,
> Ludo’.
>