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

[ludo@gnu.org (Ludovic Courtès)]

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.)

Ludo’.