On Tue, Apr 30, 2013 at 12:22 PM, Junio C Hamano <gitster@xxxxxxxxx> wrote:
> Duy Nguyen <pclouds@xxxxxxxxx> writes:
>
>> On Tue, Apr 30, 2013 at 2:35 AM, Felipe Contreras
>> <felipe.contreras@xxxxxxxxx> wrote:
>>> So we can type '@' instead of 'HEAD@', or rather 'HEAD'. So now we can
>>> use 'git show @~1', and all that goody goodness.
>>
>> I like this. I haven't spent a lot of time on thinking about
>> ambiguation. But I think we're safe there. '@' is not overloaded much
>> like ':', '^' or '~'.
>>
>>> This patch allows 'HEAD@' to be the same as 'HEAD@{0}', and similarly with
>>> 'master@'.
>>
>> I'm a bit reluctant to this. It looks like incomplete syntax to me as
>> '@' has always been followed by '{'. Can we have the lone '@' candy
>> but reject master@ and HEAD@? There's no actual gain in writing
>> master@ vs master@{0}.
>
> Originally I was going to say the same, but after thinking about it
> a bit more, I changed my mind.
>
> If you accept only "@" but not "master@", that behaviour needs a
> wrong world model to understand and justify (one of which is "@ is a
> synonym for HEAD"). If your rule is "In $anything@{$n}, you can
> drop {$n} when $n==0", then HEAD@{0} becomes HEAD@ and master@{0}
> becomes master@, and @{0} becomes @ naturally.
>
> We should make sure that the code rejects "git update-ref @ foo"
> because that is "git update-ref @{0} ref", by the way. I didn't
> check with Felipe's patch.
Hmm, with or without my patch 'git update @ foo' does nothing, same
with 'git update blah foo'. No error, no non-zero exit code, just
doesn't do anything.
>>> +'@'::
>>> + '@' alone is a shortcut for 'HEAD'
>>> +
>
> I think this explanation sends a wrong message, hinting as if you
> can expect "update-ref @ master", "symbolic-ref @ refs/heads/next"
> etc. to do something sensible to HEAD.
Why would it? This is Documentation/revisions.txt, 'update-ref' has
nothing to do with that.
This hints that the user can do "update-ref @" as much as the
paragraph below thins that that user can do "update-ref
master@{today}".
Cheers.
--
Felipe Contreras
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