Re: [PATCH] refspec: make @ a valid refspec

[Felipe Contreras <felipe.contreras@gmail.com>]

On Tue, Nov 24, 2020 at 5:47 PM Jacob Keller <jacob.keller@gmail.com> wrote:
>
> On Tue, Nov 24, 2020 at 3:14 PM Junio C Hamano <gitster@pobox.com> wrote:
> >
> > Jacob Keller <jacob.keller@gmail.com> writes:
> >
> > >> Worse yet, @{4} does not refer to HEAD@{4} but refers to the 4-th
> > >> previous commit the current branch pointed at, so a mnemonic for the
> > >> end user to remember the distinction between the two is that a bare
> > >> "@" is different from HEAD, which is a total opposite X-<.
> > >>
> > >
> > > However, @{0} *does* refer to what is currently checked out, which
> > > would be head.. So in a sense @ meaning "the current branch" and
> > > applying @{0} would always be HEAD, no?
> >
> > Not really.
> >
> > It happens to hold true for @{0}, because by definition you couldn't
> > have been on a different branch than the current one when you made
> > the topmost commit on the current branch.  For @{1} and higher, it
> > is always "where was the current branch at N commits ago?" which is
> > different from "where was the HEAD at N commits ago?", unless you
> > always use a single branch and never switch away.
>
> Right, once you add anything greater than zero it breaks down.. but
> think about it a little differently: "@{N}" is sort of eliding the
> branch name, which means we use the current branch. "branch@" (if it
> were valid syntax) would be eliding the number which means "the most
> recent version of branch". Thus, eliding both and using just "@" would
> mean "the most recent version of the current branch", which cannot be
> anything other than HEAD.

Yes, but to me HEAD is supposed to mean "the current branch", so
"branch@{1}" and "HEAD@{1}" should be the same, and they are not. So
to me they are the other way around.

1. branch@{1}, HEAD@{1}, @@{1}: current branch 1 commit ago
2. @{1}: 1 commit ago in general

Since it's the opposite of what I would expect, I simply don't use
these notations.

-- 
Felipe Contreras