On Mon, Aug 8, 2022 at 6:06 PM Junio C Hamano <gitster@xxxxxxxxx
<mailto:gitster@xxxxxxxxx>> wrote:
>
> Johannes Schindelin <Johannes.Schindelin@xxxxxx
<mailto:Johannes.Schindelin@xxxxxx>> writes:
>
> > @@ -1420,6 +1420,12 @@ static int
interpret_nth_prior_checkout(struct repository *r,
> > const char *brace;
> > char *num_end;
> >
> > + if (namelen == 1 && *name == '-') {
> > + brace = name;
> > + nth = 1;
> > + goto find_nth_checkout;
> > + }
> > +
> > if (namelen < 4)
> > return -1;
> > if (name[0] != '@' || name[1] != '{' || name[2] != '-')
>
> If a solution along this line works, it would be far cleaner design
> than the various hacks we have done in the past, noticing "-" and
> replacing with "@{-1}". For one thing, we wouldn't be receiving a
> "-" from the end user on the command line and in response say @{-1}
> does not make sense in the context in an error message. That alone
> makes the above approach to deal with it at the lowest level quite
> attractive.
>
> In the list archive, however, you may be able to find a few past
> discussions on why this is not a good idea (some of which I may no
> longer agree with). One thing that still worries me a bit is that
> we often disambiguate the command line arguments by seeing "is this
> (still) a rev, or is this a file, or can it be interpreted as both?"
> and "-" is not judged to be a "rev", IIRC.
>
> Luckily, not many commands we have take "-" as if it were a file and
> make it read from the standard input stream, but if there were (or
> if we were to add a command to behave like so), treating "-" to mean
> the same thing as "@{-1}" everywhere may require the "does this look
> like a rev?" heuristics (which is used by the "earlier ones must be
> rev and not file, later ones must be file and cannot be interpreted
> as rev, for you to omit '--' from the command line" logic) to be
> taught that a lone "-" can be a rev.
>
> So it is quite a lot of thing that the new code needs to get right
> before getting there.
Agree. To make a substitution in the command line and to consider "-"
in interpret_nth_prior_checkout, I see them as two very different games.
Previous to this, I thought about making also a "git diff -",
https://github.com/gitgitgadget/git/pull/1314
<https://github.com/gitgitgadget/git/pull/1314>. Suddenly there was 5
commands with this substitution (checkout, merge, rebase, branch, diff)
so I follow a little the path now Johannes suggests, making the
substitution "- ~ @{-1}" deep in the system. For me, the implications,
error cases, test cases... to consider was not worth the change to
get what I was looking for: align the workflow "checkout/merge/branch
-d".
Also discarded the "git diff -" change, because of so many flags and
conditions "diff" has. So I only sent the "branch -" patch.
