Re: [PATCH/RFC] WIP: log: allow "-" as a short-hand for "previous branch"

[Siddharth Kannan <kannan.siddharth12@gmail.com>]

Hello Matthieu,

On 8 February 2017 at 20:10, Matthieu Moy <Matthieu.Moy@grenoble-inp.fr> wrote:
> In a previous discussion, I made an analogy with "cd -" (which is the
> source of inspiration of this shorthand AFAIK): "-" did not magically
> become "the last visited directory" for all Unix commands, just for
> "cd". And in this case, I'm happy with it. For example, I never need
> "mkdir -", and I'm happy I can't "rm -fr -" by mistake.
>
> So, it's debatable whether it's a good thing to have all commands
> support "-". For example, forcing users to explicitly type "git branch
> -d @{1}" and not providing them with a shortcut might be a good thing.

builtin/branch.c does not call setup_revisions and remains unaffected
by this patch :)

In my original patch post, I was not explicit about what files call
setup_revisions.
I would like to rectify that with this (grep-ed) list:

* builtin/blame.c
* builtin/diff.c
* builtin/diff-files.c
* builtin/diff-index.c
* builtin/diff-tree.c
* builtin/log.c
* builtin/rev-list.c
* builtin/shortlog.c
* builtin/fast-export.c
* builtin/fmt-merge-msg.c
builtin/add.c
builtin/checkout.c
builtin/commit.c
builtin/merge.c
builtin/pack-objects.c
builtin/revert.c

* marked commands only show information, and don't change anything.

As you might notice, in this list, most commands are not of the `rm` variety,
i.e. something that would delete stuff.

In the next version of this patch, I will definitely include the list
of commands
which are "rm-ish" and affected by this patch.

>
> I don't have strong opinion on this: I tend to favor consistency and
> supporting "-" everywhere goes in this direction, but I think the
> downsides should be considered too. A large part of the exercice here is
> to write a good commit message!

Yes, I prefer consistency very much as well! Having "-" mean the same thing
across a lot of commands is better than having that shorthand only in a few
commands, as it is now. Unless there is a specific confusion that might arise
because of this shorthand inclusion, I think that this shorthand
should be supported
across the board.
(I especially like typing `git checkout - <filename>` which is very handy!)

>
> Another issue with this is: - is also a common way to say "use stdin
> instead of a file", so before enabling - for "previous branch", we need
> to make sure it does not introduce any ambiguity. Git does not seem to
> use "- for stdin" much (most commands able to read from stdin have an
> explicit --stdin option for that), a quick grep in the docs shows only
> "git blame --contents -" which is OK because a revision wouldn't make
> sense here anyway.

Yes, just to jog your memory, this was discussed here [1]

Junio said:

    As long as the addition is carefully prepared so that we know it
    will not conflict (or be confused by users) with possible other uses
    of "-", I do not think we would mind "git branch -D -" and other
    commands to learn "-" as a synonym for @{-1}.

>
> --
> Matthieu Moy
> http://www-verimag.imag.fr/~moy/

Thanks a lot for the review on this patch, Matthieu!

-- 

Best Regards,

- Siddharth.

[1]: https://public-inbox.org/git/7vmwpitb6k.fsf@alter.siamese.dyndns.org/