Re: master^ is not a local branch -- huh?!?

[Michael Witten <mfwitten@gmail.com>]

On Fri, Jan 29, 2010 at 4:12 PM, Ron Garret <ron1@flownet.com> wrote:
> In article <7vmxzwh906.fsf@alter.siamese.dyndns.org>,
>  Junio C Hamano <gitster@pobox.com> wrote:
>
>> Sverre Rabbelier <srabbelier@gmail.com> writes:
>>
>> > On Fri, Jan 29, 2010 at 22:24, Ron Garret <ron1@flownet.com> wrote:
>> >> Yes, I read that.  But what I'm trying to do is not just *look* at the
>> >> history, I want to restore my working tree to a previous version.  The
>> >> "Exploring History" section of the docs doesn't say how to do that.
>> >
>> > Do you want to restore your working tree only, or also throw away the
>> > history? If the former, you could look at 'git revert',...
>>
>> I think he wanted to check paths out of a commit and the set of paths
>> happened to be "everything".
>>
>> IOW, "checkout $commit ."
>
> Yes!!!  That's it exactly!

However, that updates the index and doesn't delete files that didn't
exist in $commit, and you said earlier that you don't want to update
the index (though perhaps you didn't really know what you wanted
there).

My idea:

Isn't the difference between 'checkout' and 'reset' almost essentially
a matter of whether the branch reference (HEAD), index, and tree are
modified? Couldn't these commands be merged into one command or make
use of one command?

Rather than relying on flags like --hard, --soft, and --mixed, why not
*also* provide flags for specifying at a finer granularity what is
desired for the index, working tree, and HEAD.

Then:
    git checkout $commit
does a lot of its work through something like:
    git update --index --tree --detach $commit

Also:
    git checkout $commit $f
translates:
    git update --index --tree --keep-tracked-files $commit $f

Also:
    git reset [--mixed] $commit
translates:
    git update --index --head $commit

Also:
    git reset --soft $commit
translates:
    git update --head $commit

Also:
    git reset --hard $commit
translates:
    git update --index --tree --head $commit

And so on.

In fact, with --no-* flags, you could modify 'reset' and 'checkout'
commands from their defaults. So, to update all of the paths
(including deleting tracked files not in $commit), but keep the index
untouched, we have:

    git checkout --no-update-index --no-update-keep-files $commit .

Of course, you might as well just use the hypothetical 'update'
command directly:

    git update --tree $commit .

Sincerely,
Michael Witten