Re: [PATCH/RFC] builtin-checkout: suggest creating local branch when appropriate to do so

[Jay Soffian <jaysoffian@gmail.com>]

On Tue, Oct 13, 2009 at 11:28 PM, Junio C Hamano <gitster@pobox.com> wrote:
> When you do not have local "frotz" branch, and do have cloned/fetched from
> the origin that has "frotz" branch, I am actually Ok with this
>
>    $ git checkout frotz [--]
>
> to do an equivalent of:
>
>    $ git checkout -t -b frotz origin/frotz
>
> I do not have problem with this _particular_ DWIMmery.  It will not break
> people's expectations, other than "asking to check out non-existing ref
> should fail".  That expectation might be logical, but I do not think it is
> useful.
>
> Another reason I won't have problem with this one is that perhaps after
> creating a few more commits, the next day when the user does the same
>
>    $ git checkout frotz
>
> what will be shown is the _local_ frotz branch.  Nowhere in this sequence
> there is any room to mistake that you somehow checked out a branch owned
> by somebody else (namely, origin).  You started by auto-creating your
> local branch, worked on it, and checked it out again the next day.  In
> other words, this is really about a shorthand to create a new local branch
> called "frotz" when the commit that the branch should start from is
> clearly unambiguous.

Okay, this is good, and I can work up a patch if no one beats me to the punch.

> I have trouble with yours, on the other hand, which is to make
>
>    $ git checkout origin/frotz
>    $ git checkout v1.5.5
>
> into
>
>    $ git checkout -b frotz-47 origin/frotz
>    $ git checkout -b v1.5.5-47 v1.5.5

I suggested no such thing, at least, I don't think I did. What I said was:

---snip---
Modify checkout so that the first commit while detached automatically
creates a branch. Perhaps the name is derived from the branch point,
or the user is prompted for a name.
---snip---

So we'd only automatically create a new branch at commit time. But
never mind that, it was just a suggestion and I don't like it.

What if instead we do something like this:

$ git checkout v1.5.5
Note: moving to 'v1.5.5' which isn't a local branch
If you want to create a new branch from this checkout, you may do so
(now or later) by using -b with the checkout command again. Example:
  git checkout -b <new_branch_name>
HEAD is now at 1d2375d... GIT 1.5.5
$ [edit foo.c]
$ git add foo.c
$ git commit -m "edited some file"
Cannot commit to v1.5.5. Please use git commit -b <branch> to specify
the name of a new branch to commit to, or use git commit --detach to
force a detached commit.

So we modify git to, by default, no longer allow creating a commit
while detached or on a branch that cannot be committed to.

j.