Re: PATCH: improve git switch documentation

[Matt Rogers <mattr94@gmail.com>]

On Wed, Jun 30, 2021 at 4:50 AM Martin <git@mfriebe.de> wrote:
>
> On 30/06/2021 00:39, Junio C Hamano wrote:
> > Martin <git@mfriebe.de> writes:
> >
> >> My text may indeed have lacked clarity. I was trying to emphasize to
> >> hard, that this
> >> command's "force" enables 2 actions that may both not be
> >> wanted. Usually if one applies
> >> "force" to a command only one such action is expected, or at least I
> >> would only expect the one.
> > Oh, I do agree wholeheartedly if two things are forced at the same
> > time, things can become confusing.
> >
> > But the thing is, there are no such "two things are forced at once"
> > in this case.  That is why I emphasized, in my response to you, that
> > "switch -C <newbranch>" does not touch working tree, so "ok, the
> > switch stops because it requires some working tree files with
> > changes clobbered, and I can force it to make it happen" is not
> > involved.  If it were, then it becomes fuzzy if --force is allowing
> > an existing branch getting overwritten, or allowing a modification
> > in a working tree file getting discarded, or both.
> Well, yes and no. IMHO.
>
>  From what I have seen, there are main 2 cases people use -C.
>
> 1) By accident, meaning to do something else. Most often meaning to do a
> rebase.
> I.e. some one who is new, desperately to fix "branch has diverged".
> For this, those people need to be made aware that -C does not move the
> commits.
>
> 2) Intentional, when the branch to be re-created points to a commit,
> which is hold
>   by further branches. So no commit becomes unreachable.
> In that case it is not a documentation issue. It is a, how can I enable
> the re-create,
> but have git warn me, if I somehow misjudged the situation and on other
> branch
> has the commit. That is, when I see this as 2 individually actions, out
> of which I want
> to allow only one. Anyway that is not documentation, and I did sent
> another mail.
>

I just want to point out that my usual use-case for using -C (or checkout -f,
but the usage is similar enough for this discussion) is when I want to create
a temporary branch with a generic name (e.g. tmp) and I haven't cleaned
out my unused branches in a while.  If I find myself having branched off the
wrong commit and wanting to move work I already committed, the user should
be looking to use either rebase or merge for that.

I would also consider that using a command literally called "switch
--force-create"
does not seem like the obvious first choice for "My history is
different than that
history".



> And yes, for the documentation, it *should* be clear that, removing a
> branch, removes the
> commits on it.
> But then it must be said, that the branch is first removed. That is not
> currently the case.
> I proposed an alternate text to that nature in my last mail.
>
> For the rest, it is a matter of opinion.
> When I think a new user may read this, I believe such consequential
> implications should
> be mention rather explicit.
> But, if your view (the view of the git team is) a new user should have
> read up far enough
> to be fully aware of those consequence, then so be it.
>
> As per my previous mail, then maybe
>        Force creating a branch, means that an existing branch of the
> same name is removed.
>       A new branch is created at the specified <start point>. The
> new branch will not
>       necessarily have all the commits that the existing branch used to
> have.
>

I think the current documentations usage of "reset" in

    Similar to --create except that if <new-branch> already exists, it
will be reset to <start-point>.

Is pretty clear about what happens, although it does rely on users
being familiar
with the semantics of "resetting" a la git reset.  I think rephrasing
it in terms of
branch removal/creation actually obfuscates the matter.


> Well, if one creates a new feature branch, and instead of forking of
> master, one forks of some
> random other branch. Then one can immediately re-create it at the
> original intended
> branch point. No commits on the branch, none lost.
> But teach that to a newbie, and they may have committed to the branch,
> before they
> realize they forked at the wrong point. If the then do -C those commit
> will be gone. (well, yes the reflog).
>

I don't think that this is a great usage of switch -C.  generally I teach people
to look at the state of their repository via `git log --graph
--oneline --all` and then
decide whether they need to rebase their work or if they can just reset onto the
branch they want to.


-- 
Matthew Rogers