Re: [PATCH v8 3/4] worktree add: add --orphan flag

From: Jacob Abel <jacobabel@nullpo.dev>
Date: Jan 18, 2023, 22:18 UTC
Message-ID: <20230118221745.wovefwx6vhcm3zzk@phi>
In-Reply-To: <xmqqo7r0ijdv.fsf@gitster.g>

On 23/01/14 07:09PM, Junio C Hamano wrote:

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> Jacob Abel <jacobabel@nullpo.dev> writes:
>
> >> 	git worktree add --orphan -b topic main
> >> 	git worktree add --orphan -B topic main
> >
> > I am hesitant to add these as they break away from the syntax used in
> > `git switch` and `git checkout`.
>
> Not that I care too deeply, but doesn't it introduce end-user
> confusion if we try to be compatible with "git checkout --orphan
> <branch>", while allowing this to be compatible with the default
> choice of the branch name done by "git worktree add"?  "--orphan" in
> "git checkout" behaves similar to "-b|-B" in that it always wants a
> name, but "git worktree add" wants to make it optional.

Yes. I think it's a fairly minor degree of confusion but I agree that it adds potentially unneeded confusion.

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>
> By the way "--orphan" in checkout|switch wants to take a name for
> itself, e.g.
>
> 	git checkout --orphan $name [$commit]
> 	git checkout -b $name [$commit]
> 	git checkout -B $name [$commit]
>
> so it is impossible to force their "--orphan" to rename an existing
> branch, which is probalby a design mistake we may want to fix.

Can you elaborate on what you mean by "rename an existing branch" here?

Do you mean like `git checkout --orphan $branchname` being able to convert an existing branch into an orphan/unborn branch?

Also a small point but in an earlier thread [1], we made the decision to model functionality on `git switch --orphan $branch` instead of `git checkout --orphan $branch [$commit]`.

>
> In any case, as I said, I do not care too deeply which way you guys
> decide to go, because I think the whole "orphan" UI is a design
> mistake that instills a broken mental model to its users [*].

Understood.

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>
> But let's wait a bit more to see which among
>
> (1) git worktree add [[--orphan] -b $branch] $path
>     This allows --orphan to act as a modifier to existing -b,
>
> (2) git worktree add [(--orphan|-b) $branch] $path
>     This allows --orphan to be another mode of -b, or
>
> (3) git worktree add [--orphan [$branch]|(-b $branch)] $path
>     This allows --orphan to default to $(basename $path)
>
> people prefer.
>

I'd personally argue that option 2 (the current behavior) is probably the cleanest path forward as option 3 requires a bit of awkward code [2] and `--orphan` is such an esoteric option that the user may only use it once or twice in the life of a given repository, if that.

And eventually I'd like `git worktree add $path` to "just work" on a new/empty repository. However as things stand, there wasn't an easy way to do this without leading to potentially confusing behavior. It can be done, I just haven't taken the time to figure it out yet.

Once `git worktree add $path` "just works" (when creating the first branch in a repo), I highly doubt anyone would use `--orphan` often enough to justify the use of shorthand options 1 or 3.

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>
> [Footnote]
>
> * I am not saying that it is wrong or useless to keep an unrelated
>   history, especially one that records trees that have no relevance
>   to the main history like created with "switch --orphan", in the
>   same repository.  Allowing "git switch --orphan" to create such a
>   separate history in the same repository blurs the distinction.  It
>   would help newbies to form the right mental model if they start a
>   separate repository that the separate history originates in, and
>   pull from it to bootstrap the unrelated history in the local
>   repository.

Definitely agreed that `--orphan` is esoteric and probably should be avoided by most users where possible.

1. https://lore.kernel.org/git/CAPig+cSVzewXpk+eDSC-W-+Q8X_7ikZXXeSQbmpHBcdLCU5svw@mail.gmail.com/
2. https://lore.kernel.org/git/20230114224956.24801-1-jacobabel@nullpo.dev/