Re: [PATCH] builtin/worktree.c: add option for setting worktree name

From: Junio C Hamano <gitster@pobox.com>
Date: Jun 25, 2016, 19:45 UTC
Message-ID: <xmqq1t3ldpdl.fsf@gitster.mtv.corp.google.com>
In-Reply-To: <1FEF5F90-6534-4D91-B27C-16FE6D16EC3F@brennie.ca>

Barret Rennie <barret@brennie.ca> writes:

Show 26 quoted lines

>> What is "the name for the worktree"? Is it the directory where it lives in?
>>Is it how it is listed with 'git worktree list'?
>
> The name of the worktree is the name of the created directory in
> `.git/worktrees`.
>
>> How is --name different from the <path> argument?
>
> Currently, if you run:
> 	
> 	git worktree add /my/worktree/checkout <branch>
>
> you get a worktree "named" checkout, i.e., `.git/worktrees/checkout`. The
> idea with this patch is to allow you use a more specific name when you would
> otherwise have mulitiple worktrees of the form `checkout`, `checkout1`, etc.
>
> That is, you could do
>
> 	git worktree add --name branch1 /worktrees/branch1/src branch1
> 	git worktree add --name branch2 /worktrees/branch2/src branch2
> 	git worktree add --name branch3 /worktrees/branch3/src branch3
>
> and have `.git/worktrees/branch1`, `.git/worktrees/branch2` and
> `.git/worktrees/branch3` instead of `.git/worktrees/src`,
> `.git/worktrees/src1`, `.git/worktrees/src2`. That way, it becomes more clear
> when poking inside `.git/worktrees` which directory points to which checkout.

That is a way better justification of "why we need to use a custom name, not the default one" than the previous "with this we can use a custom name".

As long as you can justify why having anything underneath branch$n/ is necessary, that is. In your explanation above, it is still unclear why you need a checkout at /worktrees/branch$n/src/, and why it would not work if it is at /worktrees/branch$n/.

Note that I am not saying "there cannot be a good reason, do not add this feature" when I say "it is unclear why". I am encouraging you and others in this discussion thread to find good use cases for the proposed new feature and come up with materials to help improving the documentation part of the patch. That way, the users with similar needs can find how the feature is supposed to be used and understand the feature better.

I suspect that this new feature might be useful when two more more interdependent projects (they could be organized as submodules in a superproject, but they can be independent checkouts of different projects) are used together. Imagine frotz and nitfol projects, and without fancier setup to have multiple checkouts, you may be expected (by these two projects) to check them out like so:

    $top/frotz/
    $top/libs/nitfol/

where $top can be anywhere but to clarify the line of thought, lets pick a concrete place, say $HOME/xyzzy. So without worktrees, you would have

    $HOME/xyzzy/frotz
    $HOME/xyzzy/libs/nitfol

Now, if you do the worktree, you may still want the relative structure between these two, i.e. if you want to work on two different branch combinations of the whole thing, you would want to do this:

    $HOME/xyzzy-1/frotz       - borrow from $HOME/xyzzy/frotz
    $HOME/xyzzy-1/libs/nitfol - likewise for nitfol

    $HOME/xyzzy-2/frotz       - borrow from $HOME/xyzzy/frotz
    $HOME/xyzzy-2/libs/nitfol - likewise for nitfol

where xyzzy-$n may be for topic-$n branch both in frotz and nitfol.

And explained that way, it becomes clearer that you would want to name $HOME/xyzzy-1/frotz worktree after "topic-1", not the default name you would get "frotz" (because the default gives you the leaf level name of the newly created worktree).

After the discussion above (which may or may not match what you raised this topic for), I think a feature to let you override the default name makes sense.

It just needs to be explained better to help the users when the feature eventually becomes part of Git. Also, others (especially Duy) may have even better ideas (e.g. instead of having to always use --name to give custom name for all worktrees, set a "hint" just once to help the logic that comes up with the default name give a better name), so while the feature may be desirable, your exact implementation may or may not be what we eventually want to adopt.

Thanks.