Re: Submodule regression in 2.14?

From: Stefan Beller <sbeller@google.com>
Date: Aug 22, 2017, 18:10 UTC
Message-ID: <CAGZ79kbwJN_XVcAbkyVJTax9F2NR4EO8XjR3U9EH8MLqbAb90Q@mail.gmail.com>
In-Reply-To: <20170822153311.GA5697@book.hvoigt.net>

On Tue, Aug 22, 2017 at 8:33 AM, Heiko Voigt <hvoigt@hvoigt.net> wrote:

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> On Mon, Aug 21, 2017 at 09:42:54AM -0700, Stefan Beller wrote:
>> On Mon, Aug 21, 2017 at 9:05 AM, Heiko Voigt <hvoigt@hvoigt.net> wrote:
>> > On Fri, Aug 18, 2017 at 11:51:13PM -0700, Junio C Hamano wrote:
>> >> As long as we are talking about idealized future world (well, at
>> >> least an idea of somebody's "ideal", not necessarily shared by
>> >> everybody), I wonder if there is even any need to have commits in
>> >> submodules in such a world.  To realize such a "monorepo" world, you
>> >> might be better off allowing a gitlink in the superproject to
>> >> directly point at a tree object in a submodule repository (making
>> >> them physically a single repository is an optional implementation
>> >> detail I choose to ignore in this discussion).
>> >
>> > IMO this is one step to far. One main use of submodules are shared
>> > repositories that are used by many superprojects. The reason you want to
>> > have commits in the submodule are so that you can push them
>> > independently and all other users can pick up the changes. You could get
>> > by by Using the superproject commits for the submodule once you push or
>> > something but those do not necessarily make sense in the context of the
>> > submodule.
>> >
>> > So I think it is important that there are commits in the submodule so
>> > its history makes sense independently for others.
>> >
>> > Or how would you push out the history in the submodule in your idea?
>> > Maybe I am missing something? What would be your use case with gitlinks
>> > pointing to trees?
>>
>> Well there are still commits, but in the superproject the UX feels more
>> as if the submodules were special trees.
>
> Ah ok then I misunderstood. So they only feel like trees.
>
>> So if you want to interact with
>> the submodule specifically, you could do things like
>>
>>     git add /path/inside/sub
>>     # works seamlessly from the superproject tree
>
> Would that mean that we need to loosen/keep the requirement loose for a
> name from .gitmodules? I am asking because of my series for on-demand
> fetch of renamed submodules. For the full functionality I would require
> a name.
>
> Would that be in a scenario where the user would then e.g. push the
> submodule into the superproject?
>
> Ah wait I misunderstood again. You mean a file in an existing
> submodule right? Not adding submodule from a repository a user moved
> there?

Assuming the submodule is at /path in this example, the effect of that command could be achieved today via

    git -C /path add inside/sub

(i.e. for git-add we "just" detect that there is a submodule boundary and run the git-add inside the submodule)

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>
>>     git commit --submodule-commit-only
>>     # When the flag is not give, you may get an editor
>>     # asking for two commit messages, (sub+super)
>
> Or maybe something like
>
>     git commit --submodule path/to/submodule

Yes. In todays UX, you do

    git -C path/to/submodule commit

for the command that you proposed. For a plain git-commit in the superproject, we could envision this sequence of todays commands:

    git -C submodule commit
    git add submodule
    git commit

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>
> so the user can specify which submodule she wants. I first wrote it
> without the switch but but that collides with listing files which should
> be added. IMO this shorter option is also more intuitive to understand
> what it does (for this case).
>
>>     git fetch --submodule
>>     # When the flag is not given, we'd fetch superproject and
>>     # on-demand
>
> Yes like above we should add the path to the submodule right?

yes.

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>
>>     # You feel the superproject is in the way?
>>     git worktree add --for-submodule <path/to/sub> ...
>>     # The new submodule worktree puts the
>>     # submodule only UX first. so it feels like its own
>>     # repository, no need for specific flags.
>
> I am not sure I understand this one. What would that do? Put a worktree
> for submodule path/to/sub to ...?

Yes, and at "..." you would have the UX of the submodule being its own repository, no interaction with the superproject.

>
> Overall I like the direction of these ideas.
>
> Cheers Heiko