On Mon, 16 Apr 2018 14:22:35 -0700
Stefan Beller [off-list ref] wrote:

On Mon, Apr 16, 2018 at 9:37 AM, Antonio Ospite [off-list ref] wrote:

quoted

On Thu, 12 Apr 2018 16:50:03 -0700
Stefan Beller [off-list ref] wrote:

quoted

Hi Antonio,

On Thu, Apr 12, 2018 at 3:20 PM, Antonio Ospite [off-list ref] wrote:

quoted

When multiple repositories with detached work-trees take turns using the
same directory as their work-tree, and more than one of them want to use
submodules, there will be conflicts about the '.gitmodules' file.

unlike other files which would not conflict?
There might be file names such as LICENSE, Readme.md etc,
which are common enough that they would produce conflicts as well?
I find this argument on its own rather weak. ("Just delete everything in
the working dir before using it with another repository"). I might be
missing a crucial bit here?

All the vcsh repositories _share_ the same work-tree; they may control
it taking turns but, in general, all files are meant to be checked out
at all times as the basic use case is: *distinct* sets of config files.

Maybe saying that the repositories "take turns" is confusing.
It's an unnecessary information, so I will omit that part form the
commit message.

So they all have the same workdir, do they track the same set of files
or do they track a disjoint set of files, and ignoring the other repositories
files via the ignore mechanism?

To recap,

vcsh[1] sets $HOME as the work-tree of multiple repositories to track
different sets of dotfiles in distinct repositories, while still having
the files directly available in $HOME. Each repository can ignore
untracked files via the ignore mechanism (namely core.excludesFile).

[1] https://github.com/RichiH/vcsh

For all this to work well, the sets of the tracked files would also need
to be disjoint, and usually they "practically" are, once a few
exceptions are taken care of.

Common intersecting items like LICENSE and README can be handled via
sparse-checkout to have "disjoint checkouts" and this solves most of
the problems, but the same mechanism cannot be used for .gitmodules as
it needs to be checked out.

And the problem cannot be worked around like done with .gitignore
(using core.excludesFile instead) because .gitmodules is unique and
hardcoded.

This sounds like an interesting setup. I never though of that as something
useful (in either configuration).

Give vcsh a try maybe.

[...]

quoted

However I guess that my point here is that the gitmodules file is
something that influences git behavior so it should not be on the user's
shoulder to manage conflicts for it, and most importantly it needs to
be checked out for git to access it, doesn't it?

Good point! I wonder if the cleaner solution would be to just
tell git to use HEAD:.gitmodules and not check out the file?
then you would not need to come up with a namespace for names
of the .gitmodules files and scatter them into the worktree as well?

Any solution which:

  1. prevents the gitmodules file to be checked out
  2. but still tracks it in the git repository

OR
  
  1. allows to set the gitmoudles file under some namespace

would work for vcsh I guess.

quoted

quoted

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-               value=$(git config -f .gitmodules submodule."$name"."$option")
+               gitmodules_file=$(git config core.submodulesfile)
+               : ${gitmodules_file:=.gitmodules}
+               value=$(git config -f "$gitmodules_file" submodule."$name"."$option")

I wonder if it would be cheaper to write a special config lookup now, e.g.
in builtin/submodule--helper.c we could have a "config-from-gitmodules"
subcommand that is looking up the modules file and then running the config
on that file.

Can you give an example from the user point of view of such a
"config-from-gitmodules" command?

    git submodule config <name> <option>

as an 'alias' for

               gitmodules_file=$(git config core.submodulesfile)
               : ${gitmodules_file:=.gitmodules}
               value=$(git config -f "$gitmodules_file"
submodule."$name"."$option")

The helper would figure out which config file to load form
(.gitmodules in tree, HEAD:.gitmodules, your new proposed gitmodules file,
.git/config... or the special ref) and then return the <option> for <name>

So maybe:

    $ git clone https://gerrit.googlesource.com/gerrit && cd gerrit
    # ^ My goto-repo with submodules

    $ git submodule config "plugins/hooks" URL
    ../plugins/hooks

I may look into such supporting changes once you decide the approach to
take for the bigger problem.

Thank you,
   Antonio

-- 
Antonio Ospite
https://ao2.it
https://twitter.com/ao2it

A: Because it messes up the order in which people normally read text.
   See http://en.wikipedia.org/wiki/Posting_style
Q: Why is top-posting such a bad thing?