Re: [PATCH] diff: allow --recurse-submodules as an synonym for --submodule

[Jonathan Nieder <jrnieder@gmail.com>]

Junio C Hamano wrote:
> Jonathan Nieder <jrnieder@gmail.com> writes:

>> It seems like various commands are gaining --recurse-submodules options
>> taking different kinds of arguments:
>>
>> - clone takes --recurse-submodules=<pathspec>
>> - fetch takes --recurse-submodules=<mode>
>> - after this patch, diff takes --recurse-submodules=<mode>
>>
>> Is there a unifying principle?  Can Documentation/gitsubmodules.txt
>> say a word or two about what kind of argument values the user should
>> expect to be accepted by these options?
>
> I am not sure if the above is rhetorical.  The only thing such a
> document can say about status-quo is that the user cannot make an
> educated guess, as there is no consistency.  Some take an option to
> clarify which subset of submodules to act on, others take an option
> to specify what variant of operation to be made on the submodules.

It's not rhetorical: I really do want to find out what our plan is for
the future of --recurse-submodules.

One possibility (A) would be "accept pathspec everywhere", as you
mentioned.  For a command like fetch that already accepts <mode>, that
is problematic and would involve a migration.  If we already have to
migrate fetch, migrating diff as well does not seem too bad.

Another possibility (B) would be "accept pathspec in clone only".  A
clone is a bit of a special case in that it is setting up the set of
active submodules; perhaps we want other commands to always respect
that set of active submodules without a method for overriding and only
acting on a subset.  After all, "git checkout <branch>" doesn't have a
way to only checkout <branch> on a subset of the worktree; why should
"git checkout --recurse-submodules <branch>" be any different?

When I think about it this way, I suspect that (B) will provide a
better experience than (A), so this diff change doesn't seem like a
step in the wrong direction.  Except: it took me a long time to think
this through.  Some documentation really would help, since it would
mean that the next person can understand what the *intention* behind
these options are and save some time thinking through other not-chosen
alternatives.

Hmm?

Thanks,
Jonathan