Re: [GSoC][PATCH v5] submodule: port subcommand 'set-branch' from shell to C

[Shourya Shukla <shouryashukla.oo@gmail.com>]

On 03/06 01:02, Junio C Hamano wrote:
> I'd expect that when that day with no scripted parts of "git
> submodule" remains comes, the main entry point functions in
> builtin/submodule--helper.c (like module_list(), update_clone(),
> module_set_branch(), etc.) will become helper functions that live in
> submodule-lib.c and would be called from builtin/submodule.c.  And
> the conversion would rip out calls to parse_options() in each of
> these functions that would migrate to submodule-lib.c
> 
>     Side note: instead of adding submodule-lib.c, you could add them
>     directly to submodule.c if they are small enough.  I am however
>     modeling after how the "diff" family was converted to C; the
>     diff-lib.c layer is "library-ish helpers that get pre-parsed
>     command line arguments and performs a single unit of work" that
>     utilizes service routines at the lower layer that are in diff.c
>     and submodule-lib.c and submodule.c will be in a similar kind of
>     relationship.

There does exist a `submodule.c` outside of `builtin/` which has various
helper functions. Will that require renaming to `submodule-lib.c`? BTW
`set-branch` is a subcommand of `git submodule` so do we have to put it
into `submodule-lib.c` if there were to be one?
What is the motivation behind modelling it on the diff-family?