Re: [PATCH] do not pass "repo" to builtin commmand implementations

[Junio C Hamano <gitster@pobox.com>]

"Hardik Kumar" <hardikxk@gmail.com> writes:

> This would certainly help make it more obvious as not use the pointer
> parameter. But would you not consider to eventually move towards
> something more efiicient in the future?

It is unclear what kind of more efficient alternative you have in
mind.

The primary motivation for this change is to make the implementation
of built-in commands less error-prone and harder to abuse.  The
implementation of 'git foo' in cmd_foo() in builtin/foo.c performs
one-time initialization (such as calling git_config()) and
finalization that cannot be repeated, making it an anti-pattern to
call cmd_foo() from within cmd_bar().  Refraining from pretending
these functions can operate on an arbitrary caller-supplied
repository instance is one step toward preventing such misuse.

However, another motivation for this change is to encourage
developers who want to aid the libification effort to refactor code
out of cmd_foo() into reusable helper functions.  Instead of keeping
those helpers within builtin/foo.c, they can be moved to library
files outside the builtin/ directory and take a pointer to 'struct
repository'.

The top-level cmd_foo() can still access 'the_repository' directly
and orchestrate the execution of 'git foo' by passing a pointer to
these helper functions.  That way, more code becomes reusable.