Re: [PATCH v3 00/32] object-store: lookup_commit

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

Brandon Williams <bmwill@google.com> writes:

> I 100% think that we need to continue these refactorings with both the
> object store as well as with the_index (removing the index macros and
> removing the dependency on global state).  The whole compat macros most
> definitely was a failed experiment as we still haven't rid the code
> base of them yet.

These two are completely different things.  You can call the compat
macros a failed experiment only if two things hold true: (1) we want
to force all callsites to explicitly pass the_index even when they
always work on the primary in-core instance of istate and (2) they
were invented primarily in the hope that their presense will help us
achieve (1) sooner.  And neither is true.  The mechanism to allow
multiple in-core istate were of course helpful in places like branch
switching and merging, but we expected that the majority of
then-existing code would be required to work on the primary in-core
index, so s/foo_cache(/foo_index(&the_index/ conversion all over the
place were noisier than it was worth.  The compat macros were not
introduced as an experiment to help wean ourselves off of the
foo_cache API.  It was a total opposite---it was a consideration on
production code to help existing code keep working in backward
compatible way.  In short, they were neither failed nor experiment.

What you _could_ say about them, given that more code than before
would benefit by learning to work on istate instances other than the
default &the_index these days, is that they may have outlived their
usefulness, though.