Re: Proposal/Discussion: Turning parts of Git into libraries

>
> On Thursday, March 23, 2023 7:22 PM, Felipe Contreras wrote:
> >On Sat, Feb 18, 2023 at 5:12 AM Phillip Wood <phillip.wood123@gmail.com> wrote:
> >>
> >> On 18/02/2023 01:59, demerphq wrote:
> >> > On Sat, 18 Feb 2023 at 00:24, Junio C Hamano <gitster@pobox.com> wrote:
> >> >>
> >> >> Emily Shaffer <nasamuffin@google.com> writes:
> >> >>
> >> >>> Basically, if this effort turns out not to be fruitful as a whole,
> >> >>> I'd like for us to still have left a positive impact on the codebase.
> >> >>> ...
> >> >>> So what's next? Naturally, I'm looking forward to a spirited
> >> >>> discussion about this topic - I'd like to know which concerns
> >> >>> haven't been addressed and figure out whether we can find a way
> >> >>> around them, and generally build awareness of this effort with the community.
> >> >>
> >> >> On of the gravest concerns is that the devil is in the details.
> >> >>
> >> >> For example, "die() is inconvenient to callers, let's propagate
> >> >> errors up the callchain" is an easy thing to say, but it would take
> >> >> much more than "let's propagate errors up" to libify something like
> >> >> check_connected() to do the same thing without spawning a separate
> >> >> process that is expected to exit with failure.
> >> >
> >> >
> >> > What does "propagate errors up the callchain" mean?  One
> >> > interpretation I can think of seems quite horrible, but another
> >> > seems quite doable and reasonable and likely not even very invasive
> >> > of the existing code:
> >> >
> >> > You can use setjmp/longjmp to implement a form of "try", so that
> >> > errors dont have to be *explicitly* returned *in* the call chain.
> >> > And you could probably do so without changing very much of the
> >> > existing code at all, and maintain a high level of conceptual
> >> > alignment with the current code strategy.
> >>
> >> Using setjmp/longjmp is an interesting suggestion, I think lua does
> >> something similar to what you describe for perl. However I think both
> >> of those use a allocator with garbage collection. I worry that using
> >> longjmp in git would be more invasive (or result in more memory leaks)
> >> as we'd need to to guard each allocation with some code to clean it up
> >> and then propagate the error. That means we're back to manually
> >> propagating errors up the call chain in many cases.
> >
> >We could just use talloc [1].
>
> talloc is not portable.