Re: Pack files, standards compliance, and efficiency

[Jeff King <peff@peff.net>]

On Fri, Jun 05, 2015 at 05:14:25PM +0700, Duy Nguyen wrote:

> I'm more concerned about breaking object_id abstraction than C
> standard. Let's think a bit about future. I suppose we need to support
> both sha-1 and sha-512, at least at the source code level.

I think that's going to be a much bigger issue, because we are casting
out of a defined, on-disk data structure here. So I'd rather defer any
code changes around this until we see what the new data structure (and
the new code) look like.

> That might make casting tricky. Maybe we should deal with it now
> instead of delaying because if the final solution is vastly different,
> we may be redoing this conversion again. In any case, if we cast, we
> should make it grep-able (maybe hide the casting in a macro so we can
> grep the macro's name) so we can examine them when the time comes for
> us to move away from sha-1.

I think that is sensible. Something like:

  #define SHA1_TO_OBJID(sha1) ((struct object_id *)sha1)

would probably be a good start.

-Peff