Re: [PATCH 5/5] load_ref_decorations(): avoid parsing non-tag objects

[Jeff King <peff@peff.net>]

On Tue, Jun 22, 2021 at 07:06:43PM +0200, Ævar Arnfjörð Bjarmason wrote:

> > @@ -155,9 +156,10 @@ static int add_ref_decoration(const char *refname, const struct object_id *oid,
> >  		return 0;
> >  	}
> >  
> > -	obj = parse_object(the_repository, oid);
> > -	if (!obj)
> > +	objtype = oid_object_info(the_repository, oid, NULL);
> > +	if (type < 0)
> >  		return 0;
> > +	obj = lookup_object_by_type(the_repository, oid, objtype);
> 
> This series looks good. I just wonder if between this and my own
> lookup_{blob,tree,tag,commit}_type() in [1] whether exposing some
> function between what we have now in parse_object() and
> parse_object_buffer() wouldn't also do this for you.
> 
> I.e. in my patch if you pass a type into parse_object_buffer() I think
> you'll get the same behavior.

Maybe, but I'm having trouble seeing what would be a helpful
abstraction. I don't think I'd want to use parse_object_buffer() here;
we don't have a buffer at all (and obviously it could learn to handle
NULL, but that's extra code there).

parse_object_buffer() could call this lookup_object_by_type() to get the
struct, which would save it a few lines. But it still has to do the
if-else chain for each type, because it does other type-specific
things.

So I dunno. I would be happy if you came up with something, just because
it's nice to minimize the number of places that do this if-else/switch
on type. But I have a feeling it's diminishing returns in terms of
complexity. If we can at least contain it all to object.c, that's
something.

-Peff