Re: [PATCH 1/8] pack-bitmap: initialize `bitmap_writer_init()` with packing_data

> On Thu, Aug 15, 2024 at 01:31:00PM -0400, Taylor Blau wrote:
>
> > In order to determine its object order, the pack-bitmap machinery keeps
> > a 'struct packing_data' corresponding to the pack or pseudo-pack (when
> > writing a MIDX bitmap) being written.
> >
> > The to_pack field is provided to the bitmap machinery by callers of
> > bitmap_writer_build() and assigned to the bitmap_writer struct at that
> > point.
> >
> > But a subsequent commit will want to have access to that data earlier on
> > during commit selection. Prepare for that by adding a 'to_pack' argument
> > to 'bitmap_writer_init()', and initializing the field during that
> > function.
> >
> > Subsequent commits will clean up other functions which take
> > now-redundant arguments (like nr_objects, which is equivalent to
> > pdata->objects_nr, or pdata itself).
>
> This (and the next few follow-on commits) seem like a good change to me.
> It simplifies many of the function calls, and I think it expresses the
> domain logic in the API: there is a single set of objects being mapped
> to bits, and many parts of the process will rely on it.

> Even the midx code, which is not generating a pack, uses a "fake"
> packing_data as the way to express that (because inherently the bit
> ordering is all coming from the pack-index nature). If we likewise ever
> wrote code to generate bitmaps from an existing pack, it would probably
> use packing_data, too. :)