Re: [PATCH v2] Fix notes handling in rev-list

On Mon, Jul 16, 2012 at 10:42:07PM -0700, Junio C Hamano wrote:

quoted

Just like log, the notes are part of the commit information to the right
of the graph. But this second hunk is for when we are not using the
pretty-printer at all, and the output looks like this:

  $ git rev-list --graph --notes -2 HEAD
  * f6bbb09529a4cc73446c7c115ac1468477bd0cc6

  Notes:
      foobar
  * 31c79549b85c6393be4f40432f5b86ebc097fc7e

which doesn't make sense

I actually have quite a different feeling about this.  As I said in
the separate message, I think --graph, or anything that makes the
output unparsable or harder to parse for machines for that matter,
in rev-list are not something we have because we wanted to support
them, but that which just happen to work because the large part of
rev-list and log can share building blocks to do similar things.
The key phrase is "can share" here; it does not necessarily mean
they "should" [*1*].

Somebody went to the trouble to make "rev-list --graph" work[1] (that is
what the call to graph_show_remainder in the else clause of the
conditional is about). I agree it seems kind of useless, but it does
work now, and we should at least not make it worse (and I think we both
agree that the output above is just wrong).

So whatever we show for a note, it should look like:

  * f6bbb095...
  | the notes thing to show
  * 31c79549...

Because that is how graph output is formatted. Either that, or we should
disallow --graph entirely with rev-list (which I'd also be OK with).

I do not mind having an option to show the notes text, but I doubt
it is a sane thing to do to make "rev-list --notes" unconditionally
show the payload of the notes blob.  "rev-list --objects" only shows
the object names of trees and blobs, not the payload in these
objects, and this is very much on purpuse.  It allows the downstream
process that reads its output from the pipe to easily parse the
output and choose to do whatever it wants to do using them.

I wonder if we should show the blob object names that store the
notes payload if we were given --notes option in a format that is
easy for readers to mechanically parse its output.

So leaving aside the --graph issues, we would need to decide what to
show in the non-graph case. And I think your suggestion is good; there
is no real need to dereference the blob (if you want that, you can turn
on the pretty-printer).

I'm just not sure what the output should be. I guess:

  <commit_sha1> <notes sha1s>

is probably the most sensible (it's sort of like --parents). And that
solves the --graph issue, too, since it continues to take only a single
line.

-Peff

[1] Looking at the code, I do think somebody wanted "rev-list --graph"
to work, and it is not an accident. But I think they did not do a very
thorough job, as things like "git rev-list --objects --graph" produce
nonsensical output.