Re: difflame

I have been "scripting around git blame --reverse" for some days now.
Mind taking a look? I've been working on blame-deletions for this.

22:41 $ ../difflame/difflame.py HEAD~5 HEAD

diff --git a/file b/file
index b414108..051c298 100644
--- a/file
+++ b/file

@@ -1,6 +1,9 @@

^1513353 (Edmundo 2017-02-02 22:41:45 -0600 1) 1
f20952eb (Edmundo 2017-02-02 22:41:45 -0600 2) 2
bb04dc7c (Edmundo 2017-02-02 22:41:45 -0600 3) 3
-de3c07b (Edmundo 2017-02-02 22:41:47 -060 4) 4
058ea125 (Edmundo 2017-02-02 22:41:45 -0600 4) 5
85fc6b81 (Edmundo 2017-02-02 22:41:45 -0600 5) 6
+2cd990a6 (Edmundo 2017-02-02 22:41:45 -0600 6) 7
+ab0be970 (Edmundo 2017-02-02 22:41:45 -0600 7) 8
+944452c0 (Edmundo 2017-02-02 22:41:45 -0600 8) 9
+6641edb0 (Edmundo 2017-02-02 22:41:45 -0600 9) 10


$ git show de3c07b
commit de3c07bc21a83472d5c5ddf172dcb742665924dd (HEAD -> master)
Author: Edmundo [off-list ref]
Date:   Thu Feb 2 22:41:47 2017 -0600

   drop 4

diff --git a/file b/file
index f00c965..051c298 100644
--- a/file
+++ b/file

@@ -1,7 +1,6 @@

1
2
3
-4
5
6
7


Next step: solve the
find-real-deletion-revision-when-there-are-multiple-child-nodes
problem.... and let me read the discussion around git blame --reverse.

Thanks in advance.

On Mon, Jan 30, 2017 at 8:37 PM, Edmundo Carmona Antoranz
[off-list ref] wrote:

Maybe a little work on blame to get the actual revision where some
lines were "deleted"?

Something like git blame --blame-deletion that could be based on --reverse?

On Mon, Jan 30, 2017 at 7:35 PM, Edmundo Carmona Antoranz
[off-list ref] wrote:

quoted

I'm thinking of something like this:

Say I just discovered a problem in a file.... I want to see who worked
on it since some revision that I know is working fine (or even
something as generic as HEAD~100..). It could be a number of people
with different revisions. I would diff to see what changed.... and
blame the added lines (blame reverse to try to get as close as
possible with a single command in case I want to see what happened
with something that was deleted). If I could get blame information of
added/deleted lines in a single run, that would help a lot.

Lo and behold: difflame.



On Mon, Jan 30, 2017 at 5:26 PM, Jeff King [off-list ref] wrote:

quoted

On Mon, Jan 30, 2017 at 01:08:41PM -0800, Junio C Hamano wrote:

quoted

Jeff King [off-list ref] writes:

quoted

On Tue, Jan 17, 2017 at 11:24:02PM -0600, Edmundo Carmona Antoranz wrote:

quoted

For a very long time I had wanted to get the output of diff to include
blame information as well (to see when something was added/removed).

This is something I've wanted, too. The trickiest part, though, is
blaming deletions, because git-blame only tracks the origin of content,
not the origin of a change.

Hmph, this is a comment without looking at what difflame does
internally, so you can ignore me if I am misunderstood what problem
you are pointing out, but I am not sure how "tracks the origin of
content" could be a problem.

If output from "git show" says this:

      --- a/file
      +++ b/file
      @@ -1,5 +1,6 @@
       a
       b
      -c
      +C
      +D
       d
       e

in order to annotate lines 'a', 'b', 'd', and 'e' for their origin,
you would run 'blame' on the commit the above output was taken from
(or its parent---they are in the context so either would be OK).

You know where 'C' and 'D' came from already.  It's the commit you
are feeding "git show".

I think the point (or at least as I understand it) is that the diff is
not "git show" for a particular commit. It could be part of a much
larger diff that covers many commits.

As a non-hypothetical instance, I have a fork of git.git that has
various enhancements. I want to feed those enhancements upstream. I need
to know which commits should be cherry-picked to get those various
enhancements.

Looking at "log origin..fork" tells me too many commits, because it
includes ones which aren't useful anymore. Either because they already
went upstream, or because they were cherry-picked to the fork and their
upstream counterparts merged (or even equivalent commits made upstream
that obsoleted the features).

Looking at "git diff origin fork" tells me what the actual differences
are, but it doesn't show me which commits are responsible for them.

I can "git blame" each individual line of the diff (starting with "fork"
as the tip), but that doesn't work for lines that no longer exist (i.e.,
when the interesting change is a deletion).

quoted

In order to run blame to find where 'c' came from, you need to start
at the _parent_ of the commit the above output came from, and the
hunk header shows which line range to find the final 'c'.

So perhaps that explains my comment more. "blame" is not good for
finding which commit took away a line. I've tried using "blame
--reverse", but it shows you the parent of the commit you are looking
for, which is slightly annoying. :)

"git log -S" is probably a better tool for finding that.

-Peff