Re: A new idea to extend git-blame

>
> On Wed, Nov 27, 2019 at 06:32:37PM +1100, chen bin wrote:
>
> > Just double checking, the feature I suggested is fine, right? I will
> > send the patch asap. It may take 2 weeks to implement.
>
> To be clear, I can't say whether a patch is fine or not without seeing
> the patch. :)
>
> I'm not entirely sure I understand what you're proposing to implement.
> But if it's of interest to you, maybe it makes sense to see if you can
> make it work to your satisfaction, and then we can all look at the patch
> and what it does to see if it makes sense to include in Git?
>
> > > > I re-tested `git log -L20,20:README.md` in git's own repo with HEAD
> > > > d01d26f2df. Looks git log is not what I expected. The output contains
> > > > many unrelated commits. So it will be slow in real project.
>
> Looking at the output from that command, the issue is that it's
> imperfect to decide which lines in the pre- and post-image correspond to
> each other. The first commit is:
>
>   diff --git a/README.md b/README.md
>   --- a/README.md
>   +++ b/README.md
>   @@ -26,3 +26,1 @@
>   -See Documentation/gittutorial.txt to get started, then see
>   -Documentation/giteveryday.txt for a useful minimum set of commands, and
>   -Documentation/git-commandname.txt for documentation of each command.
>   +See [Documentation/gittutorial.txt][] to get started, then see
>
> at which point we consider all three of the pre-image lines to be
> potentially interestnig. And then the next commit:
>
>   diff --git a/README b/README
>   --- a/README
>   +++ b/README
>   @@ -29,3 +29,3 @@
>    See Documentation/gittutorial.txt to get started, then see
>   -Documentation/everyday.txt for a useful minimum set of commands, and
>   +Documentation/giteveryday.txt for a useful minimum set of commands, and
>    Documentation/git-commandname.txt for documentation of each command.
>
> touches one of those lines, and so forth. A human might see that in the
> first hunk, it was probably the first line of the hunk that was
> interesting to keep following backwards. But I don't think it can be
> done automatically (which is why manual "reblame from parent" is still a
> useful technique).
>
> It sounds like your suggestion is to take some anchor text on the line
> to decide which lines to keep following. But then it sounds a lot more
> like a "log -L" feature than a git-blame feature.
>
> -Peff