Re: [RFC PATCH] Implement vc-git-annotate-show-diff-revision-at-line for emacs vc-git

Alex Bennee [off-list ref] writes:

+(defun vc-git-annotate-extract-revision-at-line ()
+  (save-excursion
+    (move-beginning-of-line 1)
+    (and (looking-at "[0-9a-f]+")
+         (buffer-substring (match-beginning 0) (match-end 0)))))

Does this grab the commit object name from the annotation
of a _full_ file?  How is the annotation done?  With "blame"
without frills?

It may be interesting to run:

	git blame -w -n -f -C -- $path

which would give you the code movement (ignoring whitespace
changes) across files, so that you can view where the line
really originated from.

You can also throw in -L line range limiter like this:

	git blame -L$lineno-10,+20 -w -n -f -C -- $path

which would limit the output to lines around the current line,
and that would be slightly less expensive than annotating the
whole file, if you do this on-demand.

E.g.

	$ git blame -L48,+20 -w -n -f -C -- block/blk-exec.c

would give you something like:

    165125e1 block/ll_rw_blk.c         2585 (Jens Axboe       2007-07-2...
    f1970baf drivers/block/ll_rw_blk.c 2255 (James Bottomley  2005-06-2...
    8ffdc655 block/ll_rw_blk.c         2320 (Tejun Heo        2006-01-0...
    f1970baf drivers/block/ll_rw_blk.c 2257 (James Bottomley  2005-06-2...
    f1970baf drivers/block/ll_rw_blk.c 2258 (James Bottomley  2005-06-2...
    f1970baf drivers/block/ll_rw_blk.c 2259 (James Bottomley  2005-06-2...
    f1970baf drivers/block/ll_rw_blk.c 2260 (James Bottomley  2005-06-2...
    4aff5e23 block/ll_rw_blk.c         2530 (Jens Axboe       2006-08-1...
    f1970baf drivers/block/ll_rw_blk.c 2262 (James Bottomley  2005-06-2...
    4c5d0bbd block/ll_rw_blk.c         2480 (Andrew Morton    2006-03-2...
    4c5d0bbd block/ll_rw_blk.c         2481 (Andrew Morton    2006-03-2...
    4c5d0bbd block/ll_rw_blk.c         2482 (Andrew Morton    2006-03-2...
    4c5d0bbd block/ll_rw_blk.c         2483 (Andrew Morton    2006-03-2...
    4c5d0bbd block/ll_rw_blk.c         2484 (Andrew Morton    2006-03-2...
    f1970baf drivers/block/ll_rw_blk.c 2265 (James Bottomley  2005-06-2...
    6e39b69e block/ll_rw_blk.c         2309 (Mike Christie    2005-11-1...
    6e39b69e block/ll_rw_blk.c         2310 (Mike Christie    2005-11-1...
    637b48c8 drivers/block/ll_rw_blk.c 1872 (Jens Axboe       2004-03-1...
    637b48c8 drivers/block/ll_rw_blk.c 1873 (Jens Axboe       2004-03-1...
    637b48c8 drivers/block/ll_rw_blk.c 1874 (Jens Axboe       2004-03-1...