Hi!
Since my last post the biggest improvement is the ability to detect
that the user has requested a "reverse" analysis.
Under "normal" circumstances a user would ask difflame to get the diff
from an ancestor (call "difflame treeish1 treeish2" so that merge-base
of treeish1 treeish2 equals treeish1). In this case the blame result
is done using straight blame output for added lines and additional
analysis to detect where a line was deleted (analysis has improved a
lot in this regard.... I haven't heard anything from Peff, though).
But if the user requests the opposite (call "difflame treeish1
treeish2" so that merge-base of treeish1 treeish2 is treeish2) then
the analysis has to be driven "in reverse".
Here's one example taken from difflame itself:
normal "forward" call (hope output doesn't get butchered):
$ ./difflame.py HEAD~3 HEAD~2
diff --git a/difflame.py b/difflame.py
index e70154a..04c7577 100755
--- a/difflame.py
+++ b/difflame.py
@@ -365,7 +365,7 @@ def get_full_revision_id(revision):
e5b218e4 (Edmundo 2017-02-01 365) # we already had the revision
50528377 (Edmundo 2017-03-04 366) return REVISIONS_ID_CACHE[revision]
d1d11d8a (Edmundo 2017-02-02 367) # fallback to get it from git
b1a6693 use rev-list to get revision IDs
-b1a6693 (Edmundo 2017-03-04 368) full_revision =
run_git_command(["show", "--pretty=%H", revision]).split("\n")[0]
+b1a66932 (Edmundo 2017-03-04 368) full_revision =
run_git_command(["rev-list", "--max-count=1",
revision]).split("\n")[0]
50528377 (Edmundo 2017-03-04 369) REVISIONS_ID_CACHE[revision] =
full_revision
e5b218e4 (Edmundo 2017-02-01 370) return full_revision
91b7d3f5 (Edmundo 2017-01-31 371)
"reverse" call:
$ ./difflame.py HEAD~2 HEAD~3
diff --git a/difflame.py b/difflame.py
index 04c7577..e70154a 100755
--- a/difflame.py
+++ b/difflame.py
@@ -365,7 +365,7 @@ def get_full_revision_id(revision):
e5b218e4 (Edmundo 2017-02-01 365) # we already had the revision
50528377 (Edmundo 2017-03-04 366) return REVISIONS_ID_CACHE[revision]
d1d11d8a (Edmundo 2017-02-02 367) # fallback to get it from git
b1a6693 use rev-list to get revision IDs
-b1a66932 (Edmundo 2017-03-04 368) full_revision =
run_git_command(["rev-list", "--max-count=1",
revision]).split("\n")[0]
+b1a6693 (Edmundo 2017-03-04 368) full_revision =
run_git_command(["show", "--pretty=%H", revision]).split("\n")[0]
50528377 (Edmundo 2017-03-04 369) REVISIONS_ID_CACHE[revision] =
full_revision
e5b218e4 (Edmundo 2017-02-01 370) return full_revision
91b7d3f5 (Edmundo 2017-01-31 371)
Notice how the revision reported in both difflame calls is the same:
$ git show b1a66932
commit b1a66932704245fd653f8d48c0a718f168f334a7
Author: Edmundo Carmona Antoranz <whocares@xxxxxxxxx>
Date: Sat Mar 4 13:59:50 2017 -0600
use rev-list to get revision IDs
diff --git a/difflame.py b/difflame.py
index e70154a..04c7577 100755
--- a/difflame.py
+++ b/difflame.py
@@ -365,7 +365,7 @@ def get_full_revision_id(revision):
# we already had the revision
return REVISIONS_ID_CACHE[revision]
# fallback to get it from git
- full_revision = run_git_command(["show", "--pretty=%H",
revision]).split("\n")[0]
+ full_revision = run_git_command(["rev-list", "--max-count=1",
revision]).split("\n")[0]
REVISIONS_ID_CACHE[revision] = full_revision
return full_revision
If this "detection" to perform reverse analysis hadn't been done, then
there wouldn't be a lot of useful information because there are no
revisions in HEAD~2..HEAD~3 and so the output would have been
something like:
diff --git a/difflame.py b/difflame.py
index 04c7577..e70154a 100755
--- a/difflame.py
+++ b/difflame.py
@@ -365,7 +365,7 @@ def get_full_revision_id(revision):
e5b218e4 (Edmundo 2017-02-01 365) # we already had the revision
50528377 (Edmundo 2017-03-04 366) return REVISIONS_ID_CACHE[revision]
d1d11d8a (Edmundo 2017-02-02 367) # fallback to get it from git
b1a6693 use rev-list to get revision IDs
%b1a6693 (Edmundo 2017-03-04 368) full_revision =
run_git_command(["rev-list", "--max-count=1",
revision]).split("\n")[0]
e5b218e printing hints for deleted lines
+e5b218e4 (Edmundo 2017-02-01 368) full_revision =
run_git_command(["show", "--pretty=%H", revision]).split("\n")[0]
50528377 (Edmundo 2017-03-04 369) REVISIONS_ID_CACHE[revision] =
full_revision
e5b218e4 (Edmundo 2017-02-01 370) return full_revision
91b7d3f5 (Edmundo 2017-01-31 371)
Notice how both the added line and the deleted line are reporting the
_wrong_ revision. It should be b1a66932 in all cases.
One question that has been bugging me for a while is what to do in
cases where treeish1, treeish2 are not "direct" descendants" (as in
merge-base treeish1 treeish2 is something other than treeish1 or
treeish2). Suppose a line was added on an ancestor of treeish1 but it
hasn't been merged into treeish2. In this case if we diff
treeish1..treeish2 we will get a _deleted_ line. However analysis to
find a deleting revision in treeish1..treeish2 will fail. I'm
wondering if it would be ok in this case to blame the deleted line on
the ancestor if treeish1 where the line was _added_.
Another thing I added is the support to use tags.
Best regards!