mirror of
https://github.com/git/git.git
synced 2024-11-25 02:44:48 +08:00
5b766ea901
This howto consists of a footnote from an email by JC to the git mailing list (<7vfyms0x4p.fsf@assigned-by-dhcp.cox.net>). Signed-off-by: Kent Engstrom <kent@lysator.liu.se> Signed-off-by: Junio C Hamano <junkio@cox.net>
92 lines
3.2 KiB
Plaintext
92 lines
3.2 KiB
Plaintext
From: Junio C Hamano <junkio@cox.net>
|
|
Subject: Separating topic branches
|
|
Abstract: In this article, JC describes how to separate topic branches.
|
|
|
|
This text was originally a footnote to a discussion about the
|
|
behaviour of the git diff commands.
|
|
|
|
Often I find myself doing that [running diff against something other
|
|
than HEAD] while rewriting messy development history. For example, I
|
|
start doing some work without knowing exactly where it leads, and end
|
|
up with a history like this:
|
|
|
|
"master"
|
|
o---o
|
|
\ "topic"
|
|
o---o---o---o---o---o
|
|
|
|
At this point, "topic" contains something I know I want, but it
|
|
contains two concepts that turned out to be completely independent.
|
|
And often, one topic component is larger than the other. It may
|
|
contain more than two topics.
|
|
|
|
In order to rewrite this mess to be more manageable, I would first do
|
|
"diff master..topic", to extract the changes into a single patch, start
|
|
picking pieces from it to get logically self-contained units, and
|
|
start building on top of "master":
|
|
|
|
$ git diff master..topic >P.diff
|
|
$ git checkout -b topicA master
|
|
... pick and apply pieces from P.diff to build
|
|
... commits on topicA branch.
|
|
|
|
o---o---o
|
|
/ "topicA"
|
|
o---o"master"
|
|
\ "topic"
|
|
o---o---o---o---o---o
|
|
|
|
Before doing each commit on "topicA" HEAD, I run "diff HEAD"
|
|
before update-index the affected paths, or "diff --cached HEAD"
|
|
after. Also I would run "diff --cached master" to make sure
|
|
that the changes are only the ones related to "topicA". Usually
|
|
I do this for smaller topics first.
|
|
|
|
After that, I'd do the remainder of the original "topic", but
|
|
for that, I do not start from the patchfile I extracted by
|
|
comparing "master" and "topic" I used initially. Still on
|
|
"topicA", I extract "diff topic", and use it to rebuild the
|
|
other topic:
|
|
|
|
$ git diff -R topic >P.diff ;# --cached also would work fine
|
|
$ git checkout -b topicB master
|
|
... pick and apply pieces from P.diff to build
|
|
... commits on topicB branch.
|
|
|
|
"topicB"
|
|
o---o---o---o---o
|
|
/
|
|
/o---o---o
|
|
|/ "topicA"
|
|
o---o"master"
|
|
\ "topic"
|
|
o---o---o---o---o---o
|
|
|
|
After I am done, I'd try a pretend-merge between "topicA" and
|
|
"topicB" in order to make sure I have not missed anything:
|
|
|
|
$ git pull . topicA ;# merge it into current "topicB"
|
|
$ git diff topic
|
|
"topicB"
|
|
o---o---o---o---o---* (pretend merge)
|
|
/ /
|
|
/o---o---o----------'
|
|
|/ "topicA"
|
|
o---o"master"
|
|
\ "topic"
|
|
o---o---o---o---o---o
|
|
|
|
The last diff better not to show anything other than cleanups
|
|
for crufts. Then I can finally clean things up:
|
|
|
|
$ git branch -D topic
|
|
$ git reset --hard HEAD^ ;# nuke pretend merge
|
|
|
|
"topicB"
|
|
o---o---o---o---o
|
|
/
|
|
/o---o---o
|
|
|/ "topicA"
|
|
o---o"master"
|
|
|