Re: [PATCH v3] reset: add an example of how to split a commit into two
From: Junio C Hamano <hidden>
Date: 2017-02-16 19:19:55
Jacob Keller [off-list ref] writes:
The interdiff between v2 and v3 is not really worth showing since I basically re-wrote the entire section a bit.
Could this be made into an incremental, now that v2 has been in 'next' for about 10 days, please?
quoted hunk
+Split a commit apart into a sequence of commits:: ++ +Suppose that you have create lots of logically separate changes and commit them
s/create/&d/; s/commit/&ed/
quoted hunk
+together. Then, later you decide that it might be better to have each logical +chunk associated with its own commit. You can use git reset to rewind history +without changing the contents of your local files, and then successively use +git add -p to interactively select which hunks to include into each commit, +using git commit -c to pre-populate the commit message. ++ +------------ +$ git reset -N HEAD^ <1> +$ git add -p <2> +$ git diff --cached <3> +$ git commit -c HEAD@{1} <4> +... <5> +$ git add ... <6> +$ git diff --cached <7> +$ git commit ... <8> +------------ ++ +<1> First, reset the history back one commit so that we remove the original + commit, but leave the working tree with all the changes. The -N ensures + that any new files added with HEAD are still marked so that git add -p + will find them. +<2> Next, we interactively select diff hunks to add using the git add -p + facility. This will ask you about each diff hunk in sequence and you can + use simple commands such as "yes, include this", "No don't include this" + or even the very powerful "edit" facility. +<3> Once satisfied with the hunks you want to include, you should verify what + has been prepared for the first commit by using git diff --cached. This + shows all the changes that have been moved into the index and are about + to be committed. +<4> Next, commit the changes stored in the index. The -c option specifies to + pre-populate the commit message from the original message that you started + with in the first commit. This is helpful to avoid retyping it. The HEAD@{1} + is a special notation for the commit that HEAD used to be at prior to the + original reset commit (1 change ago). See linkgit:git-reflog[1] for more + details. You may also use any other valid commit reference. +<5> You can repeat steps 2-4 multiple times to break the original code into + any number of commits. +<6> Now you've split out many of the changes into their own commits, and might + no longer use the patch mode of git add, in order to select all remaining + uncommitted changes. +<7> Once again, check to verify that you've included what you want to. You may + also wish to verify that git diff doesn't show any remaining changes to be + committed later. +<8> And finally create the final commit. +
Nicely done. We could talk more "best practice" things in this sequence (e.g. "'stash --keep' then test in isolation"), but it is already sufficiently long, so extending it may hurt the readability more than it helps by guiding the readers to better ways.