Unmerge

Important

You discover that undoing a merge is trivial.

How do you unmerge?

@    nvn      ▢ Here's the merge
├─╮
│ ○  o        Play instructions **manual**
│ ○  kx       Play manual
○ │  z        Click alternates Xs and Os **dev**
○ │  v        Click sets a X
○ │  s        Square has state
├─╯
│
~

Easy! If merging was your last operation, just use jj undo:

jj undo

○  o        Play instructions **manual**
○  kx       Play manual
│ ○  z        Click alternates Xs and Os **dev**
│ ○  v        Click sets a X
│ ○  s        Square has state
├─╯
│
~

Unmerging With abandon

Alternatively, you could jj abandon the merge Change. Let’s try it. First, start over:

jj redo

Yes! As seen in the Quick Start, you can undo an undo . Jujutsu’s undo works like Emacs’: instead of merely going back in time, it appends the revert operation to a log. No information is ever lost. Curious? Read Emacs’ Undo.

You are back to:

@    vz          Here's the merge
├─╮
│ ○  o          Play instructions instructions **dev**
│ ○  kx         Play manual
○ │  z          Click alternates Xs and Os **manual**
○ │  vv         Click sets a X
○ │  s          Square has state
├─╯
~

Do yourself a favor: move somewhere else before deleting the merge, or you’ll abandon your Current Change¹:

jj edit n

Your turn.

Warning

Unmerge without using undo.

Tip

Elementary, my dear Watson!

jj abandon vz

○  o        Play instructions **manual**
○  kx       Play manual
│ ○  z        Click alternates Xs and Os **dev**
│ ○  v        Click sets a X
│ ○  s        Square has state
├─╯
~

Can you merge more than 2 Changes? Sure! In Git this is called an “octopus merge”: it’s rare enough to be considered an anti-pattern. Jujutsu embraces it, instead. You’ll see fancy workflows based on it.

Warning

Now, create an octopus merge between css, manual and dev:

Tip

jj new -r css -r manual -r dev

@      kn       ▢
├─┬─╮
│ │ ○  z        Click alternates Xs and Os **dev**
│ │ ○  v        Click sets a X
│ │ ○  s        Square has state
│ ○ │  o        Play instructions **manual**
│ ○ │  kx       Play manual
│ ├─╯
○ │  qn       Add the CSS file **css**
○ │  rt       Link to CSS
├─╯
~

Too easy? See? You already think like a jujutsuka!
Notice: you merged the tips of 3 branches, but nothing stopped you from referencing a Change that wasn’t at a branch tip.

In Git, undoing a merge ranges from easy to painful, depending on your experience. Jujutsu makes it trivial regardless.

1. Abandoning the Current Change is perfectly legit, but it might surprise you the first time. Read Pulling the Rug Out Under Oneself for details. ↩