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On Not Being There

A quick thought, before moving to more exciting features.

What's the Git command for merging the branch A with the branch B? Those who mostly use IDE plugins and rarely touch the terminal might answer, caught off guard:

git merge A B

The correct answer is:

Answer

It depends.

  • If the current branch is A, then it's git merge B.
  • If the current branch is B, then it's git merge A.
  • If it's neither, then you need git checkout A && git merge B.

With git merge the current branch is always assumed.

Why Is It Like That?

Why isn't it git merge A B? Why do commands like cherry-pick, rebase, pull and am assume the current branch as an implicit argument?

Because of conflicts. When something goes wrong, Git cannot store the result as a commit. It stops and asks you to resolve the problem first, and the only place where you can do that is the file system. So, you have to be there.

And Jujutsu?

You probably noticed: when merging with Jujutsu you don't have to be anywhere in particular. You select the parents A and B without being in either. You also abandon Changes from a distance. You can even commit from a distance.

This follows from the fact Jujutsu handles conflicts as first-class citizens. You'll learn what a lifesaver this is later on but, for now, just get the gist: you can operate on Changes without being there.