1d ago

Introduction - Steve's Tutorial on Jujutsu, an alternative front-end to git

steveklabnik.github.io

Introduction - Steve's Jujutsu Tutorial

Jujutsu is essentially an alternative front-end or "porcelain" to git, both magnificiently simplified and powerful.

I tried it after using Emacs Magit for about six or seven years, and jujutsu is really easier to use than git and useful if one wants a tidy public history of changes (with "tidy" and "public" as Linus Torvalds recommends). Plus it is fully compatible to git as backend - other contributors will not even note you are using it.

Programming @programming.dev

HaraldvonBlauzahn @feddit.org

1d ago

Introduction - Steve's Tutorial on jujutsu, an alternative front-end to git

steveklabnik.github.io /jujutsu-tutorial/introduction/introduction.html

20 comments

Hrm... It looks interesting but it seems too dedicated to crafting "the perfect commit".
Changing our description changed the commit ID! This is why we have both IDs: the change ID has not changed, but the commit ID has. This allows us to evolve our commit over time, but still have a stable way to refer to all versions of it.
I don't want to "evolve a commit" - I want to capture my changes over time. If I decide later that I want to prepare the commit for merging I will.
I hate it because it's different - but even trying to give it a "benefit of the doubt" I really can't see this as better. It's not like it's difficult to create a "tidy" commit with git as is.
And as far as "easier to use goes"... well... Here's how you get a list of anonymous branches

jj log -r 'heads(all())'
And since they eschew branches with names you get to memorize hash strings instead of branch names that describe the thing you were doing?

jj new pzoqtwuv yykpmnuq -m "merge better documentation" # vs. git merge my_branch_Name
I'm unconvinced. Though jj undo looks neat (and also crazy dangerous unless you can undo an undo?).
- And since they eschew branches with names you get to memorize hash strings instead of branch names that describe the thing you were doing?
  No trouble, you can still name branches if you want. And no, you don't have to type the whole changeset hash, the first one to three letters are usually sufficient.
  Also, branch names are not a permanent thing, they disappear after you merged them.
  If you want, to can put an empty commit with the description of what you want to do at the top of your changes, and then use "jj split" to move changes to different commits before it. There are several common work flows which are explained in Klabnik's blog post.
- Yeah you can undo undo and also resurrect undone states.
  If the readability of the commit history really does not matter to you - for exsmple, nobody needs to read this code again - it's possible that jj does not give you enough advantage. Everyone works different.
  
  If the readability of the commit history really does not matter to you - for exsmple, nobody needs to read this code again - it’s possible that jj does not give you enough advantage. Everyone works different.
  I mean... It does and I will use git to manage commit histories as necessary. I don't see jj as solving that problem or even making it easier. Doing a single squash-commit or a rebase -i when I merge a branch is relatively trivial.
  And from what I can tell it's much easier to do a git pull upstream master than to do jj new skdfsld dskfjas since you'll likely have to lookup those hashes? I mean I wouldn't remember them.
I highly recommend giving Jujutsu a try. It didnt take long to learn at all and just feels so much more flexible and intuitive.
other contributors will not even note you are using it.
Ooooh, that's interesting.
- Technically true - but it looks like jj does a lot of history re-writing which would require a lot of care to be taken when working on a shared codebase.
  The page on remotes has some cautions in it.
  We need the --allow-backwards flag to set the trunk branch to the previous commit because it is a dangerous operation: if we had pushed trunk, things would get weird when we try and push now. We've kept it all local, so there's no issues with doing this.
  
  jj by default refuses to change any commits on published branches such as a master branch that has been pushed. The details are configurable.
  BTW that's why I linked Linus Torvalds mail on when and why to rewrite history - it is good advice.
- Another useful property is that while jujutsu does have worktrees, like git, in many cases where one would use git worktrees (for example when writing accompanying documentation ) it is just easier to use another line of changes (what is a branch in git).
  Alas, that jujutsu does not store local change sets automatically on a remote git repo (this happens only when you update and push a git branch), means that still-mutable local changes are not automatically transferred to another computer you work on. And unpublished changes are naturally mutable in jujutsu. But you can safely copy a jj repo via rsync, as changes in jj metadata are thread-safe and atomic. The other way is of course to push a work-in-progress ("WIP") git branch which can muate and is therefore not allowed to be merged by other people.
  
  That’s not really how one would use worktrees in git. Worktrees are useful in the case when e.g. you are working on version 0.15 of your software that has many breaking changes to version 0.14 (perhaps even on a build system level) and you need to release a 0.14.1 patch. Worktrees separate directories which means you don’t need to stash or do a wip commit, nor clear you 0.15 build artefacts. Just cd to a different worktree, checkout the 0.14 branch, create and checkout the 0.14.1 branch, clear build artifacts in a different directory from your main development one, and start working.
  When done, just cd back and keep working again without switching branches, clearing artifacts, or doing full rebuilds of the in-development 0.15 version.
  Plus, git does not store change sets or branches or anything on any remote unless you push them either, so if you’re having that problem just stop pushing things you don’t want to push. You can totally rsync a git repo, just ensure it’s at rest. Otherwise do what you should be doing anyway: set the repo on another machine as a remote of the other repo, so you can git pull my_private_machine feature/my_private_branch without needing to push to a central repo.
  I’m sure jujutsu has many advantages, but it also reads to me like you’re misunderstanding the git model. Which can be a fair critique of git to be fair, but then we would need to talk about what about the git model people have trouble with, why, and how to address those issues, and so far I haven’t seen any kind of research in that direction from jujutsu (not that I’ve been looking particularly hard)
Currently it works just as frontend for git, but it theoretically supports other backends too. Allegedly Google has their own experimental internal cloud+db based backend for big monorepos.

20 comments