Cyclopedia Square

Git branches have confused me (someone who uses mercurial a lot and git a little) for a while, I have finally realized why. The problem is that git branch is a poorly chosen name for the thing that they really are. You see, all the changeset history in git is stored as a Directed Acyclic Graph (DAG). The code history might be simple and linear which will make the DAG have a simple path like so (o's are nodes in the graph, called changesets, -'s are references from one node to another, with time progressing from left to right): o-o-o-o-o Or the code history and corresponding DAG could be more complicated: o-o-o / o-o-o o-o-o-o-o / \ / \ o-o-o-o-o-o-o-o-o-o-----o-o Most English language speakers would agree that those parts of the DAG (code history) where a node has two children (representing two parallel lines of development) are called, branches. The above example has four branches in the history, four branche...

In my last post I pondered (ranted?) on the reluctance of Mercurial people to edit repository history, especially as compared to git people. Today I noticed that Mercurial 2.1 has been released, and it has a new feature that makes editing your local repository much safer, phases (more detail here ). To me this looks like a really cool idea. Phases explicitly mark changesets as either public (have been pushed or pulled, and should not be edited) or draft (still local to your repository and can be freely edited). Changesets are given a phase automatically behind the scenes (though you can override this, of course), and history editing tools respect phases so that now it is even harder to shoot yourself in the foot when editing your repository history with tools like rebase or mq. There is also one more phase, secret, that can be enabled for use with patches in your Mercurial Queues. Secret changesets will not be pushed, pulled, or cloned (or even show up in the output of incomi...

I just installed the very latest version of mercurial, 2.0.2 . It added a new little feature that warns you when you create a branch. Huh? This is what it looks like: $ hg branch foo marked working directory as branch foo (branches are permanent and global, did you want a bookmark?) Really? Have we let the git advocates push us this far? Do we really need to start discouraging named branches? I googled around to see if I could find where the self-hate for mercurial's named branches is coming from and I found things like this , "it is almost never a good idea to use this facility for short-term branching, since branches created this way are inherently 'eternal'." (those quotes around eternal are good, actually, but you didn't explain why they should be there), and this , "you can never really delete branches (since that would mean altering older commits)." (editing history, oh noes!), and others like this. And these were all written by a...