Git Branches: Intuition and Reality

Post by bloopernova » Thu, Nov 23, 2023, 5:30 PM UTC

bloopernova wrote: post #97

bloopernova wrote: post #65

tl;dr Please ignore, just me working through a Python+pygit2 problem. I solved it in a grandchild comment. I had so much trouble trying to map my intuited/mental model of git onto pygit2 that I gave up and just used the git module. I wanted to automate a fairly simple thing in Python as opposed to bash+commands. My reasoning being that I wanted to do it "right" and be a Big Programmer Real Boy(tm). I just wanted to c…

This isn't asking someone else to make this work, it's more of a caution to convince folks like me to just use "import git" rather than pygit2: So something like this was what I expected to work, but leaves the repo in detached head state: import pygit2 def checkout_branch(path, branch_name): repo = pygit2.Repository(path) branch_ref = repo.lookup_reference(f"refs/remotes/origin/{branch_name}") print(f"{branch_ref.na…

    def checkout_branch(path, branch_name):
        repo = pygit2.Repository(path)

        main_branch = repo.lookup_branch("main")
        print(f"Main branch upstream: {main_branch.upstream_name}")

        if branch_name not in repo.branches.local:
            print(f"Branch {branch_name} not found in local branches")
            remote_branch = "origin/" + branch_name
            if remote_branch not in repo.branches.remote:
                raise SystemExit(f"Branch {remote_branch} not found in remote branches")
            (commit, remote_ref) = repo.resolve_refish(remote_branch)
            repo.create_reference("refs/heads/" + branch_name, commit.hex)

        branch = repo.lookup_branch(branch_name)
        print(f"Branch name: {branch.name}")

        repo.checkout(branch)
        print(f"Is branch head? {branch.is_head()}")

        (commit, branch_remote) = repo.resolve_refish("origin/" + branch_name)
        print(f"Remote branch: {branch_remote.name}")
        branch.upstream = branch_remote

    d44aedc (HEAD -> test, origin/test) HEAD@{0}: checkout: moving from main to test

Post by someone7x » Thu, Nov 23, 2023, 5:34 PM UTC

still_grokking wrote: post #94

mixedmath wrote: post #4

Earlier quoted context omitted.

Possibly `git branch NEWBRANCHNAME` instead of `git checkout -b NEWBRANCHNAME`. When I need to show git to someone in order for them to contribute to something, I give them only these incantations --- and instructions to ask me if weird git things happen.

It's `git switch [-c]` nowadays.

    git switch -c foo
    git push 
    > did you mean git push --args-with-branch-name?
    sigh, copy, paste, enter

Post by intrepidsoldier » Thu, Nov 23, 2023, 5:40 PM UTC

Post by TeMPOraL » Thu, Nov 23, 2023, 5:43 PM UTC

mr_mitm wrote: post #121

skrebbel wrote: post #101

Earlier quoted context omitted.

For years I was deeply annoyed by the terrible name “branch” for something that acts more like a bookmark (or “wandering tag” indeed!). And then I learned that git branches are branches in exactly the same way that the first element of a linked list in C “is” the linked list. Git was made by C people and they’re used to referring to entire data structures by way of some root element. I mean that doesn’t make me disli…

When the entire structure of commits is called a tree, I find the name "branch" fitting. The branch is identified by its head commit, so the path from head to root is uniquely defined and that's the branch. (Disregarding merges for now.)

Post by ajross » Thu, Nov 23, 2023, 5:56 PM UTC

skrebbel wrote: post #101

riperoni wrote: post #44

While the explanation is right in some sense, it misses a few points. Branches are pointers to a commit and that pointer is refreshed when a new commit is created. One could say they are a wandering tag (without explaining a tag for now). The actual chain of commits that represent what we see as branch comes from the commits themselves. Those commits point back to their parent commit. And then one can see why no bran…

For years I was deeply annoyed by the terrible name “branch” for something that acts more like a bookmark (or “wandering tag” indeed!). And then I learned that git branches are branches in exactly the same way that the first element of a linked list in C “is” the linked list. Git was made by C people and they’re used to referring to entire data structures by way of some root element. I mean that doesn’t make me disli…