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> It seems like the natural way to me. What do you think the natural way is? A branch is a DAG of commits terminating at one commit. They should have just cal

> It seems like the natural way to me. What do you think the natural way is? A branch is a DAG of commits terminating at one commit. They should have just called it a pointer if it's a pointer. But here we are anyway.

lakpan 3y ago
That’s not right. A branch is a single pointer to a single commit. Just open your .git folder. It’s then Git itself that follows that commit’s pointer to its parent(s). The branch, like the tag, is a single reference to a commit. Do this: $ cat .git/refs/heads/main
- Buttons840 3y ago
  It seems accurate enough to say the branch includes all the parents of the pointed to commit. It's a matter of definition, but both definitions are technically accurate. (Also, note the path you ask us to cat does not contain the word "branch". You refer to how things are stored to support your definition, but the way things are stored doesn't use the term "branch".)
- Espressosaurus 3y ago
  The question was "what do you think is the most natural way to think about it", not "how does git represent it".
  - lakpan 3y ago
    What? If you’re looking for “the most natural” then you’ll find it in the name. You can’t “explain” branch by using a synonym. Plus that definition describes both tags and branches, how do you tell them apart? It’s clearly lacking. Actually that definition fits commits too. I’d rather use these: Branch: a pointer that advances Tag: a permanent pointer Commit/hash: an even more permanent pointer (because even a force can’t change it) that also describes the changes.
- seba_dos1 3y ago
  Technically, you're right. Practically however, it does make sense to implicitly dereference the branch you're talking about to the commit it points to. Asking "is this commit on that branch?" is semantically equivalent to "is this commit reachable from the commit that branch points to?". That said, it only makes sense to make such implicit mental shortcuts once you're already comfortable with git's data model. If you're not and you're still learning it, it's only going to confuse you.
  - lakpan 3y ago
    To be honest, describing a branch the wrong way is only going to confuse people more. The “dots on the line” visualization is pretty clear: you can have any number of branches pointing to a specific dot/commit. How do you add “branches” without fundamentally breaking that concept? When you create a branch, you’re not copying the line, you’re just adding a pointer.
Buttons840 3y ago
Are you saying that the "natural way" you think about branches is as a DAG terminating at one point? Because that is true; that is accurate. Thus, I don't understand your original claim that branches work in an unintuitive way.
- Espressosaurus 3y ago
  A branch in Git is just the pointer to the tip of the DAG. The way I find it natural to think about is it's the entire DAG of commits. To put this in programming terms, a git branch is a pointer. I think of a branch as the value is the most natural way to think about it. This mismatch is what leads to endless tutorials on what git actually means when it uses its vocabulary.
  - Buttons840 3y ago
    If I created my own git implementation with the exact same CLI, but under the hood I didn't use a "pointer", but instead used the "value", would this be more intuitive to you? One problem I'm trying to express with that question is: You say it's unintuitive, but when asked why you refer to a very low level technical detail. My suspicion is that people find git branches unintuitive, and thus they think something more intuitive must exist. They have vague ideas about what "more intuitive" might mean, usually it means "just do what I want in this one situation I'm currently facing". My theory is that, if pressed, nobody can fully define a behavior for branches that is more intuitive than the current git implementation.
    - Espressosaurus 3y ago
      Well, you're still using the same CLI which is part of the problem. Git's CLI reflects its patched-together-hacked-executable history. It shouldn't be controversial to say the porcelain can and should be much more straightforward to use. DVCS concepts like the DAG and where you want to apply diffs are complicated the first time around, but after you get the concepts it should be easy to use, not difficult. Mercurial's branches are a better match for how I've seen branches use in practice. Tags are essentially the same between both. Evolve's hidden commits make it easier to recover lost data than Git's reflog, though the underlying implementation not permitting garbage collection kind of sucks.
cryptonector 3y ago
> A branch is a DAG of commits terminating at one commit. [Pedantically] this includes orphaned branches. > They should have just called it a pointer if it's a pointer. A branch in every VCS is first and foremost a name. That name has to evaluate to a) content, b) history. In Git and Git-like immutable-commit systems this can trivially be implemented by a table mapping branch (and tag and...) names to commits. I.e., in any immutable-commit VCS branches are naturally pointers. The only real question is whether there should be additional semantics layered upon the pointer nature of branches. Indeed, there should be. In Git these are the basic rules: - branch names are updated when adding commits in a workspace that has that branch checked out - tag names are NOT updated when adding commits when adding commits in a workspace that has that tag checked out - local configuration can enforce a variety of rules via commit hooks - upstreams can enforce a variety of rules, such as fast-forward-only (no history rewriting) This gives users a great deal of flexibility, including the ability to ban history rewriting on published branches and to allow it on unpublished branches.

lakpan 3y ago

That’s not right. A branch is a single pointer to a single commit. Just open your .git folder. It’s then Git itself that follows that commit’s pointer to its parent(s). The branch, like the tag, is a single reference to a commit. Do this: $ cat .git/refs/heads/main

Buttons840 3y ago
It seems accurate enough to say the branch includes all the parents of the pointed to commit. It's a matter of definition, but both definitions are technically accurate. (Also, note the path you ask us to cat does not contain the word "branch". You refer to how things are stored to support your definition, but the way things are stored doesn't use the term "branch".)
Espressosaurus 3y ago
The question was "what do you think is the most natural way to think about it", not "how does git represent it".
- lakpan 3y ago
  What? If you’re looking for “the most natural” then you’ll find it in the name. You can’t “explain” branch by using a synonym. Plus that definition describes both tags and branches, how do you tell them apart? It’s clearly lacking. Actually that definition fits commits too. I’d rather use these: Branch: a pointer that advances Tag: a permanent pointer Commit/hash: an even more permanent pointer (because even a force can’t change it) that also describes the changes.
seba_dos1 3y ago
Technically, you're right. Practically however, it does make sense to implicitly dereference the branch you're talking about to the commit it points to. Asking "is this commit on that branch?" is semantically equivalent to "is this commit reachable from the commit that branch points to?". That said, it only makes sense to make such implicit mental shortcuts once you're already comfortable with git's data model. If you're not and you're still learning it, it's only going to confuse you.
- lakpan 3y ago
  To be honest, describing a branch the wrong way is only going to confuse people more. The “dots on the line” visualization is pretty clear: you can have any number of branches pointing to a specific dot/commit. How do you add “branches” without fundamentally breaking that concept? When you create a branch, you’re not copying the line, you’re just adding a pointer.

Buttons840 3y ago

Are you saying that the "natural way" you think about branches is as a DAG terminating at one point? Because that is true; that is accurate. Thus, I don't understand your original claim that branches work in an unintuitive way.

Espressosaurus 3y ago
A branch in Git is just the pointer to the tip of the DAG. The way I find it natural to think about is it's the entire DAG of commits. To put this in programming terms, a git branch is a pointer. I think of a branch as the value is the most natural way to think about it. This mismatch is what leads to endless tutorials on what git actually means when it uses its vocabulary.
- Buttons840 3y ago
  If I created my own git implementation with the exact same CLI, but under the hood I didn't use a "pointer", but instead used the "value", would this be more intuitive to you? One problem I'm trying to express with that question is: You say it's unintuitive, but when asked why you refer to a very low level technical detail. My suspicion is that people find git branches unintuitive, and thus they think something more intuitive must exist. They have vague ideas about what "more intuitive" might mean, usually it means "just do what I want in this one situation I'm currently facing". My theory is that, if pressed, nobody can fully define a behavior for branches that is more intuitive than the current git implementation.
  - Espressosaurus 3y ago
    Well, you're still using the same CLI which is part of the problem. Git's CLI reflects its patched-together-hacked-executable history. It shouldn't be controversial to say the porcelain can and should be much more straightforward to use. DVCS concepts like the DAG and where you want to apply diffs are complicated the first time around, but after you get the concepts it should be easy to use, not difficult. Mercurial's branches are a better match for how I've seen branches use in practice. Tags are essentially the same between both. Evolve's hidden commits make it easier to recover lost data than Git's reflog, though the underlying implementation not permitting garbage collection kind of sucks.

cryptonector 3y ago

> A branch is a DAG of commits terminating at one commit. [Pedantically] this includes orphaned branches. > They should have just called it a pointer if it's a pointer. A branch in every VCS is first and foremost a name. That name has to evaluate to a) content, b) history. In Git and Git-like immutable-commit systems this can trivially be implemented by a table mapping branch (and tag and...) names to commits. I.e., in any immutable-commit VCS branches are naturally pointers. The only real question is whether there should be additional semantics layered upon the pointer nature of branches. Indeed, there should be. In Git these are the basic rules: - branch names are updated when adding commits in a workspace that has that branch checked out - tag names are NOT updated when adding commits when adding commits in a workspace that has that tag checked out - local configuration can enforce a variety of rules via commit hooks - upstreams can enforce a variety of rules, such as fast-forward-only (no history rewriting) This gives users a great deal of flexibility, including the ability to ban history rewriting on published branches and to allow it on unpublished branches.