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Comment by adityaathalye | Hacker News Reader

Yes, I think it's a common case of getting the fact right, viz. branch == just a ref (true), but the understanding wrong, viz. ref == commit (false).

A commit is an immutable object. Whereas a ref is a pointer, literally a place on disk (a regular file) that holds an address (plaintext SHA) to the latest point in a logical chain of commits.

Meta remark:

This is also what makes it ok to delete a branch after it is "done", and why it is ok to merge a standard working branch (like "develop") repeatedly into a target branch (like release/master/main/trunk).

The semantic / meaning of a branch is transient. It is mutable conceptually and literally.

edit: formatting

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Sort of an aside, I find it funny that the reflog is named that and not commitlog. With this mental model when you look at the reflog you usually want to get back an immutable commit because you've lost the ref. I know it displays the commits and the refs, but does anyone actually look at the reflog and checkout HEAD@{6} or do they use the commit sha?

Yes, I've done that, because the reflog keeps more than just commits. It also keeps checkouts, merges, steps in rebasing, etc. So I've checked out a HEAD@ ref, when I made a mistake in merging or rebasing.

reflog it a tool to show you the history of a given ref - if you don't give it any, it defaults to HEAD. It seems to me like "reflog" is the perfect name for it and I don't see how "commitlog" would be relevant to what it does.

Did you confuse "refs" (references) with "revs" (revisions)?

No, I was going based off the mental model I replied to:

> A commit is an immutable object. Whereas a ref is a pointer, literally a place on disk (a regular file) that holds an address (plaintext SHA) to the latest point in a logical chain of commits.

Reflog shows you the immutable commit SHA and the HEAD@{N} ref. I've only ever used it to get back to a commit I've lost, never by ref, so to me it's a commitlog.

HEAD is a ref just like any other. What you're looking at after typing `git reflog` is the history of things HEAD has pointed to - it's HEAD's log. Refs don't necessarily have to point to commits, they can point to other objects too.

HEAD@{<N>} is not a ref - it's a rev in <ref>@{<N>} form that means "N positions back in ref's history" (see `man gitrevisions` for more rev forms).

> never by ref

When you look at reflog's output, you've already dereferenced these commits by the given ref and its history.

Try `git reflog <branchname>`.

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