On Fri, 2 Feb 2007, Andy Parkins wrote:
> Forgetting about detached heads for the moment,
That is not the way to go about it. You cannot start forgetting about
detached heads and come back to it afterwards like an afterthought.
> imagine that yesterday I did
> lots of bouncing around on branches, around 1300 (although I wouldn't
> remember the exact time). Oh look, it's about 1300 now. What then is
> HEAD@{yesterday} going to tell me? What will it tell me one minute from now?
> It would be the most confusing operation in the world; I'd have to remember
> which branch I had checked out and what time I checked it out.
The exact same argument could be said if you did 1300 operations on a
single branch, say master. What would master@{yesterday} tell you?
What will it tell you one minute from now? Now suppose that you have
only one branch and therefore HEAD reflog would be a duplicate of master
reflog.
Answer: it would carry the same kind of confusion as your example above.
> I really don't want to be able to answer the question what branch did I have
> checked out 15 minutes ago. I do want to ask where was my current branch 15
> minutes ago.
Then simply use @{15 minutes ago}. You'll even save yourself some
typing! It is not like if you have to type HEAD for most operations
anyway since HEAD is the likely default in most cases. So you may even
forget that the HEAD entity exists and be just fine.
But HEAD is still a moving pointer and we might want to know that it
switched from one branch to another at some point. And the only way for
that to be sensible is by having a separate reflog for HEAD that is the
exact log of every operations you perform regardless of the actual
branch you might be on.
> Then of course, it's perfectly reasonable to treat the detached HEAD as
> meaning that the symref HEAD was pointing at a kind of virtual branch - this
> is a branch that isn't in the refs directory but is reflogged. Other than
> that it's no different from any other branch.
>
> Any notation would do I think, @{} is as good as any other. In fact, if we
> used the name "unnamed branch" instead of "detached head", the notation @{}
> is perfect. (Actually I think unnamed branch is a much better term than
> detached HEAD, because HEAD is never detached - it must point at something)
HEAD _does_ get detached. It becomes loose in the air. It doesn't drag
any
branch
pointer with it. And everything you do on top of a detached HEAD will
be forgotten as soon as you leave it (and the eventual reflog for HEAD
expires) if you don't attach it somehow with a tag or a new branch.
There is no notion of a virtual branch at all, not technically, not
conceptually either.
Nicolas
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