Re: [RFC/PATCH] extend meaning of "--root" option to index comparisons

From: Jeff King <peff@peff.net>
Date: Sep 19, 2008, 17:39 UTC
Message-ID: <20080919173947.GA24541@sigill.intra.peff.net>
In-Reply-To: <3665a1a00809190954q2473e164u5d80d3653d238a27@mail.gmail.com>

On Fri, Sep 19, 2008 at 09:54:15AM -0700, Anatol Pomozov wrote:

> I dont see how does log.showroot or core.showroot affect 'git log'.
> man git-log says nothing, git-config only mentions that initial commit
> is "a big creation event".

Try this:

  mkdir repo && cd repo && git init
  echo content >file && git add file && git commit -m initial
  git show ;# you see initial as creation event
  git config log.showroot false
  git show ;# you see commit log, but no diff
  git show --root ;# same as log.showroot=true

where of course the same holds for log, as show uses the same display logic.

> But for me as for person that still actively works with Subversion it
> was quite surprising that I have error messages right after I created
> a fresh empty repo. I always thought that "Empty repo" -> "No history"
> -> "No log output"

I agree it is a bit nicer not to get an error in that situation. It is really a result of the way git thinks of history. It is not "no history" but rather "some history may or may not exist, but you have no valid pointer to any history".

However, I wonder if it might be possible to special-case the "branch yet to be born" case. That is, if HEAD points to a ref which does not exist, can we treat that specially. I suspect it may turn out to be a lot of work tracking down all of the spots in the code that would need to be special-cased, which may make it not worthwhile.

Show 6 quoted lines

> > Maybe it really is better to just force the caller to check the initial
> > commit condition. It's more work for them, but the semantics are simple
> > and unambiguous.
> 
> What is the best way to check that repo has valid HEAD? Check that
> file .git/HEAD exists?

No, HEAD will exist even in a just-created repo. But you can check whether HEAD points to a valid commit:

  git rev-parse --verify HEAD

-Peff