Re: [TopGit PATCH] tg-create.sh: Introduce --add option to add a dependency.

[Jan Nieuwenhuizen <janneke-list@xs4all.nl>]

On vr, 2008-08-15 at 10:25 -0500, Jonathan Nieder wrote:

Hi,

> 1) How should the tree of B' be determined?
> 2) What should the parents of B' be?
> 3) How should the tree of P' be determined from P, B, and B'?
> 4) What should the parents of P' be?

> So all this trouble is there when we try to come up with the topic 
> base
> for a new topic, as long as it is possible /in some way/ to weaken
> dependencies.

Which I have just been avoiding...  Thanks, that clarifies things for
me.

> or, if we make B a parent of B',
> 
> 	$ git checkout P
> 	$ git merge B'
> 
> which might be preferrable.

> I tried this out, and it seems here I was worrying needlessly.

Ok, good to know.

> > Ouch, I'm feeling so git-unitiated here; what is read-tree doing 
> > differently from merge?  Isn't here a -m missing?
> 
> Why?  We want to just blindly take the tree from P' and using it.  The
> point is to make setting the contents of the new branch tip and its
> parentage separate decisions.

Hmm, for one, "git read-tree -u SHA" does not work for me.

> > Removing or [re-]adding one dependency using this rebase-by-merging 
> > approch would take ~7 minutes on my machine.
> 
> Can you be more precise here?  What user action causes topgit to do
> so much work (adding one dependency to what topic)?  What other
> approach avoids all this work?

Good question, I was thinking a bit careless here.  Creating the master
topgit branch, which depends on ~300 single-topic topgit branches, like
so

    tg create t/master $(git branch | grep -vE '/|patched|pristine')

takes ~7 minutes; which does not really surprise me.

I realise now that if we make a strict *adding* of dependencies a
special case, we can just checkout our old B, and add (merge) the
additional dependencies on top of that.

However, when *removing* a dependency, I see no easy way to do that cheaply.

Greetings,
Janneke

-- 
Jan Nieuwenhuizen <janneke@gnu.org> | GNU LilyPond - The music typesetter
http://www.xs4all.nl/~jantien       | http://www.lilypond.org