Re: Re: Re: Add "clone" support to lntree

From: Petr Baudis <pasky@ucw.cz>
Date: Apr 16, 2005, 11:39 UTC
Message-ID: <20050416113955.GB14326@pasky.ji.cz>
In-Reply-To: <Pine.LNX.4.58.0504152014330.7211@ppc970.osdl.org>

Dear diary, on Sat, Apr 16, 2005 at 05:16:12AM CEST, I got a letter where Linus Torvalds <torvalds@osdl.org> told me that...

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> On Sat, 16 Apr 2005, Petr Baudis wrote:
> > 
> > I'm wondering, whether each tree should be fixed to a certain branch.
> 
> I'm wondering why you talk about "branches" at all.
> 
> No such thing should exist. There are no branches. There are just 
> repositories. You can track somebody elses repository, but you should 
> track it by location, not by any "branch name".
> 
> And you track it by just merging it.
> 
> Yeah, we don't have really usable merges yet, but..

First, this "level" of branches concerns multiple working directories tied to a single repository. It seems like a sensible thing to do; and you agreed with it too (IIRC). And when you do that, git-pasky just saves some work for you. For git-pasky, branch is really just a symbolic name for a commit ID, which gets updated every time you commit in some repository. Nothing more.

So the whole point of this is to have a symbolic name for some other working directory. When you want to merge, you don't need to go over to the other directory, do commit-id, cut'n'paste, and feed that to git merge. You just do

		git merge myotherbranch

Now, about remote repositories. When you pull a remote repository, that does not mean it has to be immediately merged somewhere. It is very useful to have another branch you do *not* want to merge, but you want to do diffs to it, or even check it out / export it later to some separate directory. Again, the "branch" is just a symbolic name for the head commit ID of what you pulled, and the pointer gets updated every time you pull again - that's the whole point of it.

The last concept are "tracking" working directories. If you pull the tracked branch to this directory, it also automerges it. This is useful when you have a single canonical branch for this directory, which it should always mirror. That would be the case e.g. for the gazillions of Linux users who would like to just have the latest bleeding kernel of your, and they expect to use git just like a "different CVS". Basically, they will just do

		git pull

instead of

		cvs update

:-).

-- 
				Petr "Pasky" Baudis
Stuff: http://pasky.or.cz/
C++: an octopus made by nailing extra legs onto a dog. -- Steve Taylor