Re: best git practices, was Re: Git User's Survey 2007 unfinished summary continued

Steffen Prohaska <prohaska@xxxxxx> · Thu, 25 Oct 2007 08:02:57 +0200

On Oct 25, 2007, at 1:28 AM, Johannes Schindelin wrote:

On Thu, 25 Oct 2007, Steffen Prohaska wrote:

On Oct 25, 2007, at 12:14 AM, Johannes Schindelin wrote:

But I think I have to drive my message home again: if what you  
desire
becomes reality, you take away the clear distinction between  
local and
remote branches.  In fact, those branches are neither local (because
the next pull will automatically update them with remote changes,  
but
_only_ if they fast-forward) nor remote (because you plan to work on
them locally).

Exactly, because I do not work on those branches alone. These are
_shared_ branches. I can work on such a branch with a group of
developers. I'm willing to accept this bit of chaos.

It is not just a chaos.  I see a serious problem here.  On _your_
computer, you do _not_ have a shared branch.  Which is visible  
_even_ in
your modified work flow when you have unpushed changes.

So your desired illusion that your local branches are anything but  
local
branches will never be perfect enough.

Ok, there is not a fundamental difference between local branches
that automatically merge from remotes and local branches that
are purely local and _never_ merge anything automatically. Both
are only local branches.

But these two types of branches already behave differently when
I call "git pull". There is already some kind of "illusion"
that some local branches are more tightly connected to remote
branches than others.

"git pull" could help to make the illusion even better. The
illusion would be better if it was easier to keep the heads
of the local branches near to the heads of branches they
automatically merge from, as long as this is easily possible.

Your rebase workflow is not possible if more than one dev wants to  
work
on the topic branch together.

Why not?  I do it all the time.  CVS users do it all the time, for  
that
matter.

You're right. You can rebase your local changes on top of the new
shared remote head. And this is probably the best thing you can do
to get a clean history. Maybe it should be easier.

So, do I understand correctly, what you propose is:
- never merge but only rebase
- Due to lacking support for this in "git pull", never use
  git pull when working with shared branches but instead _always_ use
  "git fetch; git rebase origin/<branch_I'm_on>".

So you say that one of the first messages in "git for CVS users",
"The equivalent of cvs update is git pull origin" [1], is wrong.
I don't think I'm able to sell your proposed workflow with the current
documentation. But maybe I try if I'm absolutely convinced that it
is superior.

[1] http://www.kernel.org/pub/software/scm/git/docs/cvs-migration.html

But here is a proposal which should make you and your developers
happy, _and_ should be even easier to explain:

Work with topic branches.  And when you're done, delete them.

Again, if you want to share the topic branch the situation gets
more complex.

Hardly so.  In my proposed solution to your problem, there is nothing
which prevents you from working off of another branch than "master".

Well if you have several local branches checked out that are
shared with others you run into the "git push" problem again ...
(see below at git push origin master).

So the beginning of the day could look like this:

	git fetch
	git checkout -b todays-topic origin/master

	[hack hack hack]
	[test test test]
	[debug debug debug]
	[occasionally commit]
	[occasionally git rebase -i origin/master]

and the end of the topic

	git branch -M master

Isn't this a bit dangerous? It forces to overwrite master
no matter what's on it. You don't see diffstats nor a fast
forward message that confirms what you're doing.

	git push origin master

I'd like to see "git push" here. But to make this work without
error you'd need to _delete_ master after you pushed. Otherwise
it could happen that you later work on a different shared
branch and "git push" would complain about master. "git push"
would recommend to do a "git pull" and we're back where the
discussion started.

Or do you propose to delete master at this point? That is do
you propose to _never_ have remote branches checked out locally.
Except for a very short period when you do

    git branch -m <shared_branch>
    git push origin <shared_branch>
    git checkout do-not-work-here
    git branch -D <shared_branch>

If you should not be ready to push by the end of the day, no need to
worry.  Just stay on that topic branch, and before pushing, do

	git fetch
	git rebase origin/master

In _every_ case where I explained git, I found that people  
appreciated the
two-step procedures (like you will find in the examples I showed you
above): one git command to work locally, and one to push/fetch to/ 
from
origin.

Maybe. I know git quite well now and in a shared workflow "git pull"
with auto-fast-forward would help me. I often need to run "for each
local branch: git checkout ; git merge" to get rid of the errors
reported by "git push".

The problem I see here: you know git quite well.  Others don't, and  
will
be mightily confused why pull updates local branches sometimes, and
sometimes not.

But it already happens now. "git pull" sometimes merges a
remote branch (--track) and sometimes it reports an error that
is fails to do so (--no-track). It would only do more work
automatically in the future and report appropriate warnings
or errors if it runs into a problem.

	Steffen
-
To unsubscribe from this list: send the line "unsubscribe git" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at  http://vger.kernel.org/majordomo-info.html