Here at Mozilla, a bunch of webdevs use git svn instead of plain Subversion to interact with our svn repositories — mostly because of in-place branching, better merging, and all these things that make a dev’s life happier.

As you probably know when reading this article, you push all uncommitted changes to the remote svn repository by typing git svn dcommit. This will take your last, say, five commits, push them to SVN, and mark them locally as committed. But what if you only want to dcommit some of your changes?

(If you don’t need explanations, jump straight to the summary).

Step 1 (optional): Reorder commits

I am not going to go into a lot of detail on interactive rebasing (git rebase -i), but to start off, make sure your commits are ordered, so that the ones you do want to commit to SVN are before the ones you do not want to push up-stream for now. Example: If in the following history, you want to commit all changes but a023fea, you want to rebase your commits so a023fea is last:

In git rebase -i HEAD~4, change…

pick 07c26c5 some de L10n
pick a023fea adding free-text messages to localizer dashboards
pick 8597f47 adding featured collections as l10n category
pick 19f3df3 making existing localizer pages work with amo2009 layout

… to…

pick 07c26c5 some de L10n
pick 8597f47 adding featured collections as l10n category
pick 19f3df3 making existing localizer pages work with amo2009 layout
pick a023fea adding free-text messages to localizer dashboards

Make sure to resolve any merging problems that might occur due to the reordering.

Step 2: Step in between commits

To only push the desired commits to svn, execute another git rebase -i and mark the last desired commit for editing (by changing pick to edit):

pick 07c26c5 some de L10n
pick 8597f47 adding featured collections as l10n category
edit 19f3df3 making existing localizer pages work with amo2009 layout
pick a023fea adding free-text messages to localizer dashboards

When exiting the editor, git will drop you off after the marked commit, but before the one you don’t want, as a quick look at git log can tell you.

Step 3: dcommit desired changes

After making sure this is really what you want, just execute git svn dcommit as usual and watch git push all desired changes to SVN, while omitting the rest.

Step 4: Fast-forward to HEAD

When the dcommit is done, remember we are still in the middle of a rebase, so just run git rebase --continue to fast-forward to the HEAD of your branch. Again, a quick look at git log can reassure you that only the changes you wanted to have been pushed to SVN.

Success!

Summary: Quick cheat sheet

Here’s a quick cheat sheet for you (and me) to come back to in case you forget:

• Reorder commits (git rebase -i HEAD~4) so that the undesired ones are after the ones you want to push
• In your commit history, jump right after the last wanted commit by marking it for editing in git rebase -i
• git svn dcommit
• git rebase --continue

Here’s another, beautiful specimen in my little collection of what I have called “fail pets” for awhile now: Github.

I wonder if their pink fail-unicorn is somehow related to the similarly colored (but less angry) Django Pony. A distant relative, maybe — especially since the “original” Django pony was, in fact, a unicorn.

(Before someone is urged to remind me, yes, to my knowledge, github is written in ruby, not Python/Django.)

If you are an American expat, or something along those lines, and are in the mood for some Christmas music, you might have already taken a look at “iTunes Radio”, and had a hard time to find any, because even the ones carrying Christmas in their name don’t quite cut it…

A good trick is to go for the Adult Contemporary section:

… and select a soft rock station, such as “Soft Rock from St. Louis”, which is what we listened to today. These stations have a tendency to switch to Christmas music during the season, and should serve all your Christmas music needs, even if there’s no way you can receive it on your local radio tuner.

Have fun, and happy holidays.

When skimming through my pending Mac OS X upgrades this morning I noticed one saying:

This update eliminates the noise made by the optical disk drive during system startup and wake from sleep on MacBook computers.

Wow. As long as I’ve been using a Mac, the sweep-sweep noise has been characteristical for a Mac startup sound, reminiscent of the floppy drive seek sound computers made when they still came with floppy drives (yes, dear children, I am that old).

I wonder what this was for in the first place. Maybe to find out reliably if there is a disc in the drive already? <crystal ball>Possibly, the operating system did not check again and just relied on the hardware status flag being set correctly on startup, and if it was wrong, evil things could happen?</crystal ball> And now, almost suddenly, the Mac engineers found out that it is unnecessary altogether? The wonders of Snow Leopard.

What comes next? Removing the gong on boot to avoid Mac-obsessed college kids from making fools of themselves during lectures?