Source Control to Major Tom

To a coder, nothing is more precious than his code. Source control management (SCM) is all about keeping your code safe. Not against disk failures, so much as against bad edits ("what was I thinking!" !). It's also a good place to stash some forms of comments (not what the code is doing, but why it was written). Mixing this into the code can be distracting. SCM also provides a nice log of when features were added ("it's been two years!?").

I had my first encounter with source control as an intern at Intel. Our files were under CVS (concurrent versioning system), with some binary files directly managed with RCS (CVS started as a wrapper around RCS - all those funny ,v files).

CVS is ancient (1990), and works really well. You have to be careful with merging conflicts, tagging takes forever, and branching is so confusing no one ever used it. You have to stretch the meaning of "really well"...

Eventually (about ten years ago), some people decided to improve on CVS. That project is called Subversion (svn). I didn't use Subversion until about two years ago. SVN is a big improvement over CVS. The main thing - being able to do a diff against a network repo while not connected to the network. Also, SVN is much better with merging. Tags and branches use the same mechanism, which is cheap and easy. Very nice.

I used CVS professionally until about 2003. That was when I was exposed to the Great SCM Wars - between minions of Darcs, and keepers of BitKeeper. I will have to rant about them sometime. Suffice to say, that no man has ever fought with them and lived! The bones of many projects lie strewn about their lairs. So if you do doubt you courage, come no further. For death awaits you all; with nasty, big, pointy teeth.

Ok, so I still use CVS for my personal projects. I would like to switch over to something new, probably "distributed". There are three alternatives:

1. Git - created by none other than Linus of Linux fame. He too was a victim of BitKeeper, so he is familiar with pain. He is a really smart guy who churns out quality software at a prodigious rate. He also tends to be a little quirky, and he is (ultimately) writing software for himself, so there is no guarantee I will get the same returns...
2. Mercurial (hg) - apparently started about the same time as Git (2005), for the same reason (holding the Linux kernel tree)
3. Bazaar - the newbie in this line up (2007, and new is bad, like in compilers - new means buggy and untested). But, I am willing to give it a shot.

I had previously compared these three and decided on a winner. Sadly, I can no longer remember which one I picked. And things have changed some since then. At the time, Git was basically Linux only (there was a Windows hack by some guy who was trying madly to keep up). Now, I can get Git as a Cygwin package.

I will have to go through again and compare. I don't think SVN is in the running, as it does not have a distributed model. I like the distributed model, because it allows me to push code from one machine to another without having to worry about which one is the "master".