Git's Staging Index is for the Real World

I love git. One thing I love most about it is the staging index:

With most other version control systems, there’s 2 places to store data: your working copy (the folders/files that you’re currently using) and the datastore (where the version control decides how to pack and store your changes). In Git there’s a third option: the staging area (or index). It’s basically a loading dock where you get to determine what changes get shipped away.

This is a unique idea to git. There are two primary arguments I’ve heard against it:

  1. It’s needlessly complicated.
  2. You should never be checking in a state you haven’t tested.

While it’s true that you now have an additional step, I hardly think it’s a needless one; this complaint seems to come mostly from Subversion users who are trying to alias svn commit to git add . && git commit && git pull && git push.

The second is quite a valid argument. It’s not generally a good idea to pull only bits and pieces of what you’ve tested into your commit; it’s the same result as when you forget to add a file that you created (and your changes rely upon). I feel it’s quite necessary to allow this, though, because

I live in the real world.

I know, it’s crazy, but sometimes I have to deal with things that theoretically should never happen if we were completely following Foobar Programming, but the state of the world right now is that it’s broken and I have to fix it and our customers are calling and my boss is asking me why it isn’t done yet and I just don’t feel this is the right time for a major refactoring of the system.

Here’s a real example: at work, we have a daemon system we wrote to process queue requests. On our development machine, the workers source their code from one checkout of the code. This means that any developer wanting to test changes in the queue-processing system has to make changes to that one directory. This gets to be a bit annoying when multiple people have to do this simultaneously.

Now, yes, this needs to be changed. But I have 60 other tickets on me at the moment, and I can’t get them all done right now, so I have to deal with the situation for a bit longer. And if I was using Subversion, I’d have to remove this other person’s changes to this file, save the file, commit it, then revert my removal, whereas right now all I have to do is run git add -p.

BTW, I can actually test my changes separate from theirs, now: I just have to run git stash --keep-index, run my tests, git stash pop and continue on my way.

Here’s another reason I commonly use git add -p: differing test and production environments. There are a number of debug constants we’ve got set to true in development, but really, really don’t want to have that way in production. There are also changes that are necessary simply because the development environment isn’t set up completely the same as production. Should they be the same? Sure, but that will require me to rebuild our entire development infrastructure, and that ain’t happening by Tuesday.

tldr: staging index helps me get shit done.