One of the great things about the Git version-control system is the ability to incrementally commit your changes on a private branch to keep a step-by-step record of your thought and writing process on a fix or a feature, and then merge the completed work onto your main [or public] branch after your feature or fix is all done and tested. By keeping an incremental log of your changes — rather than just committing one giant set of code with changes to 30 files — it becomes much easier to know why a certain line was changed in the future when bugs are discovered with it.
One thing that often happens to me though, is that I work for about a half hour to an hour trying to get a new piece of code working and in the process make several sets of changes to one file that are only loosely related.
Let’s say that I am fixing a bug in my ‘MediaLibrary’ class and while doing so notice some some spelling mistakes in some comments that I fix. Now my one file has two changes my bug fix, and the spelling fix. Rather than committing both changes together with one comment describing both changes, I can highlight one of the changes in git-gui and select the “Stage Hunk for Commit” option.
With that one hunk staged I can now commit with a message applicable to that change. Other changes can then be staged and committed with their own messages resulting in a very understandable history of changes.
“Stage Hunk for Commit” can also be used to commit important changes while not including debugging lines inserted in your code.
