Source code branching is one of the most contentious activity that you can engage in a software company. For some reason that’s eluding me, I keep hearing the same arguments over and over again about why we should not use branches, about how branching is hard. It’s not, neither conceptually, nor practically, it simply requires to be methodical and to overcome a visceral fear of the *Merge*. It works more or less with all current tools, with CVS probably the hardest to deal with and the last batch of distributed source control, the easiest.
One of the primary problems that Feature Crews address is the difficulty of maintaining the integrity of very large code bases under development (imagine 1000 developers coding against a 10,000,000 line system). FC poses the problem as the tension between a) keeping the main branch as current as possible, and b) keeping the main branch as robust as possible. The FC solution is to make features an atomic transaction. A feature is either 0% complete or 100% complete, and a feature is not 100% complete until it can be demonstrated that it satisfies the same quality criteria as the rest of the main branch.
Here’s an excerpt from Lean Software Engineering. FC in this context means “feature crew”.
“Features-in-process are not allowed on the main branch. The FC alternative is branch-by-feature. A crew takes a branch when it takes possession of the feature kanban. The crew is responsible for forward-integrating any changes that are checked into main while their feature is in process. That is, if another crew integrates and breaks your feature-in-process, it’s your responsibility, not theirs. When your feature is finally complete AND you have integrated with all changes on main AND you pass all of the quality gates, THEN you can reverse integrate your feature into the main branch, and everybody else will have to forward integrate your changes.”
Here it is: use branches extensively, merge back and forth. It takes some time, a bit of practice, but it puts to rest these endless discussions about whether we should branch, when and what for.
