In my computer science capstone project, we have a team of 5 working on various things for an Android app for Pokemon as a multiplayer game (Github). One or two people are working on implementing the "battle engine" for the Pokemon games (Generation I only). This feature has a lot going on. Initially we had a single issue with about 50 checkboxes of things to implement. I since split that into 12 separate issues.
All development on this battle engine is being done in a branch called match-api-integration. It's a long-term branch, because it could take us several sprints to fully implement it. To implement an engine-specific feature, we branch off of match-api-integration, do some work, submit a pull request and then merge back into match-api-integration when it's approved. However, we want the most up-to-date battle engine for several other feature branches to ensure that the integration is correct between UI and data components, for example.
Because this branch is long-lived, how should we get those added features into other feature branches? Having periodic merges into other feature branches worked on during the sprint to have the most up-to-date engine clutters them with merge match-api-intgration into whatever-feature messages. It's not a big deal, but cluttering nonetheless.
Is this the typical practice for such a branch, or is there some alternative that is more appropriate that we haven't thought of?
The proposed duplicate is asking about what frequency in which to merge feature branches into a main branch, either incomplete or complete. My question is asking about how to update feature branches with code from yet another feature branch that happens to be a long-term branch. The advice in the duplicate also does not apply to my scenario; "only merge stable code" – of course the code in the long-term branch is stable, but how to update several other branches which depend on it is a different question to the one proposed int he duplicate.
Best Answer
In general, if people are working on multiple branches, I think it's helpful to integrate back into the main branch as often as possible. If you have one "big" merge every few months (or even every few weeks) it can quickly become very painful and error-prone (especially if you're doing merges between multiple people).
I also strongly encourage regular re-baselining (i.e. having everyone merge from the Main branch to their local branches) to prevent the local branches from getting too far "out of sync" with the main branch.
Keep in mind that, even for very well-architected systems, it's highly unlikely that significant changes to other parts of the system will have no effect on your branch at all.