Changes in MATSim from the Code Sprint 2025
In the last week of March 2025, 14 MATSim developers from various institutes and companies came together in Berlin for a week of discussions and coding. At this week-long event, the following decisions and changes were made:
- Renaming the default git-branch to
main. For a few years now, the git-community usesmainas the name of the default branch in new repositories. We now follow this convention and have renamed the previousmasterbranch tomain. - Squashing for Pull Requests. When merging changes from contributors, the branches were merged into the main branch using a merge commit, keeping all individual commits of the merged branch. This lead to sometimes very complex and nested commit histories, making it harder to understand what actually changed. We now decided to use sqashing by default when merging PRs. This will result in a single commit for all the changes being merged, which will result in a much shorter and hopefully cleaner commit history of our large project.
- Use Conventional Commit messages. For the PRs, we now suggest to use the so-called conventional commit message format. Together with the squashed commits, we hope to be able to provide the often-requested changelog for new releases in the future.
- Better support forum. For the past few years, we used GitHub’s issue tracker to answer support requests. As the interaction capabilities for the issues were limited for a support forum, we now decided to start using GitHub Discussions instead. You can reach the new support forum using the stable URL www.matsim.org/faq.
- Remove deprecated and outdated code. We removed several methods and classes that were
marked as deprecated for a few years already in order to clean up our code base. We plan
to do this more often in the future, so if you use MATSim to write some code, please
adapt your code regularly if you use deprecated constructs. In addition, outdated and/or
unmaintained packages like
jdeqsimandlaneswere or will be removed.