[Dicussion] How much backwards compatibility do we support?

[paulheinr]

Kai brought this up in MATSim advanced. One of the main reasons, why scientific (open source) software is able to compete with commercial software is that it doesn't have the business constraints like having a big support infrastructure (like high documentation coverage -- "code is documentation" -- or long backwards compatibility).

There are some questions regarding this topic (tbc):

• Which parts of the code are so important that we maintain backwards compatibility?
  • e.g. external (input files like config, plans, network) vs. internal API (public/private guice modules)
• Isn't backwards compatibility also for us a nice and important (?) feature? Code from older projects might break much earlier.
• Are there explicit examples where backwards compatibility make the code worse and our life harder while maintaining?
  • Make accessEgressModeToLink the default AccessEgressType for Routing and delete NetworkRoutingModule #3354