Ergonomic, hermetic, user-friendly software build system for Python, Go, Java, Kotlin, Protobuf, Scala, Shell. Pants lets you fearlessly scale up your codebase!

Pants

does `Subsystem` work the same way in v1 vs v2?

close, but not exactly the same. in v1 a singleton in stashed on the class itself.

in v2, you get an instance via a declared dependency, and the engine will make it a singleton via its own memoization

does a `Subsystem` subclass that's already being used in the v1 engine need to be changed so that v2 rules can use it?

no, just needs an `optionable_rule` registered