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Kotlin Lifetimes

All interfaces exposed via Kotlin expose a public API for freeing the Kotlin wrapper object in lieu of reliable finalizers. This is done by making the "base class" for all such generated objects implement the Disposable and AutoCloseable interfaces.

As such, these wrappers all implement a close() method, which must be explicitly called to ensure the associated Rust resources are reclaimed.

The best way to arrange for this to be called at the right time is beyond the scope of this document; you should consult the official documentation for AutoClosable, but one common pattern is the Kotlin use function.

Nested objects

We also need to consider what happens when objects are contained in other objects. The current situation is:

  • Dictionaries that contain interfaces implement AutoClosable with their close() method closing any contained interfaces.

  • Enums can't currently contain interfaces.

  • Lists/Maps don't implement AutoClosable; if you have a list/map of interfaces you need to close each one individually.