Specifically "complex runtime state inspection (say, to support breaking reference cycles)". There's no safe way to walk the object graph to break reference cy

Specifically "complex runtime state inspection (say, to support breaking reference cycles)". There's no safe way to walk the object graph to break reference cycles, despite Apple implementing both ivar indirection (to solve the fragile base class problem), and implementing what should be self-describable block structures. Information such as whether a particular captured variable/ivar is a weak or strong reference would have been very simple and cheap to include in the runtime metadata, but was -- like many other things -- not included. In another comment in this thread I described the difference between Apple's runtime/language design and everyone else's: This sort of hackish minimalism is the polar opposite of the careful considered and long-term focused design that Microsoft (and even Sun) applied to the core of their platform. Compare the completeness (and longevity) of the JVM Virtual Machine specification to the ObjC runtime. Over roughly the same amount of time, Apple has had to introduce complete ABI-breaking fundamental changes of to their runtime to implement extremely basic language enhancements. In contract, the JVM specification has not, to my recollection, been broken once over the course of 20 years. Additions have always been forward-compatible.