Fickle: Dynamic object re-classification.

Re-classification changes at run-time the class membership of an object while retaining its identity. We suggest language features for object re-classification, which could extend an imperative, typed, classbased, object-oriented language. We present our proposal through the language Fickle. The imperative features combined with the requirement for a static and safe type system provided the main challenges. We develop a type and effect system for Fickle and prove its soundness with respect to the operational semantics. In particular, even though objects may be re-classified across classes with different members, they will never attempt to access non-existing members.