Capability Safe Reflection for the Wyvern Language

Reflection allows a program to examine and even modify itself, but its power can also lead to violations of encapsulation and even security vulnerabilities. The Wyvern language leverages static types for encapsulation and provides security through an object capability model. We present a design for reflection in Wyvern which respects capability safety and type-based encapsulation. This is accomplished through a mirror-based design, with the addition of a mechanism to constrain the visible type of a reflected object. In this way, we ensure that the programmer cannot use reflection to violate basic encapsulation and security guarantees.