Mechanism for decoupling consumers and providers of behaviours

Sometimes we find ourselves passing around context information about how to perform a certain operation (e.g. check if an oop is alive, logging or tracing, etc). Sometimes such behaviours are provided globally by a GC, and sometimes only in scopes known by the GC. Sometimes it is even accessed from mutators.

It would be great to have a general mechanism for decoupling how behaviours are provided, from the code that uses them.