Aliasing control with view-based typestate

Tracking the state of an object (in the sense of how a File can be in an Open or Closed state) is difficult not just because of the problem of managing state transitions but also due to the complexity introduced by aliasing. Unchecked duplication of object references makes local reasoning impossible by allowing situations where transitions can be triggered unexpectedly (for instance, passing aliased parameters to a method that expects unaliased parameters, or calling a method that has a side effect through an alias deeply nested in a data structure).