Morphable objects in Smalltalk

In distributed applications, objects can live independently of any application that interacts with them. For this reason, it becomes difficult to modify their structure, e.g. their implementation and/or interface signature. In order to support the modification of objects, it is necessary to decouple clients from potentially morphable objects by inserting an immorphable intermediary (known as the encapsulator). The encapsulator intercepts calls to the morphable object's methods, enabling the encapsulator to redirect the call, transform the call, or perform pre- or post-processing on the call. A prototype of morphable objects has been developed in Smalltalk (using VisualWorks 2.5.2). The techniques for implementing encapsulators and mutating the objects in Smalltalk are described.