Decoupling in Object Orientation

In formal design, decoupling means to make the features of a formal system as independent as possible from each other. Decoupling tends to make the features semantically more primitive and the overall system more general. Quite opposite to decoupling, the tradition in object oriented refinement theories is to combine all features, such as specification, usage constraints, encapsulation and inheritance into a single formal construct, the class. We propose a decoupled formalization of object orientation, in which all those features are introduced independently from the class construct and from each other. Even though each of the features is significantly simpler than its standard counterparts, the overall system is more general: standard class-based object orientation is shown to be a special case of our system.