Scalable extensibility via nested inheritance

Abstract

Inheritance is a useful mechanism for factoring and reusing code. However, it has limitations for building extensible systems. We describe nested inheritance, a mechanism that addresses some of the limitations of ordinary inheritance and other code reuse mechanisms. Using our experience with an extensible compiler framework, we show how nested inheritance can be used to construct highly extensible software frameworks. The essential aspects of nested inheritance are formalized in a simple object-oriented language with an operational semantics and type system. The type system of this language is sound, so no run-time type checking is required to implement it and no run-time type errors can occur. We describe our implementation of nested inheritance as an unobtrusive extension of the Java language, called Jx. Our prototype implementation translates Jx code to ordinary Java code, without duplicating inherited code.

Type-Checking Software Product Lines - A Formal Approach

“…For the same reasons, we chose FJ over other Java calculi like Classic Java [13], Java light [25], or Java s [12]. Besides many other examples, FJ was used to formally discuss an extension of Java with generics [17], to formally discuss inner classes [18], and to reason about new composition techniques like nested inheritance [26].…”

Lightweight scalable components

“…Considerable research efforts including family polymorphism have been recently devoted to solve this problem [8,12,21,30,18,5,23]. In family polymorphism, like virtual methods, a reference to a nested class member is resolved at run-time, thus the meaning of mutual references to class names will change when a subclass of the enclosing class is derived and those member classes are inherited.…”

“…This restriction becomes a serious problem when we consider the collaboration based implementation such as family polymorphism and other approaches [8,12,21,30,18,5,23]. Family polymorphism satisfies the important requirement of scalability; i.e., in family polymorphism, each set of mutually recursive classes, namely a family, may be safely extended without modification of the existing source code.…”

Pointcuts, advice, refinements, and collaborations: similarities, differences, and synergies

“…A refinement introduces new members to this class and/or extends existing methods by method overriding There are several techniques for implementing class refinements, e.g., mixins [10,14], classboxes [9], virtual classes [23], or nested inheritance [27].…”