Object-oriented programming with flavors

Abstract

This paper describes Symbolics' newly redesigned object-oriented programming system, Flavors. Flavors encourages program modularity, eases the development of large, complex programs, and provides high efficiency at run time. Flavors is integrated into Lisp and the Symbolics program development environment. This paper describes the philosophy and some of the major characteristics of Symbolics' Flavors and shows how the above goals are addressed. Full details of Flavors are left to the programmers' manual, Reference Guide to Symbolics Common Lisp. (5)

Traits

“…This is similar to template-based mixins in C++, which were scientifically investigated and described by Notkin [1996b, 1996a] as well as by Smaragdakis andBatory [1998, 2000] only after mixins were proposed as a fundamental composition mechanism by Moon [1986] and later analyzed by Bracha and Cook [1990]. As noted by VanHilst [1996b], templates were previously used, for example in the C++ Standard Template Library (STL) [Musser and Saini 1996], for genericity (i.e., writing data structures such as collections that can be used in the context of different types), but not for role composition using inheritance.…”

“…A mixin is an abstract subclass specification that may be applied to various parent classes to extend them with the same set of features [Moon 1986;Bracha and Cook 1990;Mens and van Limberghen 1996;Flatt et al 1998]. Instead of defining SyncReadWrite as a class, it is defined as a mixin.…”

“…The shared features must either be forced into the common parent (where they do not belong), or they must be duplicated in the classes that should share them. To overcome this limitation, language designers have proposed various forms of multiple inheritance [Meyer 1988;Keene 1989;Stroustrup 1986], as well as other mechanisms, such as mixins [Moon 1986;Bracha and Cook 1990;Mens and van Limberghen 1996;Flatt et al 1998;Ancona et al 2000], that allow classes to be composed incrementally from sets of features.…”

“…Flavors [Cannon 1982;Moon 1986] were an early attempt to address these problems: Flavors are small, incomplete implementations of classes, that can be "mixed in" at arbitrary places in the class hierarchy. More sophisticated notions of mixins were subsequently developed by Bracha and Cook [1990], Mens and van Limberghen [1996], Flatt et al [1998], and Ancona et al [2000].…”

Relaxed MultiJava

“…It is useful to consider the methods in a Java program to be implicitly partitioned into a set of operations (sometimes referred to as generic functions [35,7,42]). Each operation is a collection of methods that have the same name and type signature.…”