Metaclasses and Reflection in Smalltalk

TL;DR

This paper reviews Smalltalk's reflective features and extends them to support customizable inheritance strategies, especially in the context of multiple inheritance, which was previously limited.

Contribution

It introduces a novel approach to extend Smalltalk's reflection to enable programmer-defined inheritance strategies for multiple inheritance.

Findings

Extended Smalltalk reflection to support custom inheritance strategies

Analyzed multiple inheritance options and their implications

Proposed a language model with flexible inheritance control

Abstract

Many Object Oriented Programming Languages provide reflective features which may be used to control the interpretive mechanism of the language. Often these features are defined with respect to a golden braid consisting of objects classes and meta-classes. This report reviews the Smalltalk golden braid and generalize it for multiple inheritance leading to choices between many different inheritance strategies. The reflective features of Smalltalk cannot affect the basic mechanisms of inheritance and so an arbitrary choice must be made for multiple inheritance. A language is described in which the reflective features of Smalltalk are extended so as to allow programmer defined inheritance strategies.