An Extension Mechanism for the Java Language

This thesis presents the design and implementation of an extensible dialect of the Java language, named OpenJava. Although the Java language is well polished and dedicated to cover applications of a wide range of computational domain, it still lacks some mechanisms necessary for typical kinds of applications. Our OpenJava enables programmers to extend the Java language and implement such mechanisms on demand. It is an advanced macro processor based on the technique called compile-time re ection. In this thesis, rst, the problems of traditional compile-time re ection systems are pointed out; with those systems, it is di cult to write meta-level programs. Those re ective systems are not suitable for macro processing which are non-local, scattered, and spreaded in source programs, although such macro processing are typical in object-oriented languages. Also, those re ective systems do not provide su cient supports of using di erent extensions together. Then this thesis proposes a new compile-time re ection system for OpenJava. With OpenJava, translation of source code is indirectly performed through an abstract data structure called metaobjects. This data structure gives meta programmers an intuitive view in object orientation. Meta programmers in OpenJava can describe extensions of the base Java language more intuitively and safely than in traditional re ective systems. Finally, several examples are presented to show the good usability of OpenJava.