Extensibility in the Oberon System

We show how an object-oriented system-and in particular the Oberon System-can be used to write software that is extensible by end users even while the software is running. Extensibility instead of completeness may be a way out of the unpleasant situation in software industry where applications still tend to become bigger every year. Oberon is both an object-oriented programming language and an operating system with new concepts such as commands and dynamic loading. The language and the system make up an environment that is similar to Smalltalk in its flexibility but offers static type-checking and is much more efficient.