USENIX Technical Program - Abstract - COOTS 99
Filters as a Language Support for Design Patterns in Object-Oriented Scripting Languages
Gustaf Neumann and Uwe Zdun, University of Essen, Germany
Scripting languages are designed for glueing software
components together. Such languages provide features like dynamic
extensibility and dynamic typing with automatic conversion that make
them well suited for rapid application development. Although these
features entail runtime penalties, modern CPUs are fast enough to
execute even large applications in scripting languages efficiently.
Large applications typically entail complex program structures.
Object-orientation offers the means to solve some of the problems
caused by this complexity, but focuses only on entities up to the
size of a single class.
The object-oriented design community proposes design patterns as a
solution for complex interactions that are poorly supported by
current object-oriented programming languages. In order to use
patterns in an application, their implementation has to be scattered
over several classes. This fact makes patterns hard to locate in the
actual code and complicates their maintenance in an application.
This paper presents a general approach to combine the ideas of
scripting and object-orientation in a way that preserves the
benefits of both of them. It describes the object-oriented scripting
language XOTCL (Extended OTCL), which is equipped with
several language functionalities that help in the implementation of
We introduce the filter approach which provides a novel, intuitive,
and powerful language support for the instantiation of large program
structures like design patterns.
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