Using dynamic mixins to implement design patterns

Design patterns are used as a means of documenting solutions to commonly occurring problems. In this work, we focus on object-oriented patterns that require object extension. Typically, the implementation of such patterns is done using object composition. Dynamic mixin composition is proposed as a viable alternative in this paper. The issues of safety and reuse are considered during the comparison of the two approaches. A new mixin language is defined to illustrate the benefits of mixin composition. Then, a survey of sample GOF pattern implementations using both approaches is critiqued and finally some patterns specifically designed to address the shortcomings of object composition are critically reviewed.