A dynamic topology processor for a radial distribution system using object-oriented methodology is presented. The potential of object-oriented design patterns is also employed to obtain an extendible design. The decorator design pattern is used to separate the topology-based attributes from the attributes representing physical characteristics of the objects. Using decorator pattern, responsibilities can be dynamically attached to or removed from the objects. The state design pattern is used to model the switching states of the tie and sectionalising switches. The proposed topology-processor algorithm is a local updating technique, hence less time consuming. The proposed algorithm has been implemented in C++ and tested with a modified 69-bus system. It has been found that the average CPU time required to modify the links between the objects following a switching operation is only 0.4ms.