Creational Design Patterns |
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Creational Design Patterns
According to the GoF [4] a creational pattern "abstracts the instantiation process" (p.81). Essentially they "help make a system indepdendant of how its objects are created, composed and represented". There are essentially two different sorts of creational design patterns: The first type are class creational patterns which will use inheritance to vary what sort of class is instantiated when creating an object. The other type are the object creational patterns, wherein one uses delegation to determine the outcome of the instantiation process. When should one use creational design patterns? There is no single, hard and fast answer to that - however a heuristic can be that they apply to situations where one is building increasingly complex objects, variations of objects or composite objects - wherein one does not wish to tangle the logic of creating the various objects with the executional business logic. In this section we will be investigating a selection of creational design patterns, some of them stem from the "bible" of GoF [4], and some stem from other literature. Others again are variations on established patterns wherein new techniques have been utilized; for example reflection. The following creational design patterns have been implemented and discussed:
Factory - class creational
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copyright Paul Austrem (c) 2007