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Design Patterns Overview - Factory

No software design patterns overview can be complete without describing the Factory pattern. I would say this is one of the most commonly used patterns. Let's get right to the UML diagram.


As can be seen an interface, Creator, is defined for creating a Product, but it is the ConcreteCreator that decides which subclass of Product to instantiate.
From the client you instantiate the ConcreteCreator and use that to create the products. It is the resonsibility of the ConcreteCreator to see to it that the product is created correctly. This adds a nice level of abstraction since any changes to how the ConcreteProduct is created only needs to be reflected in the ConcreteCreator. The users of the product does not need to change their implementation.

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