02 FactoryMethod

1. Intent:

2. Defines an interface for creating objects, but let subclasses to decide which class to instantiate

3. Refers to the newly created object through a common interface

4. Structure

1. Participant:

   1. Factory provides a client with a common interface. The factorymethod returns a product, which may be used by factory's method, such as doSomething()

   2. ConcreteFactory overrides the factorymethod in factory to create a concrete Product

   3. Produt defines the interface for objects the factorymethod creates

   4. ConcreteProduct: implements the Product interface

   5. Collaboration

      1. a Client requires Factory doSomething

      2. a ConcreteFactory call its factorymethod to create a ConcreteProduct

      3. the ConcreteFactory do something with the concrete product

   6. Consequence:

• • 1. Advantage:

    2. The factorymethod separate the time to create an object and what to create, so the process to use the product can be reused and not changed by the change of product

    3. Disadvantage:

    4. The factorymethod pattern only provides clients a type of product at a time

Ref: http://www.oodesign.com/factory-method-pattern.html