Editing Factory method pattern (section)

==Definition==
According to ''[[Design Patterns|Design Patterns: Elements of Reusable Object-Oriented Software]]'': "Define an interface for creating an object, but let subclasses decide which class to instantiate. Factory method lets a class defer instantiation to subclasses."<ref name="gof">{{cite book |last1=Gamma |first1=Erich |author1-link=Erich Gamma |title=Design Patterns: Elements of Reusable Object-Oriented Software |title-link=Design Patterns |last2=Helm |first2=Richard |author2-link=Richard Helm |last3=Johnson |first3=Ralph |author3-link=Ralph Johnson (computer scientist) |last4=Vlissides |first4=John |author4-link=John Vlissides |publisher=Addison-Wesley |year=1995 |isbn=0-201-63361-2}}</ref>

Creating an object often requires complex processes not appropriate to include within a composing object. The object's creation may lead to a significant duplication of code, may require information inaccessible to the composing object, may not provide a sufficient level of abstraction or may otherwise not be included in the composing object's [[concern (computer science)|concerns]]. The factory method design pattern handles these problems by defining a separate [[method (computer science)|method]] for creating the objects, which subclasses can then override to specify the [[Subtyping|derived type]] of product that will be created.

The factory method pattern relies on inheritance, as object creation is delegated to subclasses that implement the factory method to create objects.<ref>{{cite book |last1=Freeman |first1=Eric |url=http://shop.oreilly.com/product/9780596007126.do |title=Head First Design Patterns: A Brain-Friendly Guide |last2=Robson |first2=Elisabeth |last3=Sierra |first3=Kathy |last4=Bates |first4=Bert |publisher=O'Reilly Media |year=2004 |isbn=978-0-596-00712-6 |editor-last1=Hendrickson |editor-first1=Mike |edition=1st |volume=1 |page=162 |format=paperback |access-date=2012-09-12 |editor-last2=Loukides |editor-first2=Mike}}</ref>
The pattern can also rely on the implementation of an [[Interface (object-oriented programming)|interface]].