Factory

• defines an interface for creating an object, but allows subclasses to alter the type of objects that will be created

pros

• Single Responsibility Principle (SRP)
  • object creation code is isolated in one place, making the code easier to support
• Open/Closed Principle (OCP)
  • you can introduce new variants of products without breaking existing client code

cons

• code may become more complicated than it should be since a lot of new subclasses are introduced along with the pattern

usages

• when you don’t know beforehand the exact types and dependencies of the objects your code should work with
• when you want to provide users of your library or framework with a way to extend its internal components

relations

• Iterator - Factory
  • to let collection subclasses return different types of iterators that are compatible with the collections
• Template - Factory
  • Factory is a specialization of Template
  • at the same time, a Factory may serve as a step in a large Template

Abstract Factory

• provides an interface for creating families of related or dependent objects without specifying their concrete classes

pros

• Single Responsibility Principle (SRP)
  • object creation code is isolated in one place, making the code easier to support
• Open/Closed Principle (OCP)
  • you can introduce new variants of products without breaking existing client code

cons