- Aka: Kit.
- Intent: Provide an interface for creating families of related or dependent objects without specifying their concrete classes
Structure §
Image from: Gamma, Helm, Johnson, and Vissides
Applicability §
- A system should be independent of how its products are created, composed, and represented.
- A system should be configured with one of multiple families of products.
- A family of related product objects is designed to be used together and you need to enforce this without constraint.
- You want to provide a class library of products and you want to reveal their interfaces, not their implementations
Consequences §
- It isolates concrete classes.
- It makes exchanging product families easy
- It promotes consistency among products.
- Supporting new kinds of products is difficult.
Implementation §
Implement a Factory as a singleton. §
Creating the product: §
- Define a factory method for each product.
- Implement using the Prototype patterns if many product families are possible.
Defining Extensible Factories: §
- Define a different operation for each kind of product; this requires changing the Abstract Factory.
- Add a parameter to operations that create objects to specify the kind of object created; more flexible, less safe.