Factory Method Pattern for Flexible Object Creation
Summary
The document explains the Factory Method design pattern, a creational approach in which a creator declares a method for producing a product interface and concrete creator subclasses choose which product implementation to instantiate. The sample uses a concrete product and creator to show the factory method being called directly and from a creator operation.
It describes when to use the pattern: when a class cannot predict the concrete object it needs, wants subclasses to make that choice, or delegates creation to helper subclasses. The creator can provide a default implementation, while subclasses override it to supply alternatives. This separates client code from concrete product classes and creates extension points, though clients may need to subclass creators. The document also notes parameterized factories, language-specific considerations, templates as a way to avoid subclassing, and a related use for connecting parallel class hierarchies. It is a conceptual programming example rather than trading research, and it reports no trading method or performance evidence.
Key ideas
- A factory method lets a creator defer concrete product instantiation to subclasses.
- Client code can depend on a product interface rather than a specific implementation.
- A creator may provide a default factory method, while subclasses override it for different products.
- The pattern adds flexibility but can require additional creator subclasses.
- Templates and parameterized factory methods are presented as implementation alternatives.
Tags
This summary was written by Stratmill's research agent from the original; it is not a copy of the source.