The Factory Method Pattern allows subclasses to determine which object to create by overriding a factory method, providing flexibility in object creation. It defines an interface for creating objects but lets subclasses decide which class to instantiate. This pattern is useful when the class that creates the object is different than the class that knows which object is required or when subclasses need to specify the objects that will be created. The document provides an example of applying the Factory Method Pattern to a banking account management system to create different account objects based on configuration parameters while avoiding violations of the Open/Closed Principle.

1. Factory Method Pattern
Shahriar Iqbal Chowdhury & Monjurul Habib
Code Name: Remington
http://www.facebook.com/groups/netter/

2. Why We need Factory? Caveman Example

4. The Solution

5. A specialist for the job

6. Factory Pattern Method Basics
• Creational Pattern
• Which object to create
• It lets a class defer instantiation to subclasses.
• Absolutely all constructors should be private or protected
• Also known as Virtual Constructor.

7. When to consider?
• When we have a class that implements an interface but not sure
which object, which concrete instantiation / implementation need to
return.
• When we need to separate instantiation from the representation.
• When we have lots of select and switch statements for deciding
which concrete class to create and return.

8. Factory Says
Define an interface for creating an object, but let subclasses decide which class to instantiate

9. Problem without Factory Method Pattern

10. Solution Applying Factory Method Pattern

11. Banking Account Management System

12. Object is created based on
configuration parameters

13. Violation of OCP
(Open Close
Principle of SOLID)

14. we will need to create a property that indicates type in each account class