Creational | Factory method design pattern

Creational design pattern.


Principle:
"Separate out the codes which are subject to change and not subject to change"

Manager (talks to) -> Factory (creates) --> Objects


Factory method:

That method, which has the logic of creating the object based on some certain criteria, are calls "factory method"


Advantage:
1. Avoid code duplication by reusing the creational logic.
2. Separate changing logic vs non changing logic
3. OCP, principle applied 


Abstract factory method


MembershipManager (has some concrete policy as general and abstract method for subclass to implement based on region) 

LondonMemborshipManager , NYMembershipManager