[Head First Design Patterns] Factory Pattern

12 Apr 2022

Factory Pattern

• to solve the problem about complexity by using conditional if/else method
• to encapsulate the object creation to another component, to make it easy for changing, understanding and modifying
• to follow the single responsibilty principle - every object/function only handles one thing and always only has one reason to change

Def

• Factory pattern defines an interface for creating an object, but lets subclass decides which class to initiate. It lets a class defer instantiation to subclass
• Decoupling Products class and Creators class
• 3 types of factory patterns 1) Simple Factory 2) Factory Method 3) Abstract Factory

Design principles

• Dependency Inversion Principle: depend upon abstraction, do not depend upon concrete classes (high level modules should not depend on low level modules; both should depend on abstractions)

Implementation

• The idea is just letting to other classes implement object creation against on provided parameters
• source code